Phenelzine Sulfate

A to Z Drug Facts

 Action Phenelzine blocks activity of enzyme MAO, thereby increasing monoamine (eg, epinephrine, norepinephrine, serotonin) concentrations in CNS.

 Indications Treatment of “atypical” (“nonendogenous” or “neurotic”) depression; management of depression in patients unresponsive to other antidepressant drugs. Unlabeled use(s): Treatment of bulimia; treatment of cocaine addiction; control of panic disorder with agoraphobia.

 Contraindications Hypersensitivity to MAO inhibitors; pheochromocytoma; CHF; abnormal liver function; history of liver disease; severe renal impairment; cerebrovascular defect; concurrent use of dextromethorphan or CNS depressants (eg, alcohol); sympathomimetic drugs (eg, amphetamine, dopamine, norepinephrine) or related drugs (eg, methyldopa); cardiovascular disease.

 Route/Dosage

ADULTS: PO 15 mg tid initially; may titrate up to 90 mg/day. Elderly should receive no more than 60 mg daily. After maximum benefit is achieved, dose can be slowly decreased over several weeks to maintenance dose. Doses as low as 15 mg q od may be used for maintenance.

 Interactions

Amine-containing foods: May cause severe hypertension or hemorrhagic strokes. Anorexiants: May cause exaggerated pharmacologic effects (eg, severe headaches, hypertension, hyperpyrexia) of anorexiants (amphetamines and related compounds). CNS depressants: May enhance CNS effects. Dextromethorphan: Concurrent use has been associated with severe reactions (eg, hyperpyrexia, hypotension, death). Fluoxetine, paroxetine, sertraline trazodone: Although data are limited, interactions comparable to those of the tricycle antidepressants and phenelzine may occur. Guanethidine: MAO inhibitors may antagonize the antihypertensive effect. Insulin, sulfonylureas: May enhance hypoglycemic action. Levodopa: May cause hypertensive reactions. Meperidine: May lead to severe reactions, including hypotension, convulsions, respiratory depression, and vascular collapse. Sympathomimetics: May cause severe headache, hypertensive crisis, and hyperpyrexia. Tricyclic antidepressants, buspirone, cyclobenzaprine, carbamazepine, maprotiline, guanethidine, CNS stimulants, tyramine: May lead to potentially fatal reactions, including seizures and hypertensive crisis; mental status changes, hyperthermia.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Orthostatic hypotension; edema; hypertensive crisis. CNS: Dizziness; headache; sleep disturbances; tremors; hyperflexemia; manic symptoms; convulsions; toxic delirium; coma. DERM: Rash; sweating; photosensitivity. EENT: Blurred vision; glaucoma. GI: Constipation; nausea; GI disturbances; anorexia. GU: Sexual dysfunction; urinary retention; incontinence. HEMA: Anemia; leukopenia; agranulocytosis; thrombocytopenia. HEPA: Fatal progressive necrotizing hepatocellular damage; elevated serum transaminases; hepatitis. META: Weight gain; hypermetabolic syndrome (eg, fever, tachycardia, rapid breathing, rigidity, metabolism, acidosis, coma); hypernatremia. OTHER: Transient respiratory and circulatory depression following electroconvulsive therapy.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Not recommended in patients < 16 yr. Elderly: Drug should be used cautiously in patients > 60 yr because of possibility of existing cerebral sclerosis with damaged vessels. If hypertension develops, the risk of stroke may be increased. Depression associated with drug abuse/alcoholism: Use with caution; increased risk of serious drug interactions. Epilepsy: May lower seizure threshold. Diabetes: May alter glucose control. Hypotension: Orthostatic hypotension is significant side effect and may lead to falling and changes in heart rate. Pyridoxine: Phenelzine may cause pyridoxine deficiency, with symptoms of numbness, paresthesias and edema. Supplements may be required. Suicidal patients: Strict supervision may be necessary in patients at risk.

 Administration/Storage

• Tablets may be crushed if patient is unable to swallow them whole.
• Do not give > 60 mg/day to elderly.
• Do not administer several days before surgery. If possible, discontinue 7 to 14 days before elective surgery.
• Wait 14 days after discontinuing tricyclic antidepressants, other MAO inhibitors, carbamazepine, maprotiline, guanethidine, paroxetine, sertraline cyclobenzaprine or CNS stimulants to administer this medication. Wait 5 wk after discontinuing fluoxetine before starting phenelzine.
• Do not administer unless patient has been on tyramine-free diet for ³ 2 to 3 days. Continue on this diet for 2 wk after discontinuation of MAOI.
• Store in tightly-closed container and protect from heat and light.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note CHF, cardiovascular disease, cerebrovascular disease, hypertension, abnormal liver or renal function, pheochromocytoma, or severe headaches.
• Monitor patient's lying and standing BP before initiating therapy.
• Monitor liver function if jaundice or other signs of liver dysfunction occur, discontinue drug and notify physician.
• Obtain baseline CBC and liver function tests.
• During initial therapy, monitor BP and pulse.
• Monitor I&O carefully until dosage is stabilized.
• Observe for onset of therapeutic effect (ie, improved mood, improved sleep patterns, socialization) in depressed patients in 7 to 14 days and full response in up to 6 wk.
• Continue to monitor potentially suicidal patients until they demonstrate definite significant, lasting improvement.
• Be alert for evidence of orthostatic hypotension, monitor orthostatic BP and report to physician.
• Monitor for signs of hypertensive crisis (eg, high BP, severe headache, palpitations, severe chest pain, sweating, nausea and vomiting, dilated pupils, photophobia). If signs occur, discontinue drug and notify physician. Have alpha-adrenergic blocking agent (eg, phentolamine) readily available to lower BP and external cooling mechanisms for hyperpyrexia.
• Monitor blood sugars of patients receiving insulin or other antidiabetic agents; coadministration may enhance hypoglycemic effect.

 Patient/Family Education

• Inform patient that it may be 4 wk before improvement in mood is noticed.
• Instruct patient that antidepressant medications will not make him or her high or elevate mood; antidepressants restore depressed people to normal state.
• Instruct patient to avoid sudden position changes to prevent orthostatic hypotension.
• Instruct patient that it is important to consult physician before taking any medication and that it is especially important to avoid otc cold, hay fever, or weight reduction preparations.
• Instruct patient to avoid tyramine- or tryptophan-containing foods while taking drug and for 2 wk after discontinuing medication. These are protein foods that are aged or fermented and include cheeses, pickled herring, liver, hard sausage (eg, Genoa salami or pepperoni), pods of broad beans, beer, red wine, yeast extract, yogurt, ginseng, soy sauce, bananas, raisins, and avocados. Advise patient to consult dietitian.
• Instruct patient to ingest caffeine and chocolate in moderation.
• Advise patient to weigh self 2 to 3 times weekly and report unusual gains.
• Instruct patient to stop taking phenelzine and to notify physician immediately if severe headache, severe chest pain, change in heart rate, photophobia, increased sweating, nausea and vomiting, or stiff or sore neck occurs.
• Advise patient not to use alcohol or any abuse drug.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts