Dibenzyline

Other Cardiovascular Agents

Hazardous Drugs Classification
NIOSH 2016 List: Group 2
NIOSH (Draft) 2020 List: Table 2
Observe and exercise appropriate precautions for handling, preparation, administration, and disposal of hazardous drugs
Use gloves to handle. Cutting, crushing, or otherwise manipulating tablets/capsules will increase exposure and require additional protective equipment. Oral liquid drugs require double chemotherapy gloves and protective gown; may require eye/face protection.

To minimize GI irritation, administer with food or in divided doses.

orthostatic hypotension / Delayed / Incidence not known
sinus tachycardia / Rapid / Incidence not known
ejaculation dysfunction / Delayed / Incidence not known
gastritis / Delayed / Incidence not known

nasal congestion / Early / Incidence not known
miosis / Early / Incidence not known
dizziness / Early / Incidence not known
weakness / Early / Incidence not known
fatigue / Early / Incidence not known
drowsiness / Early / Incidence not known

Dibenzyline

Rx

Alpha-adrenergic antagonist; particularly effective in smooth muscle and exocrine glands
Useful in the treatment of sweating and hypertension associated with pheochromocytoma and for certain peripheral vasospastic conditions

Initially, 10 mg PO twice daily. Then increase by 10-mg increments every other day to a maintenance dose of 20 to 40 mg PO, given 2 to 3 times daily. Some patients may require higher doses.

Initially, 0.2 mg/kg PO once daily (Max: 10 mg). Increase dose every 4 days by 0.2 mg/kg/day increments. Usual maintenance dosage is 0.4 to 1.2 mg/kg/day, given in 3 to 4 divided doses. Doses up to 2 to 4 mg/kg/day have been used.

10 to 20 mg/day PO.

10 to 20 mg/day PO.

†Indicates off-label use

Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.

Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.

Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acetaminophen; Dextromethorphan; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acetaminophen; Dichloralphenazone; Isometheptene: (Major) Sympathomimetics can antagonize the antihypertensive effects of adrenergic agonists when administered concomitantly. Patients should be monitored for loss of blood pressure control.
Acetaminophen; Guaifenesin; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acrivastine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Aldesleukin, IL-2: (Moderate) Phenoxybenzamine may potentiate the hypotension seen with aldesleukin, IL-2.
Alemtuzumab: (Moderate) Alemtuzumab may cause hypotension. Careful monitoring of blood pressure and hypotensive symptoms is recommended especially in patients with ischemic heart disease and in patients on antihypertensive agents.
Alfuzosin: (Major) Alfuzosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between alfuzosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Alprostadil: (Minor) The concomitant use of systemic alprostadil injection and antihypertensive agents, such as phenoxybenzamine, may cause additive hypotension. Caution is advised with this combination. Systemic drug interactions with the urethral suppository (MUSE) or alprostadil intracavernous injection are unlikely in most patients because low or undetectable amounts of the drug are found in the peripheral venous circulation following administration. In those men with significant corpora cavernosa venous leakage, hypotension might be more likely. Use caution with in-clinic dosing for erectile dysfunction (ED) and monitor for the effects on blood pressure. In addition, the presence of medications in the circulation that attenuate erectile function may influence the response to alprostadil. However, in clinical trials with alprostadil intracavernous injection, anti-hypertensive agents had no apparent effect on the safety and efficacy of alprostadil.
Ambrisentan: (Moderate) Phenoxybenzamine is an antagonist at alpha-receptors. The hypotensive effects of phenoxybenzamine can be additive with those of other antihypertensive agents.
Amifostine: (Major) Patients receiving alpha-blockers should be closely monitored during amifostine infusions due to additive effects. Patients receiving amifostine at doses recommended for chemotherapy should have antihypertensive therapy interrupted 24 hours preceding administration of amifostine. If the antihypertensive cannot be stopped, patients should not receive amifostine.
Amobarbital: (Moderate) Concurrent use of amobarbital with antihypertensive agents may lead to hypotension. Monitor for decreases in blood pressure during times of coadministration.
Amphetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Amphetamine; Dextroamphetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Amphetamines: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Apomorphine: (Moderate) Use of phenoxybenzamine and apomorphine together can increase the hypotensive effects of apomorphine. Monitor blood pressure regularly during use of this combination.
Apraclonidine: (Minor) Alpha blockers as a class may reduce heart rate and blood pressure. While no specific drug interactions have been identified with systemic agents and apraclonidine during clinical trials, it is theoretically possible that additive blood pressure reductions could occur when apraclonidine is combined with the use of antihypertensive agents. Patients using cardiovascular drugs concomitantly with apraclonidine should have their pulse and blood pressure monitored periodically.
Aripiprazole: (Minor) Aripiprazole may enhance the hypotensive effects of antihypertensive agents.
Articaine; Epinephrine: (Moderate) Alpha-blockers antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by an alpha-blocker, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Asenapine: (Moderate) Secondary to alpha-blockade, asenapine can produce vasodilation that may result in additive effects during concurrent use of antihypertensive agents. The potential reduction in blood pressure can precipitate orthostatic hypotension and associated dizziness, tachycardia, and syncope. If concurrent use of asenapine and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
Avanafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of avanafil. Conversely, patients already receiving an optimized dose of avanafil should be started on the lowest dose of the alpha-blocker; increases in the alpha-blocker dose should be done in a stepwise fashion. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of avanafil and alpha-blockers.
Baclofen: (Moderate) Baclofen has been associated with hypotension. Concurrent use with baclofen and antihypertensive agents may result in additive hypotension. Dosage adjustments of the antihypertensive medication may be required.
Benzphetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Beta-blockers: (Moderate) Orthostatic hypotension may be more likely if beta-blockers are coadministered with alpha-blockers.
Bortezomib: (Moderate) Patients on antihypertensive agents receiving bortezomib treatment may require close monitoring of their blood pressure and dosage adjustment of their medication. During clinical trials of bortezomib, hypotension was reported in roughly 12 percent of patients.
Brexpiprazole: (Moderate) Due to brexpiprazole's antagonism at alpha 1-adrenergic receptors, the drug may enhance the hypotensive effects of alpha-blockers and other antihypertensive agents.
Bromocriptine: (Minor) Bromocriptine has only minimal affinity for adrenergic receptors; however, hypotension can occur during bromocriptine administration. Orthostatic hypotension occurs in 6% of acromegaly patients receiving the drug. Hypotension occurred frequently (approximately 30%) in postpartum studies, which in rare cases approached a decline in supine pressure of almost 60 mmHg. It is unknown if bromocriptine is the exact cause of this effect. However, the drug should be used cautiously with other medications known to lower blood pressure such as antihypertensive agents. Monitoring of blood pressure should be considered, especially during the initial weeks of concomitant therapy.
Brompheniramine; Dextromethorphan; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Brompheniramine; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Brompheniramine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Bupivacaine; Epinephrine: (Moderate) Alpha-blockers antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by an alpha-blocker, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Cabergoline: (Moderate) Cabergoline should be used cautiously with antihypertensive agents, including alpha-blockers. Cabergoline has been associated with hypotension. Initial doses higher than 1 mg may produce orthostatic hypotension. It may be advisable to monitor blood pressure.
Carbidopa; Levodopa: (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects.
Carbidopa; Levodopa; Entacapone: (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects.
Cariprazine: (Moderate) Orthostatic vital signs should be monitored in patients who are at risk for hypotension, such as those receiving cariprazine in combination with antihypertensive agents. Atypical antipsychotics may cause orthostatic hypotension and syncope, most commonly during treatment initiation and dosage increases. Patients should be informed about measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning, or rising slowly from a seated position. Consider a cariprazine dose reduction if hypotension occurs.
Cetirizine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Chlorpheniramine; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Chlorpheniramine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Clofarabine: (Moderate) Concomitant use of clofarabine, a substrate of OCT1 and OCT2, and phenoxybenzamine, an inhibitor of OCT1 and OCT2, may result in increased clofarabine levels. Therefore, monitor for signs of clofarabine toxicity such as gastrointestinal toxicity (e.g., nausea, vomiting, diarrhea, mucosal inflammation), hematologic toxicity, and skin toxicity (e.g., hand and foot syndrome, rash, pruritus) in patients also receiving OCT1 and OCT2 inhibitors.
Clozapine: (Moderate) Clozapine used concomitantly with the antihypertensive agents can increase the risk and severity of hypotension by potentiating the effect of the antihypertensive drug.
Cocaine: (Major) Phenoxybenzamine would likely antagonize the sympathomimetic effects of cocaine.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Codeine; Phenylephrine; Promethazine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Co-Enzyme Q10, Ubiquinone: (Moderate) Co-enzyme Q10, ubiquinone (CoQ10) may lower blood pressure. CoQ10 use in combination with antihypertensive agents may lead to additional reductions in blood pressure in some individuals. Patients who choose to take CoQ10 concurrently with antihypertensive medications should receive periodic blood pressure monitoring. Patients should be advised to inform their prescriber of their use of CoQ10.
Desloratadine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Desogestrel; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Dexbrompheniramine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Dextroamphetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Dextromethorphan; Quinidine: (Moderate) Quinidine can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents due to the potential for additive hypotension.
Diazoxide: (Moderate) Additive hypotensive effects can occur with the concomitant administration of diazoxide with other antihypertensive agents. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly. The manufacturer advises that IV diazoxide should not be administered to patients within 6 hours of receiving other antihypertensive agents.
Diethylpropion: (Major) Diethylpropion has vasopressor effects and may limit the benefit of alpha-blockers. Although leading drug interaction texts differ in the potential for an interaction between diethylpropion and this group of antihypertensive agents, these effects are likely to be clinically significant and have been described in hypertensive patients on these medications.
Diphenhydramine; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Dobutamine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Dopamine: (Major) In general, alpha-blockers should not be used during dopamine infusion. The undesired peripheral vasoconstriction observed with high-dose dopamine is opposed by alpha-adrenergic blockers. The renal, mesenteric, or cerebral vasodilatory properties resulting from dopaminergic-receptor stimulation are not affected by alpha-blockers .
Drospirenone; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Duloxetine: (Moderate) Orthostatic hypotension and syncope have been reported during duloxetine administration. The concurrent administration of antihypertensive agents and duloxetine may increase the risk of hypotension. Monitor blood pressure if the combination is necessary.
Dutasteride; Tamsulosin: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Ephedrine: (Moderate) Carefully monitor blood pressure in patients who have received both ephedrine and alpha-blockers; alpha-blockers antagonize the pressor effect of ephedrine.
Ephedrine; Guaifenesin: (Moderate) Carefully monitor blood pressure in patients who have received both ephedrine and alpha-blockers; alpha-blockers antagonize the pressor effect of ephedrine.
Epinephrine: (Moderate) Alpha-blockers antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by an alpha-blocker, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Epoprostenol: (Minor) Epoprostenol can have additive effects when administered with other antihypertensive agents, including alpha-blockers. These effects can be used to therapeutic advantage, but dosage adjustments may be necessary.
Estradiol: (Minor) Estrogens can induce fluid retention and may increase blood pressure in some patients; patients who are receiving antihypertensive agents concurrently with hormonal contraceptives should be monitored to confirm that the desired antihypertensive effect is being obtained.
Ethanol: (Major) Advise patients to avoid alcohol consumption while taking alpha-blockers. Concomitant use may increase the risk for hypotension.
Ethinyl Estradiol; Norelgestromin: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Ethinyl Estradiol; Norethindrone Acetate: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Ethinyl Estradiol; Norgestrel: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Ethynodiol Diacetate; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Etomidate: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
Etonogestrel; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Fexofenadine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Finasteride; Tadalafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest recommended dose of tadalafil. Conversely, patients already receiving an optimized dose of tadalafil should be started on the lowest dose of the alpha-blocker; increases in the alpha-blocker dose should be done in stepwise fashion. When tadalafil is used for benign prostatic hypertrophy (BPH), discontinue alpha-blocker therapy at least 1 day prior to initiating tadalafil therapy. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of tadalafil and an alpha-blocker.
Fish Oil, Omega-3 Fatty Acids (Dietary Supplements): (Moderate) High doses of fish oil supplements may produce a blood pressure lowering effect. It is possible that additive reductions in blood pressure may be seen when fish oils are used in a patient already taking antihypertensive agents.
General anesthetics: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
Guaifenesin; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Guaifenesin; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Haloperidol: (Moderate) In general, haloperidol should be used cautiously with antihypertensive agents due to the possibility of additive hypotension.
Hydralazine; Isosorbide Dinitrate, ISDN: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
Hydrocodone; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Ibuprofen; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Iloperidone: (Moderate) Secondary to alpha-blockade, iloperidone can produce vasodilation that may result in additive effects during concurrent use with antihypertensive agents. The potential reduction in blood pressure can precipitate orthostatic hypotension and associated dizziness, tachycardia, and syncope. If concurrent use of iloperidone and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
Iloprost: (Moderate) Further reductions in blood pressure may occur when inhaled iloprost is administered to patients receiving other antihypertensive agents.
Intravenous Lipid Emulsions: (Moderate) High doses of fish oil supplements may produce a blood pressure lowering effect. It is possible that additive reductions in blood pressure may be seen when fish oils are used in a patient already taking antihypertensive agents.
Isocarboxazid: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy with antihypertensives such as alpha-blockers. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.
Isoflurane: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
Isoproterenol: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Isosorbide Dinitrate, ISDN: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
Isosorbide Mononitrate: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
Ketamine: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
Levodopa: (Moderate) Concomitant use of antihypertensive agents with levodopa can result in additive hypotensive effects.
Levonorgestrel; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Lidocaine; Epinephrine: (Moderate) Alpha-blockers antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by an alpha-blocker, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Lisdexamfetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Lofexidine: (Major) Because the central alpha-2 agonist effects of lofexidine can cause hypotension and orthostasis, the drug should be avoided, if possible, in combination with other medications that can significantly decrease blood pressure such as the antihypertensive alpha-blockers. If coadministration is required, blood pressure should be monitored, particularly after dose changes of either agent. Adjustments should be made as clinically indicated. Patients being given lofexidine in an outpatient setting should be capable of and instructed on self-monitoring for hypotension, orthostasis, bradycardia, and associated symptoms. If clinically significant or symptomatic hypotension and/or bradycardia occur, the next dose of lofexidine should be reduced in amount, delayed, or skipped.
Loratadine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Lurasidone: (Moderate) Due to the antagonism of lurasidone at alpha-1 adrenergic receptors, the drug may enhance the hypotensive effects of alpha-blockers and other antihypertensive agents. If concurrent use of lurasidone and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
Methamphetamine: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Methohexital: (Moderate) Concurrent use of methohexital and alpha-blockers increases the risk of developing hypotension and hypothermia.
Methylphenidate Derivatives: (Moderate) Periodic evaluation of blood pressure is advisable during concurrent use of methylphenidate derivatives and antihypertensive agents, particularly during initial coadministration and after dosage increases of methylphenidate. Methylphenidates can reduce the hypotensive effect of antihypertensive agents such as alpha-blockers.
Midodrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Milrinone: (Moderate) Concurrent administration of antihypertensive agents could lead to additive hypotension when administered with milrinone. Titrate milrinone dosage according to hemodynamic response.
Naproxen; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Nesiritide, BNP: (Major) The potential for hypotension may be increased when coadministering nesiritide with antihypertensive agents.
Niacin, Niacinamide: (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. This effect is of particular concern in the setting of acute myocardial infarction, unstable angina, or other acute hemodynamic compromise.
Niacin; Simvastatin: (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. This effect is of particular concern in the setting of acute myocardial infarction, unstable angina, or other acute hemodynamic compromise.
Nicotine: (Moderate) Nicotine use may reduce the clinical effects of the alpha-blockers. If significant changes in nicotine intake occur, the dosages of these drugs may need adjustment.
Nitrates: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
Nitroglycerin: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
Nitroprusside: (Moderate) Additive hypotensive effects may occur when nitroprusside is used concomitantly with other antihypertensive agents. Dosages should be adjusted carefully, according to blood pressure.
Nonsteroidal antiinflammatory drugs: (Moderate) If nonsteroidal anti-inflammatory drugs (NSAIDs) and an antihypertensive drug are concurrently used, carefully monitor the patient for signs and symptoms of renal insufficiency and blood pressure control. Doses of antihypertensive medications may require adjustment in patients receiving concurrent NSAIDs. NSAIDs, to varying degrees, have been associated with an elevation in blood pressure. This effect is most significant in patients receiving concurrent antihypertensive agents and long-term NSAID therapy. NSAIDs cause a dose-dependent reduction in prostaglandin formation, which may result in a reduction in renal blood flow leading to renal insufficiency and an increase in blood pressure that are often accompanied by peripheral edema and weight gain. Patients who rely upon renal prostaglandins to maintain renal perfusion may have acute renal blood flow reduction with NSAID usage. Elderly patients may be at increased risk of adverse effects from combined long-term NSAID therapy and antihypertensive agents, especially diuretics, due to age-related decreases in renal function and an increased risk of stroke and coronary artery disease.
Norepinephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly. Also, because norepinephrine is an alpha-adrenergic agonist, drugs with alpha-blocking activity such as alpha-blockers directly counteract the vasopressor effects of norepinephrine.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Norethindrone; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Norgestimate; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Olanzapine: (Moderate) Olanzapine may induce orthostatic hypotension and thus enhance the effects of antihypertensive agents.
Olanzapine; Fluoxetine: (Moderate) Olanzapine may induce orthostatic hypotension and thus enhance the effects of antihypertensive agents.
Olanzapine; Samidorphan: (Moderate) Olanzapine may induce orthostatic hypotension and thus enhance the effects of antihypertensive agents.
Oxymetazoline: (Major) Caution is advised when administering phenoxybenzamine with oxymetazoline. Phenoxybenzamine, an alpha adrenergic blocker, would likely antagonize the sympathomimetic effects of oxymetazoline, alpha adrenergic agonists; thereby reducing the effectiveness of oxymetazoline. Clinicians should note that phenoxybenzamine has a long duration of action and its effects may persist for several days after it has been discontinued.
Pentoxifylline: (Moderate) Pentoxifylline has been used concurrently with antihypertensive drugs (beta blockers, diuretics) without observed problems. Small decreases in blood pressure have been observed in some patients treated with pentoxifylline; periodic systemic blood pressure monitoring is recommended for patients receiving concomitant antihypertensives. If indicated, dosage of the antihypertensive agents should be reduced.
Phendimetrazine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Phenelzine: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy with antihypertensives such as alpha-blockers. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.
Phentermine: (Moderate) Monitor for desired antihypertensive effect of alpha-blockers when administered with phentermine, Sympathomimetics like phentermine can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Phentermine; Topiramate: (Moderate) Monitor for desired antihypertensive effect of alpha-blockers when administered with phentermine, Sympathomimetics like phentermine can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Prilocaine; Epinephrine: (Moderate) Alpha-blockers antagonize the pressor effects of epinephrine. Do not use epinephrine to counteract hypotension caused by an alpha-blocker, as a reversal of the pressor effect of epinephrine may result in paradoxical further lowering of blood pressure.
Procainamide: (Moderate) Procainamide can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents. Intravenous administration of procainamide is more likely to cause hypotensive effects.
Promethazine; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Propofol: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Pseudoephedrine; Triprolidine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Quinidine: (Moderate) Quinidine can decrease blood pressure and should be used cautiously in patients receiving antihypertensive agents due to the potential for additive hypotension.
Rasagiline: (Moderate) Additive hypotensive effects may be seen when monoamine oxidase inhibitors (MAOIs) are combined with antihypertensives. Careful monitoring of blood pressure is suggested during concurrent therapy with antihypertensives such as alpha-blockers. Patients should be instructed to rise slowly from a sitting position, and to report syncope or changes in blood pressure or heart rate to their health care provider.
Risperidone: (Moderate) Risperidone may induce orthostatic hypotension and thus enhance the hypotensive effects of antihypertensive agents. Lower initial doses or slower dose titration of risperidone may be necessary in patients receiving antihypertensive agents concomitantly.
Segesterone Acetate; Ethinyl Estradiol: (Minor) Estrogen-containing oral contraceptive may induce fluid retention and may increase blood pressure in some patients taking antihypertensive agents. Such patients should be monitored to confirm that the desired antihypertensive effect is being obtained.
Sevoflurane: (Moderate) General anesthetics can potentiate the hypotensive effects of antihypertensive agents.
Sildenafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of sildenafil. Conversely, patients already receiving an optimized dose of sildenafil should be started on the lowest dose of the alpha-blocker; increases in the alpha-blocker dose should be done in a stepwise fashion. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of sildenafil and an alpha-blocker.
Silodosin: (Major) Silodosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between silodosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Tadalafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest recommended dose of tadalafil. Conversely, patients already receiving an optimized dose of tadalafil should be started on the lowest dose of the alpha-blocker; increases in the alpha-blocker dose should be done in stepwise fashion. When tadalafil is used for benign prostatic hypertrophy (BPH), discontinue alpha-blocker therapy at least 1 day prior to initiating tadalafil therapy. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of tadalafil and an alpha-blocker.
Tamsulosin: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Tetrabenazine: (Moderate) Tetrabenazine may induce orthostatic hypotension and thus enhance the hypotensive effects of antihypertensive agents. Lower initial doses or slower dose titration of tetrabenazine may be necessary in patients receiving antihypertensive agents concomitantly.
Tetracaine: (Moderate) Local anesthetics may cause additive hypotension in combination with antihypertensive agents. Use extreme caution with the concomitant use of tetracaine and antihypertensive agents.
Thalidomide: (Moderate) Thalidomide and other agents that slow cardiac conduction such as alpha-blockers should be used cautiously due to the potential for additive bradycardia.
Thiothixene: (Moderate) Thiothixene should be used cautiously in patients receiving antihypertensive agents. Additive hypotensive effects are possible.
Tizanidine: (Moderate) Concurrent use of tizanidine with antihypertensive agents can result in significant hypotension. Caution is advised when tizanidine is to be used in patients receiving concurrent antihypertensive therapy.
Trandolapril; Verapamil: (Moderate) Additive pharmacodynamic effects are especially prominent when verapamil is co-administered with alpha-blockers or beta-blockers. The use of alpha-blockers with verapamil can lead to excessive hypotension.
Tranylcypromine: (Contraindicated) The use of hypotensive agents and tranylcypromine is contraindicated by the manufacturer of tranylcypromine because the effects of hypotensive agents may be markedly potentiated.
Trazodone: (Minor) Due to additive hypotensive effects, patients receiving antihypertensive agents concurrently with trazodone may have excessive hypotension. Decreased dosage of the antihypertensive agent may be required when given with trazodone.
Vardenafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on alpha-blocker therapy before initiating therapy with the lowest dose of vardenafil. Conversely, patients already receiving an optimized dose of vardenafil should be started on the lowest dose of the alpha-blocker; increases in the alpha-blocker dose should be done in a stepwise fashion. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of vardenafil and an alpha-blocker.
Verapamil: (Moderate) Additive pharmacodynamic effects are especially prominent when verapamil is co-administered with alpha-blockers or beta-blockers. The use of alpha-blockers with verapamil can lead to excessive hypotension.
Ziprasidone: (Minor) Ziprasidone is a moderate antagonist of alpha-1 receptors and may cause orthostatic hypotension with or without tachycardia, dizziness, or syncope. Additive hypotensive effects are possible if ziprasidone is used concurrently with antihypertensive agents.

Dibenzyline/Phenoxybenzamine/Phenoxybenzamine Hydrochloride Oral Cap: 10mg

Specific maximum dosage information is not available. Dosage should be based on efficacy and tolerance.

Specific maximum dosage information is not available. Dosage should be based on efficacy and tolerance.

Safety and efficacy have not been established.

Safety and efficacy have not been established, although doses up to 4 mg/kg/day PO have been used.

Phenoxybenzamine is a long-acting, nonselective, irreversible antagonist of alpha-adrenergic receptors. Like phentolamine, phenoxybenzamine antagonizes both alpha1- and alpha2-receptors. Prazosin, in contrast, is selective for only the alpha1-receptor. In addition, phenoxybenzamine blocks the reuptake of norepinephrine by presynaptic adrenergic nerve terminals and also blocks histamine, acetylcholine, and serotonin receptors.
 
Phenoxybenzamine increases blood flow to abdominal and mucosa viscera, the skin, and lowers both supine and erect blood pressures. It has no effect on the parasympathetic system. Like phentolamine, phenoxybenzamine reduces peripheral resistance via antagonism of the alpha1-receptors and possibly alpha2-receptors on vascular smooth muscle. Antagonism at alpha2-receptors cause cardiac stimulation due to an enhanced release of norepinephrine from sympathetic nerves. The most significant clinical effect of phenoxybenzamine is attenuation of catecholamine-induced vasoconstriction. Although phenoxybenzamine does not affect blood pressure in normal supine individuals, it does reduces blood pressure when sympathetic tone is high. The use of phenoxybenzamine can result in include cardiac stimulation caused by a decrease in peripheral resistance and an increase in cardiac output.

Phenoxybenamine is administered orally. Distribution is extensive because phenoxybenzamine is highly lipophilic and may accumulate in fatty tissues. Clinical effects can last up to 7 days after discontinuation of therapy. Elimination half-life is roughly 24 hours. The drug is metabolized by dealkylation to N-phenoxyisopropylbenzylamine. Both parent and metabolites are excreted in the urine and bile.

Oral absorption of phenoxybenzamine is variable; only about 20—30% of the drug is bioavailable. The onset of action is gradual and extends over a period of several hours after administration of fixed daily doses.

Studies have not been done in animals or humans to determine the effects on the fetus. The drug should be used in pregnancy only if clearly needed. The definitive treatment for pheochromocytoma is surgery, but in patients past 24 weeks gestation, problems with tumor accessibility may delay surgery. Pretreatment with an alpha-blocker, such as phenoxybenzamine or doxazosin, is recommended prior to surgical removal of the tumor to reduce maternal and fetal mortality. Phenoxybenzamine crosses the placenta and may briefly cause hypotension and respiratory depression in the neonate; thus, it is recommended to closely monitor neonates whose mothers were treated with phenoxybenzamine for the first 3 days of life. Phenoxybenzamine may briefly cause perinatal depression in the mother. 

It is not known whether phenoxybenzamine is excreted in human milk; the molecular weight of the drug indicates the drug may pass to the milk. Potential adverse effects to the nursing infant are unknown but might include hypotension. Alternate feeding options may deserve consideration. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions from phenoxybenzamine, a decision should be made whether to discontinue breast-feeding or to discontinue the drug, taking into account the importance of the drug to the mother.