ampicillin

Penicillinase-Sensitive Penicillin Antibiotics

Oral Administration

All dosage forms: Take on an empty stomach (i.e., at least 30 minutes prior to or 2 hours after a meal).

Oral Liquid Formulations

Shake well prior to each use.
 
Reconstitution
Review the manufacturer reconstitution instructions for the particular product and package size.
Add water in 2 portions and shake well after each addition.
Storage: Store reconstituted suspension in refrigerator; discard after 14 days.

Injectable Administration

Ampicillin sodium may be administered intramuscularly (IM), by slow intravenous (IV) push, or by IV infusion.
Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit.
Do not administer ampicillin at the same time or mix in the same container as aminoglycosides. Beta-lactam antibiotics such as ampicillin may inactivate aminoglycoside antibiotics when combined.

Intravenous Administration

IV Push
Reconstitution
Bacteriostatic Water for Injection should not be used for preparation of neonatal doses.
125 mg, 250 mg, and 500 mg vials: Reconstitute the 125 mg, 250 mg, and 500 mg vials with 5 mL of Sterile Water for Injection or Bacteriostatic Water for Injection for a resultant concentration of 25 mg/mL, 50 mg/mL, and 100 mg/mL, respectively.
1 and 2 g vials: Reconstitute the 1 g and 2 g vials with 7.4 or 14.8 mL of Sterile Water for Injection or Bacteriostatic Water for Injection, respectively, for a resultant concentration of 125 mg/mL.
Swirl vial and ensure that all drug is completely dissolved into solution.
Withdraw the appropriate dose from the vial and administer within 1 hour of reconstitution.
IV Push Administration
125 mg, 250 mg, and 500 mg doses: Administer as slow IV push over at least 3 to 5 minutes.
1 and 2 g doses: Administer as slow IV push over at least 10 to 15 minutes.
Do not administer faster than recommended as more rapid administration may result in seizures.
 
Intermittent IV Infusion
Reconstitution/Dilution
125 mg, 250 mg, and 500 mg vials: Reconstitute the 125 mg, 250 mg, and 500 mg vials with 5 mL of Sterile Water for Injection or Bacteriostatic Water for Injection for a resultant concentration of 25 mg/mL, 50 mg/mL, and 100 mg/mL, respectively.
1 and 2 g vials: Reconstitute the 1 g and 2 g vials with 7.4 or 14.8 mL of Sterile Water for Injection or Bacteriostatic Water for Injection, respectively, for a resultant concentration of 125 mg/mL.
Pharmacy Bulk Vial: The 10 g vial is designed for use in preparing multiple IV admixtures. Add 94 mL Sterile Water for Injection. The resulting solution will contain 100 mg/mL ampicillin and is stable up to 1 hour at room temperature.
Once vials are prepared, withdraw the appropriate dose and further dilute with a compatible fluid (e.g., 0.9% NaCl Injection) to a usual concentration of 10 to 30 mg/mL.
Stability is dependent on the diluent chosen, the final concentration, and the storage conditions and may range from 1 hour to 72 hours. Consult ampicillin full prescribing information (i.e., package insert) for detailed stability information.
 
Intermittent IV Infusion Administration
Infuse appropriate dose IV over 15 to 30 minutes.

Intramuscular Administration

Reconstitution
Reconstitute the 125 mg vial with 1.2 mL of Sterile Water for Injection or Bacteriostatic Water for Injection for a resultant concentration of 125 mg/mL. Reconstitute 250 mg, 500 mg, 1 g, and 2 g vials with 1 mL, 1.8 mL, 3.5 mL, and 6.8 mL of Sterile Water for Injection or Bacteriostatic Water for Injection, respectively, for a resultant concentration of 250 mg/mL.
Administer within 1 hour of preparation.
 
Intramuscular (IM) Injection
Withdraw appropriate dose and inject deeply into a large muscle mass (e.g., anterolateral thigh or deltoid [children and adolescents only]).
In general, IM administration of antibiotics in very low birth weight premature neonates is not practical due to small muscle mass, and absorption is unreliable due to hemodynamic instability that is relatively common in this population.

Severe

serum sickness / Delayed / 0-5.0
erythema multiforme / Delayed / 0-5.0
exfoliative dermatitis / Delayed / 0-5.0
enterocolitis / Delayed / 2.0-5.0
anaphylactoid reactions / Rapid / Incidence not known
angioedema / Rapid / Incidence not known
anaphylactic shock / Rapid / Incidence not known
acute generalized exanthematous pustulosis (AGEP) / Delayed / Incidence not known
thrombotic thrombocytopenic purpura (TTP) / Delayed / Incidence not known
agranulocytosis / Delayed / Incidence not known
odynophagia / Delayed / Incidence not known
seizures / Delayed / Incidence not known
C. difficile-associated diarrhea / Delayed / Incidence not known

Moderate

stomatitis / Delayed / 2.0-5.0
glossitis / Early / 2.0-5.0
dysphagia / Delayed / 2.0-5.0
leukopenia / Delayed / Incidence not known
thrombocytopenia / Delayed / Incidence not known
platelet dysfunction / Delayed / Incidence not known
anemia / Delayed / Incidence not known
prolonged bleeding time / Delayed / Incidence not known
eosinophilia / Delayed / Incidence not known
esophagitis / Delayed / Incidence not known
elevated hepatic enzymes / Delayed / Incidence not known
pseudomembranous colitis / Delayed / Incidence not known
superinfection / Delayed / Incidence not known

Mild

rash / Early / 0-5.0
maculopapular rash / Early / 0-5.0
urticaria / Rapid / 0-5.0
pruritus / Rapid / 0-5.0
nausea / Early / 2.0-5.0
tongue discoloration / Delayed / 2.0-5.0
vomiting / Early / 2.0-5.0
diarrhea / Early / 2.0-5.0
fever / Early / Incidence not known
Jarisch-Herxheimer reaction / Early / Incidence not known

Principen

Rx

Aminopenicillin similar to amoxicillin; not stable to beta-lactamases of either gram-positive or gram-negative bacteria; used commonly for obstetric infections, otitis media, sinusitis and other infections due to susceptible organisms; oral ampicillin exhibits lower bioavailability and higher incidence of GI effects than amoxicillin.

For the treatment of severe infections, including bacteremia. Intravenous or Intramuscular dosage Adults

150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours. While the product labeling does not recommend a maximum dose, guidelines note 12 g/day IV for serious infections.

Infants, Children, and Adolescents

50 to 200 mg/kg/day (Max: 8 g/day) IV or IM divided every 6 hours. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Neonates older than 34 weeks gestation

50 mg/kg/dose IV or IM every 8 hours.

Neonates 34 weeks gestation and younger and older than 7 days

75 mg/kg/dose IV or IM every 12 hours.

Neonates 34 weeks gestation and younger and 0 to 7 days

50 mg/kg/dose IV or IM every 12 hours.

For the treatment of infective endocarditis. Intravenous or Intramuscular dosage Adults

2 g IV every 4 hours is recommended by guidelines. Ampicillin in combination with gentamicin is recommended as an alternative to penicillin in the setting of shortage for endocarditis due to highly penicillin-susceptible or resistant Viridans group streptococci and S. gallolyticus (bovis) infections; treat for 4 weeks for native valve endocarditis (NVE) and for 6 weeks for prosthetic valve endocarditis (PVE). Ampicillin in combination with gentamicin (or streptomycin) or ceftriaxone is preferred for penicillin-susceptible enterococcal endocarditis; treat for 4 to 6 weeks for NVE and for 6 weeks for PVE or if used with ceftriaxone. Combination therapy with daptomycin may be considered in patients with persistent penicillin-resistant enterococcal bacteremia or strains with high daptomycin MICs; treat for at least 6 weeks. Pending susceptibility data, ampicillin may be an option for endocarditis due to HACEK microorganisms; treat for 4 weeks for NVE and for 6 weeks for PVE. The FDA-approved labeling recommends 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Children and Adolescents

200 to 400 mg/kg/day IV divided every 4 to 6 hours (Max: 12 g/day) is recommended by guidelines. Ampicillin is recommended as an alternative to penicillin in the setting of penicillin unavailability for streptococcal endocarditis; treat for 4 weeks for native valve endocarditis (NVE) and for 6 weeks for prosthetic valve endocarditis (PVE). Use in combination with gentamicin for streptococcal PVE; duration of concurrent gentamicin (2 or 6 weeks) depends on susceptibility and/or organism. Ampicillin in combination with gentamicin is recommended as preferred therapy for enterococcal infections; treat for 4 to 6 weeks, with a longer course for PVE. Alternately, may use in combination with ceftriaxone in aminoglycoside-resistant enterococcal infection or aminoglycoside-intolerant patient. Ampicillin plus an aminoglycoside for 4 weeks is recommended as an alternate therapy for endocarditis due to HACEK microorganisms. The FDA-approved labeling recommends 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Infants

300 to 400 mg/kg/day IV or IM divided every 4 hours is recommended by the American Academy of Pediatrics (AAP). The FDA-approved labeling recommends 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Neonates older than 34 weeks gestation

50 mg/kg/dose IV or IM every 8 hours.

Neonates 34 weeks gestation and younger and older than 7 days

75 mg/kg/dose IV or IM every 12 hours.

Neonates 34 weeks gestation and younger and 0 to 7 days

50 mg/kg/dose IV or IM every 12 hours.

For the treatment of upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs), including community-acquired pneumonia (CAP). For the treatment of nonspecific respiratory tract infections (RTIs). Oral dosage Adults

250 mg PO 4 times daily.

Infants, Children, and Adolescents

50 to 100 mg/kg/day PO in 4 divided doses (Max: 2 g/day) is recommended by the American Academy of Pediatrics (AAP).[63245] The FDA-approved dose is 50 mg/kg/day PO in 3 to 4 divided doses (Max: 1 g/day).[51868] Compared to amoxicillin, oral ampicillin has a lower bioavailability and is more likely to cause adverse GI effects.[51854]

Intravenous or Intramuscular dosage Adults weighing 40 kg or more

250 to 500 mg IV or IM every 6 hours.

Adults weighing less than 40 kg

25 to 50 mg/kg/day IV or IM divided every 6 to 8 hours.

Infants, Children, and Adolescents

50 to 200 mg/kg/day IV or IM divided every 6 hours (Max: 8 g/day) is recommended by the American Academy of Pediatrics (AAP).[63245] The FDA-approved dose is 25 to 50 mg/kg/day IV or IM divided every 6 to 8 hours (Max: 2 g/day).[43344]

Neonates older than 34 weeks gestation†

50 mg/kg/dose IV or IM every 8 hours.

Neonates 34 weeks gestation and younger and older than 7 days†

75 mg/kg/dose IV or IM every 12 hours.

Neonates 34 weeks gestation and younger and 0 to 7 days†

50 mg/kg/dose IV or IM every 12 hours.

For the treatment of community-acquired pneumonia (CAP). Intravenous or Intramuscular dosage Infants 4 to 11 months, Children, and Adolescents

150 to 200 mg/kg/day IV or IM in divided doses every 6 hours (Max: 12 g/day) for 10 days as empiric treatment and 300 to 400 mg/kg/day IV or IM divided every 6 hours for 10 days as an alternative to ceftriaxone for resistant strains of S. pneumoniae.

For the treatment of skin and skin structure infections (e.g., cellulitis). Intravenous or Intramuscular dosage Adults weighing 40 kg or more

250 to 500 mg IV or IM every 6 hours.

Adults weighing less than 40 kg

25 to 50 mg/kg/day IV or IM divided every 6 to 8 hours.

Infants, Children, and Adolescents

50 to 200 mg/kg/day (Max: 8 g/day) IV or IM divided every 6 hours. The FDA-approved dosage is 25 to 50 mg/kg/day IV or IM divided every 6 to 8 hours (Max: 2 g/day).

Neonates older than 34 weeks gestation†

50 mg/kg/dose IV or IM every 8 hours.

Neonates 34 weeks gestation and younger and older than 7 days†

75 mg/kg/dose IV or IM every 12 hours.

Neonates 34 weeks gestation and younger and 0 to 7 days†

50 mg/kg/dose IV or IM every 12 hours.

For the treatment of urinary tract infection (UTI), including pyelonephritis. For the treatment of nonspecific UTI. Oral dosage Adults

500 mg PO 4 times daily.

Infants, Children, and Adolescents

100 mg/kg/day (Max: 2 g/day) PO in 4 divided doses.

Intravenous or Intramuscular dosage Adults weighing 40 kg or more

500 mg IV or IM every 6 hours.

Adults weighing less than 40 kg

50 mg/kg/day IV or IM divided every 6 to 8 hours. Higher doses may be needed for severe infections.

Infants, Children, and Adolescents

50 to 200 mg/kg/day (Max: 8 g/day) IV or IM divided every 6 hours. The FDA-approved dosage is 50 mg/kg/day (Max: 2 g/day) IV or IM divided every 6 to 8 hours.

Neonates older than 34 weeks gestation†

50 mg/kg/dose IV or IM every 8 hours.

Neonates 34 weeks gestation and younger and older than 7 days†

75 mg/kg/dose IV or IM every 12 hours.

Neonates 34 weeks gestation and younger and 0 to 7 days†

50 mg/kg/dose IV or IM every 12 hours.

For the treatment of pyelonephritis. Intravenous dosage Adults

500 mg IV every 6 hours with an aminoglycoside for 7 to 14 days. Higher doses may be needed for severe infections.

For the treatment of gastrointestinal infections (e.g., enterocolitis, gastroenteritis), including dysentery/shigellosis, salmonellosis, and typhoid fever. For the treatment of general gastrointestinal infections, including dysentery/shigellosis and salmonellosis. Oral dosage Adults

500 mg PO every 6 hours.

Infants, Children, and Adolescents

100 mg/kg/day (Max: 2 g/day) PO divided every 6 hours.

Intravenous or Intramuscular dosage Adults weighing 40 kg or more

500 mg IV or IM every 6 hours. Higher doses may be needed for severe infections.

Adults weighing less than 40 kg

50 mg/kg/day IV or IM divided every 6 to 8 hours. Higher doses may be needed for severe infections.

Infants, Children, and Adolescents

50 to 200 mg/kg/day (Max: 8 g/day) IV or IM divided every 6 hours. The FDA-approved dosage is 50 mg/kg/day (Max: 2 g/day) IV or IM divided every 6 to 8 hours.

Neonates older than 34 weeks gestation†

50 mg/kg/dose IV or IM every 8 hours.

Neonates 34 weeks gestation and younger and older than 7 days†

75 mg/kg/dose IV or IM every 12 hours.

Neonates 34 weeks gestation and younger and 0 to 7 days†

50 mg/kg/dose IV or IM every 12 hours.

For the treatment of fully sensitive uncomplicated typhoid fever. Oral dosage Adults

50 to 100 mg/kg/day PO divided every 6 to 8 hours for 14 days as an alternative.

Infants, Children, and Adolescents

50 to 100 mg/kg/day PO divided every 6 to 8 hours (Max: 500 mg/dose) for 14 days as an alternative.

For the treatment of fully sensitive severe typhoid fever. Intravenous or Intramuscular dosage Adults

100 mg/kg/day IV or IM divided every 6 to 8 hours for 14 days as an alternative. Usual dose: 2 g IV every 6 hours.

Infants, Children, and Adolescents

100 to 200 mg/kg/day IV or IM divided every 6 to 8 hours (Max: 2 g/dose) for 14 days as an alternative.

For the treatment of uncomplicated gonorrhea. Oral dosage Adults

Not recommended by guidelines. The FDA-approved dosage is 3.5 g PO as a single dose in combination with probenecid.

Intravenous dosage Adult Females weighing 40 kg or more

Not recommended by guidelines. The FDA-approved dosage is 500 mg IV or IM every 6 hours.

Adult Females weighing less than 40 kg

Not recommended by guidelines. The FDA-approved dosage is 50 mg/kg/day IV or IM divided every 6 to 8 hours.

Adult Males

Not recommended by guidelines. The FDA-approved dosage is 500 mg IV or IM every 8 to 12 hours for 2 doses.

For the treatment of meningitis and ventriculitis†. For the treatment of Listeria meningitis. Intravenous or Intramuscular dosage Adults

2 g IV every 4 hours for at least 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Infants, Children, and Adolescents

300 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours for at least 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours for at least 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 75 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours for at least 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 50 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

For the treatment of meningococcal meningitis as well as meningitis or ventriculitis† due to H. influenzae. Intravenous or Intramuscular dosage Adults

2 g IV every 4 hours for 7 days. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Infants, Children, and Adolescents

300 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours for 7 days. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours for 7 days. The FDA-approved dosage is 75 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours for 7 days. The FDA-approved dosage is 50 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

For the treatment of pneumococcal meningitis†. Intravenous dosage Adults

2 g IV every 4 hours for 10 to 14 days.

Infants, Children, and Adolescents

300 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours for 10 to 14 days.

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours for 10 to 14 days.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours for 10 to 14 days.

For the treatment of meningitis due to S. agalactiae (group B streptococcal meningitis). Intravenous or Intramuscular dosage Adults

2 g IV every 4 hours for 14 to 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Infants, Children, and Adolescents

300 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours for 14 to 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours for 14 to 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 75 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours for 14 to 21 days; consider the addition of an aminoglycoside. The FDA-approved dosage is 50 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

For the treatment of enterococcal meningitis†. Intravenous dosage Adults

2 g IV every 4 hours in combination with gentamicin for 14 to 21 days.

Infants, Children, and Adolescents

300 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours in combination with gentamicin for 14 to 21 days. 

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours in combination with gentamicin for 14 to 21 days.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours in combination with gentamicin for 14 to 21 days.

For the treatment of meningitis due to aerobic gram-negative rods. Intravenous or Intramuscular dosage Adults

2 g IV every 4 hours for 21 days. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Infants, Children, and Adolescents

300 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours for 21 days. The FDA-approved dosage is 150 to 200 mg/kg/day IV or IM divided every 3 to 4 hours.

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours for 2 weeks beyond the first sterile CSF culture or at least 21 days, whichever is longer. The FDA-approved dosage is 75 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours for 2 weeks beyond the first sterile CSF culture or at least 21 days, whichever is longer. The FDA-approved dosage is 50 mg/kg/dose IV every 12 hours for neonates 34 weeks gestation and younger and 50 mg/kg/dose IV every 8 hours for neonates older than 34 weeks gestation.

For the treatment of leptospirosis†. Oral dosage Adults

500 to 750 mg PO every 6 hours for 7 days as alternative therapy for mild or moderate disease.

Infants, Children, and Adolescents

50 to 100 mg/kg/day (Max: 2 g/day) PO divided every 6 hours for 7 to 10 days as alternative therapy for mild or moderate disease.

For bacterial endocarditis prophylaxis†. Intramuscular or Intravenous dosage Adults

2 g IV or IM as a single dose given 30 to 60 minutes before procedure as an alternative for patients unable to take oral medication. Prophylaxis is recommended for at-risk cardiac patients who are undergoing dental procedures that involve manipulation of gingival tissue, manipulation of the periapical region of teeth, or perforation of the oral mucosa.

Children and Adolescents

50 mg/kg/dose (Max: 2 g/dose) IV or IM as a single dose given 30 to 60 minutes before procedure as an alternative for patients unable to take oral medication. Prophylaxis is recommended for at-risk cardiac patients who are undergoing dental procedures that involve manipulation of gingival tissue, manipulation of the periapical region of teeth, or perforation of the oral mucosa.

For perinatal Group B streptococcal infection prophylaxis†. Intravenous dosage Adults

2 g IV loading dose at the time of labor or rupture of membranes, followed by 1 g IV every 4 hours until delivery as an alternative. Antibiotics administered for at least 4 hours before delivery have been found to be highly effective at preventing the transmission of Group B Streptococcus. Antibiotics given to prolong latency for preterm premature rupture of membranes (PROM) with adequate Group B Streptococcus coverage (specifically ampicillin 2 g IV every 6 hours for 48 hours) are sufficient for prophylaxis if delivery occurs while receiving that antibiotic regimen.

Adolescents

2 g IV loading dose at the time of labor or rupture of membranes, followed by 1 g IV every 4 hours until delivery as an alternative. Antibiotics administered for at least 4 hours before delivery have been found to be highly effective at preventing the transmission of Group B Streptococcus. Antibiotics given to prolong latency for preterm premature rupture of membranes (PROM) with adequate Group B Streptococcus coverage (specifically ampicillin 2 g IV every 6 hours for 48 hours) are sufficient for prophylaxis if delivery occurs while receiving that antibiotic regimen.

For the treatment of intraabdominal infections†, including peritonitis†, appendicitis†, intraabdominal abscess†, neonatal necrotizing enterocolitis†, and peritoneal dialysis-related peritonitis†. For the treatment of complicated community-acquired, healthcare-acquired, or hospital-acquired intraabdominal infections† with adequate source control. Intravenous dosage Adults

1 to 2 g IV every 4 to 6 hours as part of combination therapy for 3 to 7 days. Complicated infections include peritonitis and appendicitis complicated by rupture, and intraabdominal abscess.

Infants, Children, and Adolescents

100 to 200 mg/kg/day (Max: 8 g/day) IV divided every 6 hours as part of combination therapy for 3 to 7 days. Complicated infections include peritonitis and appendicitis complicated by rupture, and intraabdominal abscess.

Neonates older than 34 weeks gestation

50 mg/kg/dose IV every 8 hours as part of combination therapy for 7 to 10 days. Ampicillin is an option for necrotizing enterocolitis.

Neonates 34 weeks gestation and younger and older than 7 days

75 mg/kg/dose IV every 12 hours as part of combination therapy for 7 to 10 days. Ampicillin is an option for necrotizing enterocolitis.

Neonates 34 weeks gestation and younger and 0 to 7 days

50 mg/kg/dose IV every 12 hours as part of combination therapy for 7 to 10 days. Ampicillin is an option for necrotizing enterocolitis.

For the treatment of uncomplicated intraabdominal infections†. Intravenous dosage Adults

1 to 2 g IV every 4 to 6 hours as part of combination therapy. Antibiotics should be discontinued within 24 hours. Uncomplicated infections include acute appendicitis without perforation, abscess, or local peritonitis; traumatic bowel perforations repaired within 12 hours; acute cholecystitis without perforation; and ischemic, non-perforated bowel.

Infants, Children, and Adolescents

100 to 200 mg/kg/day (Max: 8 g/day) IV divided every 6 hours part of combination therapy. Antibiotics should be discontinued within 24 hours. Uncomplicated infections include acute appendicitis without perforation, abscess, or local peritonitis; traumatic bowel perforations repaired within 12 hours; acute cholecystitis without perforation; and ischemic, non-perforated bowel.

For the treatment of peritoneal dialysis-related peritonitis†. Continuous Intraperitoneal dosage† Adults

125 mg/L in each dialysate exchange. Treat for 14 to 21 days.

Infants, Children, and Adolescents

125 mg/L in each dialysate exchange. Treat for 14 to 21 days.

For surgical infection prophylaxis† in patients undergoing liver transplantation. Intravenous or Intramuscular dosage Adults

2 g IV or IM as a single dose within 60 minutes prior to the surgical incision, in combination with cefotaxime. Intraoperative redosing 2 hours from the first preoperative dose and a duration of prophylaxis less than 24 hours are recommended by clinical practice guidelines.

Infants, Children, and Adolescents

50 mg/kg IV or IM as a single dose (Max: 2 g/dose) within 60 minutes prior to the surgical incision, in combination with cefotaxime. Intraoperative redosing 2 hours from the first preoperative dose and a duration of prophylaxis less than 24 hours are recommended by clinical practice guidelines.

For the treatment of systemic anthrax† infection. Intravenous dosage Adults

3 g IV every 6 hours. Ampicillin, in combination with a fluoroquinolone and protein synthesis inhibitor (i.e., linezolid, clindamycin), is an alternative therapy for the treatment of systemic anthrax due to penicillin-susceptible strains in which meningitis cannot be excluded. Ampicillin, in combination with a protein synthesis inhibitor (i.e., clindamycin, linezolid), is an alternative therapy in systemic anthrax infection due to penicillin-susceptible strains without CNS involvement. For systemic infection in which meningitis cannot be excluded, treatment should continue for at least 2 to 3 weeks or until clinical criteria for improvement are met. For systemic infection without CNS involvement, treatment should continue for at least 14 days or until clinical criteria for improvement are met. Prophylaxis to complete an antimicrobial course of up to 60 days will be required in both cases.

Infants, Children, and Adolescents

50 mg/kg/dose IV every 6 hours (Max: 3 g/dose) for systemic infection without CNS involvement and 100 mg/kg/dose IV every 6 hours (Max: 3 g/dose) for systemic infection with documented/suspected CNS involvement. For systemic infection in which meningitis can be excluded, IV treatment should continue for at least 14 days or until clinical criteria for improvement are met. For systemic infection in which meningitis cannot be excluded, IV treatment should continue for at least 2 to 3 weeks or until clinical criteria for improvement are met. Prophylaxis to complete an antimicrobial course of up to 60 days will be required in both cases. Ampicillin, in combination with appropriate antimicrobial therapy, is an alternative therapy for the treatment of systemic anthrax due to penicillin-susceptible strains. For systemic infection without CNS involvement, dual combination IV therapy with ampicillin and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended. For documented or suspected CNS infection, triple IV therapy with ampicillin, a fluoroquinolone, and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended.

Premature Neonates 34 to 37 weeks gestation and Term Neonates older than 7 days

50 mg/kg/dose IV every 6 hours. For systemic infection in which meningitis can be excluded, IV treatment should continue for at least 14 days or until clinical criteria for improvement are met. For systemic infection in which meningitis cannot be excluded, IV treatment should continue for at least 2 to 3 weeks or until clinical criteria for improvement are met. Prophylaxis to complete an antimicrobial course of up to 60 days will be required in both cases. Ampicillin, in combination with appropriate antimicrobial therapy, is an alternative therapy for the treatment of systemic anthrax due to penicillin-susceptible strains. For systemic infection without CNS involvement, dual combination IV therapy with ampicillin and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended. For documented or suspected CNS infection, triple IV therapy with ampicillin, a fluoroquinolone, and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended.

Premature Neonates 34 to 37 weeks gestation and Term Neonates 0 to 7 days

50 mg/kg/dose IV every 8 hours. For systemic infection in which meningitis can be excluded, IV treatment should continue for at least 14 days or until clinical criteria for improvement are met. For systemic infection in which meningitis cannot be excluded, IV treatment should continue for at least 2 to 3 weeks or until clinical criteria for improvement are met. Prophylaxis to complete an antimicrobial course of up to 60 days will be required in both cases. Ampicillin, in combination with appropriate antimicrobial therapy, is an alternative therapy for the treatment of systemic anthrax due to penicillin-susceptible strains. For systemic infection without CNS involvement, dual combination IV therapy with ampicillin and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended. For documented or suspected CNS infection, triple IV therapy with ampicillin, a fluoroquinolone, and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended.

Premature Neonates 32 to 34 weeks gestation and older than 7 days

50 mg/kg/dose IV every 8 hours. For systemic infection in which meningitis can be excluded, IV treatment should continue for at least 14 days or until clinical criteria for improvement are met. For systemic infection in which meningitis cannot be excluded, IV treatment should continue for at least 2 to 3 weeks or until clinical criteria for improvement are met. Prophylaxis to complete an antimicrobial course of up to 60 days will be required in both cases. Ampicillin, in combination with appropriate antimicrobial therapy, is an alternative therapy for the treatment of systemic anthrax due to penicillin-susceptible strains. For systemic infection without CNS involvement, dual combination IV therapy with ampicillin and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended. For documented or suspected CNS infection, triple IV therapy with ampicillin, a fluoroquinolone, and a protein synthesis inhibitor (i.e., linezolid, clindamycin) is recommended.

Premature Neonates 32 to 34 weeks gestation and 0 to 7 days

50 mg/kg/dose IV every 12 hours. For systemic infection in which meningitis can be excluded, IV treatment should continue for at least 14 days or until clinical criteria for improvement are met. For systemic infection in which meningitis cannot be excluded, IV treatment should continue for at least 2 to 3 weeks or until clinical criteria for improvement are met. Prophylaxis to complete an antimicrobial course of up to 60 days will be required in both cases. Ampicillin, in combination with appropriate antimicrobial therapy, is an alternative therapy for the treatment of systemic anthrax due to penicillin-susceptible strains. For systemic infection without CNS involvement, dual combination IV therapy with ampicillin and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended. For documented or suspected CNS infection, triple IV therapy with ampicillin, a fluoroquinolone, and a protein synthesis inhibitor (i.e., clindamycin, linezolid) is recommended.

For the prolongation of latency and reduction of maternal and neonatal infections and neonatal morbidity in persons with preterm premature rupture of membranes† (PROM). Intravenous dosage Adults

2 g IV every 6 hours for 48 hours in combination with IV erythromycin for 48 hours or a single oral dose of azithromycin followed by oral step-down therapy for 5 days. A 7-day course of therapy with broad-spectrum antibiotics is recommended for pregnant persons with preterm PROM who are less than 34 0/7 weeks gestation. Persons with preterm PROM who are candidates for Group B streptococcal (GBS) intrapartum prophylaxis should receive GBS prophylaxis to prevent vertical transmission regardless of earlier treatments.

Adolescents

2 g IV every 6 hours for 48 hours in combination with IV erythromycin for 48 hours or a single oral dose of azithromycin followed by oral step-down therapy for 5 days. A 7-day course of therapy with broad-spectrum antibiotics is recommended for pregnant persons with preterm PROM who are less than 34 0/7 weeks gestation. Persons with preterm PROM who are candidates for Group B streptococcal (GBS) intrapartum prophylaxis should receive GBS prophylaxis to prevent vertical transmission regardless of earlier treatments.

For chronic typhoid carriage eradication†. Oral dosage Adults

100 mg/kg/day PO divided every 6 to 8 hours plus probenecid for 4 to 6 weeks.

Infants, Children, and Adolescents

100 mg/kg/day PO divided every 6 to 8 hours plus probenecid for 4 to 6 weeks.

For the treatment of chorioamnionitis† or intraamniotic infection†. Intravenous dosage Adults

2 g IV every 6 hours during the intrapartum period as part of combination therapy. Give 1 additional dose after cesarean delivery; an additional dose is generally not needed after vaginal delivery. Other risk factors such as bacteremia or persistent postpartum fever may require additional therapy.

Adolescents

2 g IV every 6 hours during the intrapartum period as part of combination therapy. Give 1 additional dose after cesarean delivery; an additional dose is generally not needed after vaginal delivery. Other risk factors such as bacteremia or persistent postpartum fever may require additional therapy.

For the treatment of postpartum endometritis†. Intravenous dosage Adults

2 g IV once, followed by 1 g IV every 4 hours in combination with gentamicin and metronidazole. Continue treatment until clinical improvement and afebrile for 24 to 48 hours.

For the treatment of listeriosis†.
NOTE: For CNS disease, see meningitis indication.
For the treatment of invasive listeriosis† with bacteremia. Intravenous dosage Adults

2 g IV every 4 to 8 hours for 14 days; consider the addition of gentamicin.

Infants, Children, and Adolescents

100 to 400 mg/kg/day (Max: 12 g/day) IV divided every 4 to 6 hours for 14 days; consider the addition of gentamicin.

Neonates older than 7 days

75 mg/kg/dose IV every 6 hours for 14 days; consider the addition of gentamicin.

Neonates 0 to 7 days

100 mg/kg/dose IV every 8 hours for 14 days; consider the addition of gentamicin.

For the treatment of gastroenteritis due L. monocytogenes† in persons at risk for invasive disease. Oral dosage Adults

500 mg PO every 6 hours for 3 to 7 days.

Infants, Children, and Adolescents

100 mg/kg/day (Max: 2 g/day) PO divided every 6 hours for 3 to 7 days.

†Indicates off-label use

Hepatic Impairment

No dosage adjustment is needed.

Renal Impairment

Adults:
CrCl more than 50 mL/minute: No dosage adjustment needed.
CrCl 10 to 50 mL/minute: Extend dosing interval to every 6 to 12 hours.
CrCl less than 10 mL/minute: Extend dosing interval to every 12 to 24 hours.
 
Pediatrics:
GFR 30 mL/minute/1.73 m2 or more: No dosage adjustment needed.
GFR 10 to 29 mL/minute/1.73 m2: Extend dosing interval to every 8 to 12 hours.
GFR less than 10 mL/minute/1.73 m2: Extend dosing interval to every 12 hours.
 
Intermittent hemodialysis
Ampicillin is significantly removed during a standard hemodialysis session; give recommended dose after dialysis. For pediatric patients, give the recommended dose every 12 hours after dialysis.
 
Peritoneal dialysis
Adults: 250 mg every 12 hours.
Pediatrics: Extend dosing interval to every 12 hours.
 
Continuous renal replacement therapy (CRRT)
Adults: Give recommended dose every 6 to 12 hours.
Pediatrics: Give recommended dose every 6 hours.

Acetaminophen; Aspirin, ASA; Caffeine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Acetaminophen; Aspirin: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Acetaminophen; Aspirin; Diphenhydramine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Allopurinol: (Minor) Use of ampicillin with allopurinol can increase the incidence of drug-related skin rash.
Amoxicillin; Clarithromycin; Omeprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Aspirin, ASA: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Butalbital; Caffeine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Caffeine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Caffeine; Orphenadrine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Carisoprodol: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Carisoprodol; Codeine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Dipyridamole: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Omeprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption. (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Aspirin, ASA; Oxycodone: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Atenolol: (Major) Ampicillin has been reported to reduce the bioavailability of single-dose atenolol, and to increase the tachycardic response to exercise compared to atenolol monotherapy. Monitor clinical response, and adjust atenolol dosage if needed to attain therapeutic goals.
Atenolol; Chlorthalidone: (Major) Ampicillin has been reported to reduce the bioavailability of single-dose atenolol, and to increase the tachycardic response to exercise compared to atenolol monotherapy. Monitor clinical response, and adjust atenolol dosage if needed to attain therapeutic goals.
Butalbital; Aspirin; Caffeine; Codeine: (Minor) Due to the high protein binding of aspirin, it could displace or be displaced from binding sites by other highly protein-bound drugs, such as penicillins. Also, aspirin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. Overall, this combination should be used with caution and patients monitored for increased side effects.
Caffeine; Sodium Benzoate: (Moderate) Antibiotics that undergo tubular secretion such as penicillins may compete with phenylacetlyglutamine and hippuric acid for active tubular secretion. The overall usefulness of sodium benzoate; sodium phenylacetate is due to the excretion of its metabolites. An increase in metabolite concentrations could contribute to failed treatment and worsening of the patient's clinical status. This combination should be used with caution.
Carbidopa; Levodopa; Entacapone: (Moderate) As entacapone is primarily excreted in the bile, caution should be exercised when drugs known to interfere with biliary excretion, glucuronidation, and intestinal beta-glucuronidation, such as ampicillin, are given concurrently with entacapone.
Chloroquine: (Moderate) Administer oral ampicillin 2 hours before or 2 hours after chloroquine. In a study of healthy volunteers, chloroquine significantly reduced the bioavailability of ampicillin. The reduction of ampicillin bioavailability could be attributed to slower gastric emptying and enhancement of gut motility produced by chloroquine.
Choline Salicylate; Magnesium Salicylate: (Minor) Due to high protein binding, salicylates could be displaced from binding sites, or could displace other highly protein-bound drugs such as penicillins, and sulfonamides. An enhanced effect of the displaced drug may occur.
Desogestrel; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Dexlansoprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Dichlorphenamide: (Moderate) Use dichlorphenamide and ampicillin together with caution. Dichlorphenamide increases potassium excretion and can cause hypokalemia and should be used cautiously with other drugs that may cause hypokalemia including ampicillin. Measure potassium concentrations at baseline and periodically during dichlorphenamide treatment. If hypokalemia occurs or persists, consider reducing the dose or discontinuing dichlorphenamide therapy.
Dienogest; Estradiol valerate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Digoxin: (Minor) Displacement of penicillins from plasma protein binding sites by highly protein bound drugs like digoxin will elevate the level of free penicillin in the serum. The clinical significance of this interaction is unclear. It is recommended to monitor these patients for increased adverse effects.
Drospirenone: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Drospirenone; Estetrol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Drospirenone; Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Drospirenone; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Elagolix; Estradiol; Norethindrone acetate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Entacapone: (Moderate) As entacapone is primarily excreted in the bile, caution should be exercised when drugs known to interfere with biliary excretion, glucuronidation, and intestinal beta-glucuronidation, such as ampicillin, are given concurrently with entacapone.
Esomeprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Estradiol; Levonorgestrel: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Estradiol; Norethindrone: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Estradiol; Norgestimate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Ethacrynic Acid: (Minor) Ethacrynic acid may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. This combination should be used with caution and patients monitored for increased side effects.
Ethinyl Estradiol; Norelgestromin: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Ethinyl Estradiol; Norethindrone Acetate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Ethinyl Estradiol; Norgestrel: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Ethynodiol Diacetate; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Etonogestrel; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Furosemide: (Minor) Furosemide may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. This combination should be used with caution and patients monitored for increased side effects.
Hydroxychloroquine: (Moderate) Administer oral ampicillin 2 hours before or 2 hours after hydroxychloroquine. Ampicillin bioavailability may be decreased with coadministration of hydroxychloroquine as a significant reduction in ampicillin bioavailability was observed with the structurally similar chloroquine in a study of healthy volunteers. The reduction of ampicillin bioavailability could be attributed to slower gastric emptying and enhancement of gut motility produced by chloroquine.
Indomethacin: (Minor) Indomethacin may compete with penicillin for renal tubular secretion, increasing penicillin serum concentrations. This combination should be used with caution and patients monitored for increased side effects.
Lansoprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Lansoprazole; Amoxicillin; Clarithromycin: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Lesinurad; Allopurinol: (Minor) Use of ampicillin with allopurinol can increase the incidence of drug-related skin rash.
Leuprolide; Norethindrone: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Levonorgestrel: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Levonorgestrel; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Mafenide: (Minor) Sulfonamides may compete with ampicillin for renal tubular secretion, increasing ampicillin serum concentrations. Use this combination with caution, and monitor patients for increased side effects.
Magnesium Salicylate: (Minor) Due to high protein binding, salicylates could be displaced from binding sites, or could displace other highly protein-bound drugs such as penicillins, and sulfonamides. An enhanced effect of the displaced drug may occur.
Methotrexate: (Major) Avoid concomitant use of methotrexate with penicillins due to the risk of severe methotrexate-related adverse reactions. If concomitant use is unavoidable, closely monitor for adverse reactions.
Naproxen; Esomeprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Norethindrone: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Norethindrone; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic

use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Norgestimate; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Norgestrel: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Omeprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Omeprazole; Amoxicillin; Rifabutin: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Omeprazole; Sodium Bicarbonate: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Oral Contraceptives: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Pantoprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Probenecid: (Minor) Probenecid competitively inhibits renal tubular secretion and causes higher, prolonged serum levels of penicillins. In general, this pharmacokinetic interaction is not harmful and can be used therapeutically if needed.
Probenecid; Colchicine: (Minor) Probenecid competitively inhibits renal tubular secretion and causes higher, prolonged serum levels of penicillins. In general, this pharmacokinetic interaction is not harmful and can be used therapeutically if needed.
Proton pump inhibitors: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Rabeprazole: (Major) Proton pump inhibitors (PPIs) have long-lasting effects on the secretion of gastric acid. For enteral ampicillin, whose bioavailability is influenced by gastric pH, the concomitant administration of PPIs can exert a significant effect on ampicillin absorption.
Relugolix; Estradiol; Norethindrone acetate: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Salsalate: (Minor) Due to high protein binding, salicylates could be displaced from binding sites or could displace other highly protein-bound drugs such as penicillins. An enhanced effect of the displaced drug may occur.
Segesterone Acetate; Ethinyl Estradiol: (Moderate) It would be prudent to recommend alternative or additional contraception when oral contraceptives (OCs) are used in conjunction with antibiotics. It was previously thought that antibiotics may decrease the effectiveness of OCs containing estrogens due to stimulation of metabolism or a reduction in enterohepatic circulation via changes in GI flora. One retrospective study reviewed the literature to determine the effects of oral antibiotics on the pharmacokinetics of contraceptive estrogens and progestins, and also examined clinical studies in which the incidence of pregnancy with OCs and antibiotics was reported. It was concluded that the antibiotics ampicillin, ciprofloxacin, clarithromycin, doxycycline, metronidazole, ofloxacin, roxithromycin, temafloxacin, and tetracycline did not alter plasma concentrations of OCs. Antituberculous drugs (e.g., rifampin) were the only agents associated with OC failure and pregnancy. Based on the study results, these authors recommended that back-up contraception may not be necessary if OCs are used reliably during oral antibiotic use. Another review concurred with these data, but noted that individual patients have been identified who experienced significant decreases in plasma concentrations of combined OC components and who appeared to ovulate; the agents most often associated with these changes were rifampin, tetracyclines, and penicillin derivatives. These authors concluded that because females most at risk for OC failure or noncompliance may not be easily identified and the true incidence of such events may be under-reported, and given the serious consequence of unwanted pregnancy, that recommending an additional method of contraception during short-term antibiotic use may be justified. During long-term antibiotic administration, the risk for drug interaction with OCs is less clear, but alternative or additional contraception may be advisable in selected circumstances. Data regarding progestin-only contraceptives or for newer combined contraceptive deliveries (e.g., patches, rings) are not available.
Sodium Benzoate; Sodium Phenylacetate: (Moderate) Antibiotics that undergo tubular secretion such as penicillins may compete with phenylacetlyglutamine and hippuric acid for active tubular secretion. The overall usefulness of sodium benzoate; sodium phenylacetate is due to the excretion of its metabolites. An increase in metabolite concentrations could contribute to failed treatment and worsening of the patient's clinical status. This combination should be used with caution.
Sodium picosulfate; Magnesium oxide; Anhydrous citric acid: (Major) Prior or concomitant use of antibiotics with sodium picosulfate; magnesium oxide; anhydrous citric acid may reduce efficacy of the bowel preparation as conversion of sodium picosulfate to its active metabolite bis-(p-hydroxy-phenyl)-pyridyl-2-methane (BHPM) is mediated by colonic bacteria. If possible, avoid coadministration. Certain antibiotics (i.e., tetracyclines and quinolones) may chelate with the magnesium in sodium picosulfate; magnesium oxide; anhydrous citric acid solution. Therefore, these antibiotics should be taken at least 2 hours before and not less than 6 hours after the administration of sodium picosulfate; magnesium oxide; anhydrous citric acid solution.
Sulfadiazine: (Minor) Sulfonamides may compete with ampicillin for renal tubular secretion, increasing ampicillin serum concentrations. Use this combination with caution, and monitor patients for increased side effects.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Minor) Sulfonamides may compete with ampicillin for renal tubular secretion, increasing ampicillin serum concentrations. Use this combination with caution, and monitor patients for increased side effects.
Sulfasalazine: (Minor) Sulfonamides may compete with ampicillin for renal tubular secretion, increasing ampicillin serum concentrations. Use this combination with caution, and monitor patients for increased side effects.
Sulfonamides: (Minor) Sulfonamides may compete with ampicillin for renal tubular secretion, increasing ampicillin serum concentrations. Use this combination with caution, and monitor patients for increased side effects.
Tetracyclines: (Minor) Consider additional monitoring or alternative antimicrobial therapy for patients with infections in which clinical response is highly dependent upon the rapid, bactericidal activity of penicillins. Bacterostatic antibacterials like tetracyclines may antagonize the bactericidal effects of penicillins which may reduce their efficacy. The clinical relevance of this interaction is poorly defined and for many infections the benefits of combination therapy are likely to outweigh the potential risks.
Typhoid Vaccine: (Major) Antibiotics which possess bacterial activity against salmonella typhi organisms may interfere with the immunological response to the live typhoid vaccine. Allow 24 hours or more to elapse between the administration of the last dose of the antibiotic and the live typhoid vaccine.
Warfarin: (Moderate) The concomitant use of warfarin with many classes of antibiotics, including penicillins, may result in an increased INR thereby potentiating the risk for bleeding. Inhibition of vitamin K synthesis due to alterations in the intestinal flora may be a mechanism; however, concurrent infection is also a potential risk factor for elevated INR. Monitor patients for signs and symptoms of bleeding. Additionally, increased monitoring of the INR, especially during initiation and upon discontinuation of the antibiotic, may be necessary.

Ampicillin/Ampicillin Sodium Intramuscular Inj Pwd F/Sol: 1g, 2g, 10g, 250mg, 500mg
Ampicillin/Ampicillin Sodium Intravenous Inj Pwd F/Sol: 1g, 2g, 10g, 125mg, 250mg, 500mg
Ampicillin/Ampicillin trihydrate/Principen Oral Cap: 250mg, 500mg

Adults

2 g/day PO. 200 mg/kg/day IV/IM per FDA-approved product labeling (Max: 12 g/day).

Geriatric

2 g/day PO. 200 mg/kg/day IV/IM per FDA-approved product labeling (Max: 12 g/day).

Adolescents

100 mg/kg/day PO (Max: 2 g/day); 200 mg/kg/day IV/IM per FDA-approved product labeling; however, doses up to 400 mg/kg/day IV (Max: 12 g/day) have been used off-label for serious infections.

Children

100 mg/kg/day PO (Max: 2 g/day); 200 mg/kg/day IV/IM per FDA-approved product labeling; however, doses up to 400 mg/kg/day IV (Max: 12 g/day) have been used off-label for serious infections.

Infants

100 mg/kg/day PO; 200 mg/kg/day IV/IM per FDA-approved product labeling; however, doses up to 400 mg/kg/day IV have been used off-label for serious infections.

Neonates

older than 7 days: 150 mg/kg/day IV/IM per FDA-approved product labeling; however, doses up to 300 mg/kg/day IV have been used off-label for serious infections.
0 to 7 days and older than 34 weeks gestation: 150 mg/kg/day IV/IM per FDA-approved product labeling; however, doses up to 300 mg/kg/day IV have been used off-label for serious infections.
0 to 7 days and 34 weeks gestation or younger: 100 mg/kg/day IV/IM per FDA-approved product labeling; however, doses up to 300 mg/kg/day IV have been used off-label for serious infections.

Beta-lactam antibiotics such as ampicillin are mainly bactericidal. Like other penicillins, ampicillin inhibits the third and final stage of bacterial cell wall synthesis by preferentially binding to specific penicillin-binding proteins (PBPs) that are located inside the bacterial cell wall. Penicillin-binding proteins are responsible for several steps in the synthesis of the cell wall and are found in quantities of several hundred to several thousand molecules per bacterial cell. Penicillin-binding proteins vary among different bacterial species. Thus, the intrinsic activity of ampicillin, as well as the other penicillins, against a particular organism depends on their ability to gain access to and bind with the necessary PBP. Like all beta-lactam antibiotics, ampicillin's ability to interfere with PBP-mediated cell wall synthesis ultimately leads to cell lysis. Lysis is mediated by bacterial cell wall autolytic enzymes (i.e., autolysins). The relationship between PBPs and autolysins is unclear, but it is possible that the beta-lactam antibiotic interferes with an autolysin inhibitor. Prevention of the autolysin response to beta-lactam antibiotic exposure through loss of autolytic activity (mutation) or inactivation of autolysin (low-medium pH) by the microorganism can lead to tolerance to the beta-lactam antibiotic resulting in bacteriostatic activity.
 
The susceptibility interpretive criteria for ampicillin are delineated by pathogen. The MICs are defined for Enterobacterales and Vibrio sp. as susceptible at 8 mcg/mL or less, intermediate at 16 mcg/mL, and resistant at 32 mcg/mL or more (based on a dosage regimen of 2 g IV/IM every 4 to 6 hours, or 500 mg PO every 6 hours for salmonellosis, shigellosis, or uncomplicated urinary tract infection (UTI) due to E. coli and P. mirabilis). The MICs are defined for Enterococcus sp. as susceptible at 8 mcg/mL or less and resistant at 16 mcg/mL or more (based on a dosage regimen of 2 g IV/IM every 4 to 6 hours, or 500 mg PO every 6 hours for uncomplicated UTI). The MICs are defined for H. influenzae, H. parainfluenzae, Aggregatibacter sp., Cardiobacterium sp., E. corrodens, Kingella sp., and Lactococcus sp. as susceptible at 1 mcg/mL or less, intermediate at 2 mcg/mL, and resistant at 4 mcg/mL or more. H. influenzae and H. parainfluenzae breakpoints when used for meningitis are based on a dosage regimen of 2 g IV/IM every 4 hours. The MICs are defined for Streptococcus sp. beta-hemolytic group and E. rhusiopathiae as susceptible at 0.25 mcg/mL or less. The MICs are defined for Streptococcus sp. viridans group, Abiotrophia sp., and Granulicatella sp. as susceptible at 0.25 mcg/mL or less, intermediate at 0.5 to 4 mcg/mL, and resistant at 8 mcg/mL or more. Non-meningitis S. pneumoniae that are susceptible to penicillin are predictably sensitive to ampicillin. The MICs are defined for N. meningitidis as susceptible at 0.12 mcg/mL or less, intermediate at 0.25 to 1 mcg/mL, and resistant at 2 mcg/mL or more (based on a dosage regimen of 2 g IV/IM every 4 hours). The MICs are defined for anaerobes as susceptible at 0.5 mcg/mL or less, intermediate at 1 mcg/mL, and resistant at 2 mcg/mL or more. The MIC are defined for L. monocytogenes as susceptible at 2 mcg/mL or less. The MICs are defined for Lactobacillus sp., Leuconostoc sp., and Pediococcus sp. as susceptible at 8 mcg/mL or less. The MICs are defined for Pasteurella sp. as susceptible at 0.5 mcg/mL or less. The MICs are defined for Bacillus sp. (excluding B. anthracis) and related genera as susceptible at 0.25 mcg/mL or less and resistant at 0.5 mcg/mL or more.

Ampicillin is administered orally and parenterally by intravenous or intramuscular routes. Ampicillin is the least serum-bound of all the penicillins, averaging roughly 20% compared to approximately 60% to 90% for other penicillins. The drug is distributed into the lungs, liver, gallbladder, appendix, maxillary sinus, prostate, and other tissues. The drug also distributes very well into various body fluids, such as skin blisters, middle ear effusions, bronchial secretions, urine, and pleural, peritoneal, and synovial fluids. Therapeutic concentrations are attained within the cerebral spinal fluid (CSF) in the presence of inflammation. The drug does cross the placenta. Approximately 10% of an ampicillin dose is metabolized to inactive derivatives. Parent drug and metabolites are excreted into the urine primarily via tubular secretion and glomerular filtration. A small percentage is excreted in breast milk. In patients with normal renal function, the elimination half-life of ampicillin is 1 to 1.5 hours.
 
Affected cytochrome P450 isoenzymes: none

Oral Route

Approximately 30% to 55% of an oral dose of ampicillin is absorbed, significantly less than for amoxicillin. Peak serum levels of ampicillin occur within 1 to 2 hours after an oral dose. Food in the stomach inhibits the rate and extent of absorption. Oral administration should be either 1 hour prior to or 2 hours after a meal for maximal absorption.

Intravenous Route

Peak serum concentrations of ampicillin occur almost immediately after a 15-minute intravenous (IV) infusion. After a 2,000-mg ampicillin dose in adults, peak ampicillin serum concentrations range roughly 80 to 150 mcg/mL. Peak ampicillin concentrations are roughly 40 to 70 mcg/mL after administration of 1,000 mg ampicillin.

Intramuscular Route

Peak serum concentrations of ampicillin occur within 1 hour after an intramuscular (IM) dose. After an IM injection of 1,000 mg ampicillin to adults, peak ampicillin serum concentrations ranging from 8 to 37 mcg/mL are attained.

Pregnancy

Ampicillin is classified in FDA pregnancy category B. Animal data reveal no teratogenic effects. While ampicillin should be used with caution in pregnancy, penicillins are usually considered safe during pregnancy when clearly needed.

Penicillins, including ampicillin, are excreted in breast milk in small amounts. The manufacturer recommends caution with the use of ampicillin during nursing. However, unless the infant is allergic to penicillins, breast-feeding is generally safe during maternal ampicillin therapy. Breast milk concentrations range from 0.015—1.67 mcg/mL with a milk:plasma ratio of 0.02—0.525. Penicillins may cause diarrhea (due to disruption of GI flora), candidiasis, and skin rash in the breast-feeding infant. The infant should be observed for potential effects. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.