Nurses Compass
Drug Guide
Phenelzine Sulfate
Classification
Therapeutic: Antidepressant, Monoamine Oxidase Inhibitor (MAOI)
Pharmacological: Irreversible monoamine oxidase inhibitor
FDA Approved Indications
- Major depressive disorder, typically when other antidepressants have failed
Mechanism of Action
Phenelzine irreversibly inhibits monoamine oxidase enzymes (MAO-A and MAO-B), leading to increased levels of monoamine neurotransmitters (serotonin, norepinephrine, dopamine) in the central nervous system, which helps alleviate depressive symptoms.
Dosage and Administration
Adult: Initially 30 mg/day in divided doses, titrated up to 60-90 mg/day as needed, in divided doses
Pediatric: Not approved for pediatric use
Geriatric: Start at lower doses with cautious titration due to increased sensitivity and potential interactions
Renal Impairment: Use with caution; dose adjustments not well established
Hepatic Impairment: Start at lower doses and monitor closely
Pharmacokinetics
Absorption: Well absorbed orally
Distribution: Widely distributed in body tissues including the brain
Metabolism: Biotransformed in the liver, with active metabolites
Excretion: Renal excretion of metabolites
Half Life: Approximately 11 hours; irreversible enzyme inhibition means effect lasts longer than the drug’s presence in plasma
Contraindications
- Concurrent use with other serotonergic or sympathomimetic drugs
- History of hypersensitivity to phenelzine or other MAOIs
- Acute cerebrovascular accident
Precautions
- Risk of hypertensive crisis with tyramine-rich foods or certain medications; contraindicated in patients with hepatic impairment, severe cardiovascular disease, or psychiatric conditions prone to agitation or psychosis
Adverse Reactions - Common
- Dizziness, headache, dry mouth (Common)
- Sedation or insomnia (Common)
- Weight gain (Common)
Adverse Reactions - Serious
- Hypertensive crisis (due to tyramine or other vasoactive substances) (Serious)
- Serotonin syndrome (when combined with other serotonergic agents) (Serious)
- Orthostatic hypotension (Serious)
- Liver toxicity (rare) (Rare)
Drug-Drug Interactions
- SSRIs, SNRIs, tryptophan, other antidepressants (risk of serotonin syndrome)
- Sympathomimetic agents (e.g., pseudoephedrine)
Drug-Food Interactions
- Tyramine-rich foods (aged cheese, cured meats, fermented foods) leading to hypertensive crisis
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor blood pressure regularly, hepatic function, and mental status; assess for symptoms of serotonin syndrome or hypertensive crisis.
Diagnoses:
- Risk for hypertensive crisis
- Risk for serotonin syndrome
Implementation: Educate patient on dietary restrictions, medication adherence, and recognizing adverse effects.
Evaluation: Assess for stabilization of depressive symptoms, blood pressure control, and absence of adverse effects.
Patient/Family Teaching
- Avoid tyramine-rich foods and certain medications (e.g., certain decongestants, other antidepressants) during therapy.
- Report symptoms of hypertensive crisis (severe headache, neck stiffness, rapid heartbeat) immediately.
- Adhere strictly to medication dosing schedule and dietary restrictions.
Special Considerations
Black Box Warnings:
- Serious, sometimes fatal, interactions with other serotonergic drugs or foods leading to hypertensive crisis or serotonin syndrome
Genetic Factors: Genetic variability in monoamine oxidase activity may influence response and side effects.
Lab Test Interference: Possible interference with liver function tests.
Overdose Management
Signs/Symptoms: Severe hypertension, hyperthermia, seizures, altered mental status
Treatment: Supportive care; manage hypertensive crisis with appropriate antihypertensives; activated charcoal if recent ingestion; avoid sympathomimetic drugs.
Storage and Handling
Storage: Store at room temperature away from moisture, heat, and light
Stability: Stable under proper storage conditions for the duration of the labeled expiry date.