Classifications: psychotherapeutic; antidepressant; monoamine oxidase (mao) inhibitor; Therapeutic: antidepressant; mao inhibitor
Pregnancy Category: C
15 mg tablets
Potent hydrazine (monoamine oxidase) MAO inhibitor. Antidepressant and diverse effects believed to be due to irreversible
inhibition of MAO, thereby permitting increased concentrations of endogenous epinephrine, norepinephrine, serotonin, and
dopamine within presynaptic neurons and at receptor sites. Also thought to inhibit hepatic microsomal drug-metabolizing
enzymes; thus it may intensify and prolong the effects of many drugs.
Antidepressant utilization of the drug is limited to individuals who do not respond well to other classes of antidepressants.
Termination of drug action depends on regeneration of MAO inhibitors, which occurs 23 wk after discontinuation of
Management of endogenous depression, depressive phase of manic-depressive psychosis, and severe exogenous (reactive) depression
not responsive to more commonly used therapy.
Hypersensitivity to MAO inhibitors; suicidal ideation; pheochromocytoma; hyperthyroidism; CHF, acute MI, cardiac arrhythmias,
hypertension, history of angina pectoris; cardiovascular or cerebrovascular disease; increased intracranial pressure; intracranial
bleeding; renal failure; impaired kidney function, hypernatremia; atonic colitis; glaucoma; history of frequent or severe
headaches; history of liver disease, abnormal liver function tests; alcoholism, alcohol intoxication; depression, accompanying
alcoholism or drug addiction; older adult or debilitated patients; paranoid schizophrenia; pregnancy (category C), lactation.
Safety in children <6 y of age is not established.
Epilepsy; pyloric stenosis; diabetes; manic-depressive states; agitated patients; schizophrenia or psychosis; seizures; suicidal
tendencies; chronic brain syndromes.
Route & Dosage
Adult: PO 15 mg t.i.d., rapidly increase to at least 60 mg/d, may need up to 90 mg/d
- Discontinue at least 10 d before elective surgery to allow time for recovery from MAO before anesthetics are given.
- Avoid rapid withdrawal of MAO inhibitors, particularly after high dosage, since a rebound effect may occur (e.g., headache,
excitability, hallucinations, and possibly depression).
- Store in tightly covered containers away from heat and light.
Adverse Effects (≥1%)Body as a Whole:
Dizziness or vertigo, headache, orthostatic hypotension,
drowsiness or insomnia,
, edema, tremors, twitching, akathisia, ataxia, hyperreflexia, faintness, hyperactivity, marked agitation,
anxiety, seizures, trismus, opisthotonos, respiratory depression, coma. CNS:
Mania, hypomania, confusion, memory impairment, delirium, hallucinations, euphoria, acute anxiety reaction, toxic precipitation
of schizophrenia, convulsions, peripheral neuropathy. CV: Hypertensive crisis
(intense occipital headache, palpitation, marked hypertension, stiff neck, nausea, vomiting, sweating, fever, photophobia,
dilated pupils, bradycardia or tachycardia, constricting chest pain, intracranial bleeding), hypotension or hypertension,
circulatory collapse. GI: Constipation, dry mouth, nausea,
weight gain. Hematologic:
Normocytic and normochromic anemia, leukopenia. Skin:
Hyperhidrosis, skin rash, photosensitivity. Special Senses:
Diagnostic Test Interference
Phenelzine may cause a slight false increase in serum bilirubin.
InteractionsDrug: tricyclic antidepressants
may cause hyperpyrexia, seizures; fluoxetine, sertraline, paroxetine
may cause serotonin syndrome
(see Appendix F); sympathomimetic agents
(e.g., amphetamine, phenylephrine, phenylpropanolamine
may cause hypertensive crisis; cns depressants
have additive CNS depressive effects; opiate analgesics
) may cause hypertensive crisis and circulatory collapse; buspirone,
hypertension; general anesthetics
, prolonged hypotensive and CNS depressant effects; hypertension, headache, hyperexcitability reported with dopamine, methyldopa, levodopa, tryptophan; metrizamide
may increase risk of seizures; hypotensive agents
have additive hypotensive effects. Food:
Aged meats or aged cheeses, protein extracts, sour cream, alcohol
, anchovies, liver, sausages, overripe figs, bananas, avocados,
chocolate, soy sauce, bean curd, natural yogurt, fava beanstyramine
-containing foodsmay precipitate hypertensive crisis. Avoid chocolate
or caffeine. Herbal: Ginseng, ephedra, ma huang, St. John's wort
may cause hypertensive crisis.
Readily absorbed from GI tract. Onset:
2 wk. Metabolism:
Rapidly metabolized. Elimination:
79% of metabolites excreted in urine in 96 h.
Assessment & Drug Effects
- Evaluate patient's BP in standing and recumbent positions. Prior to initiation of treatment.
- Monitor children, adolescents, and adults for changes in behavior that may indicate suicidality.
- Lab tests: Perform baseline CBC and liver function tests. Also perform periodic CBC and liver function tests during prolonged
or high-dose therapy.
- Monitor BP and pulse between doses when titrating initial dosages. Observe closely for evidence of adverse drug effects.
Thereafter, monitor at regular intervals throughout therapy.
- Report immediately if hypomania (exaggeration of motility, feelings, and ideas) occurs as depression improves. This reaction
may also appear at higher than recommended doses or with long-term therapy.
- Observe for and report therapeutic effectiveness of drug: Improvement in sleep pattern, appetite, physical activity, interest
in self and surroundings, as well as lessening of anxiety and bodily complaints.
- Observe patient with diabetes closely for S&S of hypoglycemia (see Appendix F). Patients on prolonged therapy should be checked
periodically for altered color perception, changes in fundi or visual fields. Changes in red-green vision may be the first
indication of eye damage.
Patient & Family Education
- Drug is usually discontinued if no therapeutic response occurs after 3 or 4 wk. Maximum antidepressant effects generally
appear in 26 wk and persist several weeks after drug withdrawal.
- Avoid self-medication. OTC preparations containing dextromethorphan, sympathomimetic agents, or antihistamines (e.g., cough,
cold, and hay fever remedies, appetite suppressants) can precipitate severe hypertensive reactions if taken during therapy
or within 23 wk after discontinuation of an MAO inhibitor.
- Report immediately to physician the onset of headache and palpitation, prodromal symptoms of hypertensive crisis or any
other unusual effects which may indicate need to discontinue therapy.
- Do not consume foods and beverages containing tyramine or tryptophan or drugs containing pressor agent. These can cause
severe hypertensive reactions. Get a list from your care provider.
- Avoid drinking excessive caffeine and chocolate beverages (e.g., coffee, tea, cocoa, or cola).
- Discuss with physician wearing elastic stockings and elevating legs when sitting to minimize hypotensive effects of drug.
- Make position changes slowly, especially from recumbent to upright posture, and dangle legs over bed a few minutes before
rising to walk. Avoid standing still for prolonged periods. Also avoid hot showers and baths (resulting vasodilatation may
potentiate hypotension); lie down immediately if feeling light-headed or faint.
- Check weight 2 or 3 times per wk and report unusual gain.
- Report jaundice. Hepatotoxicity is believed to be a hypersensitivity reaction unrelated to dosage or duration of therapy.
- Avoid overexertion while taking this drug. MAO inhibitors may suppress anginal pain that would otherwise serve as a warning
sign of myocardial ischemia.