PHENELZINE SULFATE

( fen' el zeen)
Nardil
PREGNANCY CATEGORY C

Drug classes
Therapeutic actions
Indications
Contraindications and cautions
Available forms
Dosages
  Adults
  Pediatric patients
  Geriatric patients
Pharmacokinetics
Adverse effects
Interactions
  Drug-drug
  Drug food
  Drug-alternative therapy
Nursing considerations Assessment
Interventions
Teaching points

 

Drug classes

Antidepressant
Monoamine oxidase inhibitor (MAO inhibitor)

Therapeutic actions

Irreversibly inhibits MAO, an enzyme that breaks down biogenic amines, such as epinephrine, norepinephrine, and serotonin, thus allowing these biogenic amines to accumulate in neuronal storage sites. According to the biogenic amine hypothesis, this accumulation of amines is responsible for the clinical efficacy of MAOIs as antidepressants.

Indications

• Treatment of patients with depression characterized as atypical, nonendogenous, or neurotic; patients who are unresponsive to other antidepressive therapy; and patients in whom other antidepressive therapy is contraindicated

Contraindications and cautions

• Contraindicated with hypersensitivity to any MAOI, pheochromocytoma, CHF, history of liver disease or abnormal liver function tests, severe renal impairment, confirmed or suspected cerebrovascular defect, CV disease, hypertension, history of headache, myelography within previous 24 hr or scheduled within 48 hr.
• Use cautiously with seizure disorders; hyperthyroidism; impaired Hepatic; renal function; psychiatric patients (agitated or schizophrenic patients may show excessive stimulation; manic-depressive patients may shift to hypomanic or manic phase); patients scheduled for elective surgery; pregnancy; lactation.

Available forms

Tablets—15 mg

Dosages

Adults

Initially, 15 mg PO tid. Increase dosage to at least 60 mg/day at a fairly rapid pace consistent with patient tolerance. Many patients require therapy at 60 mg/day for at least 4 wk before response. Some patients may require 90 mg/day. After maximum benefit is achieved, reduce dosage slowly over several weeks. Maintenance may be 15 mg/day or every other day.

Pediatric patients

Not recommended for patients < 16 yr.

Geriatric patients

Patients > 60 yr are more prone to develop adverse effects; adjust dosage accordingly.

Pharmacokinetics


Route Onset Duration
Oral Slow 48–96 hr

Metabolism: Hepatic; T ½: unknown

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

Adverse effects in Italics are most common; those in Bold are life-threatening.

•  CNS: Dizziness, vertigo, headache, overactivity, hyperreflexia, tremors, muscle twitching, mania, hypomania, jitteriness, confusion, memory impairment, insomnia, weakness, fatigue, drowsiness, restlessness, overstimulation, increased anxiety, agitation, blurred vision, sweating, akathisia, ataxia, coma, euphoria, neuritis, repetitious babbling, chills, glaucoma, nystagmus
•  CV: Hypertensive crises (sometimes fatal, sometimes with intracranial bleeding, usually attributable to ingestion of contraindicated food or drink containing tyramine; see drug-food interactions below; symptoms include some or all of the following: occipital headache, which may radiate frontally; palpitations; neck stiffness or soreness; nausea; vomiting; sweating; dilated pupils; photophobia; tachycardia or bradycardia; chest pain); orthostatic hypotension, sometimes associated with falling; disturbed cardiac rate and rhythm, palpitations, tachycardia
•  Dermatologic: Minor skin reactions, spider telangiectases, photosensitivity
•  GI: Constipation, diarrhea, nausea, abdominal pain, edema, dry mouth, anorexia, weight changes
•  GU: Dysuria, incontinence, urinary retention, sexual disturbances
•  Other: Hematologic changes, black tongue, hypernatremia

Interactions

Drug-drug

• Increased sympathomimetic effects (hypertensive crisis) with sympathomimetic drugs (norepinephrine, epinephrine, dopamine, dobutamine, levodopa, ephedrine), amphetamines, other anorexiants, local anesthetic solutions containing sympathomimetics
• Hypertensive crisis, coma, severe convulsions with TCAs (eg, imipramine, desipramine). Note: MAOIs and TCAs have been used successfully in some patients resistant to therapy with single agents; however, case reports indicate that the combination can cause serious and potentially fatal adverse effects.
• Additive hypoglycemic effect with insulin, oral sulfonylureas
• Increased risk of adverse interaction with meperidine
• Risk of serotonin syndrome if combined with SSRIs

Drug food

• Tyramine (and other pressor amines) contained in foods are normally broken down by MAO enzymes in the GI tract; in the presence of MAOIs, these vasopressors may be absorbed in high concentrations; in addition, tyramine releases accumulated norepinephrine from nerve terminals; thus, hypertensive crisis may occur when the following foods that contain tyramine or other vasopressors are ingested by a patient on an MAOI: dairy products (blue, camembert, cheddar, mozzarella, parmesan, romano, roquefort, Stilton cheeses; sour cream; yogurt); meats, fish (liver, pickled herring, fermented sausages—bologna, pepperoni, salami; caviar; dried fish; other fermented or spoiled meat or fish); undistilled beverages (imported beer, ale; red wine, especially Chianti; sherry; coffee, tea, colas containing caffeine; chocolate drinks); fruit/vegetables (avocado, fava beans, figs, raisins, bananas); yeast extracts, soy sauce, chocolate

Drug-alternative therapy

• May cause headaches, manic episodes if combined with ginseng therapy

Nursing considerations Assessment

•  History: Hypersensitivity to any MAOI; pheochromocytoma, CHF; abnormal liver function tests; severe renal impairment; cerebrovascular defect; CV disease, hypertension; history of headache; myelography within previous 24 hr or scheduled within 48 hr; seizure disorders; hyperthyroidism; impaired hepatic, renal function; psychiatric patients; elective surgery; pregnancy, lactation
•  Physical: Weight; T; skin color, lesions; orientation, affect, reflexes, vision; P, BP, orthostatic BP, auscultation, perfusion; bowel sounds, normal output, liver evaluation; urine flow, normal output; thyroid palpation; liver, kidney, and thyroid function tests, urinalysis, CBC, ECG, EEG

Interventions

• Limit amount of drug that is available to suicidal patients.
• Monitor BP and orthostatic BP carefully; arrange for more gradual increase in dosage in patients who show tendency for hypotension.
• Have periodic liver function tests during therapy; discontine drug at first sign of hepatic dysfunction or jaundice.
• Discontinue drug and monitor BP carefully if patient reports unusual or severe headache.
• Provide phentolamine or another alpha-adrenergic blocking drug on standby in case hypertensive crisis occurs.
• Provide diet that is low in tyramine-containing foods.

Teaching points

• Take drug exactly as prescribed. Do not stop taking this drug abruptly or without consulting your health care provider.
• Avoid ingestion of tyramine-containing foods while you are taking this drug and for 2 wk afterward (patient and significant other should receive a list of such foods).
• Avoid alcohol; other sleep-inducing drugs; all OTC drugs, including nose drops, cold and hay fever remedies; and appetite suppressants. Many of these contain substances that could cause serious or even life-threatening problems.
• These side effects may occur: dizziness, weakness or fainting when arising from a horizontal or sitting position (transient; change position slowly); drowsiness, blurred vision (reversible; if severe, avoid driving or performing tasks that require alertness); nausea, vomiting, loss of appetite (small, frequent meals, frequent mouth care may help); memory changes, irritability, emotional changes, nervousness (reversible).
• Report headache, rash, darkening of the urine, pale stools, yellowing of the eyes or skin, fever, chills, sore throat, any other unusual symptoms.


Copyright © 2004 Lippincott Williams & Wilkins
Amy M. Karch
2004 Lippincott's Nursing Drug Guide