tranylcypromine

Tranylcypromine is a monoamine oxidase inhibitor (MAOI) used as an antidepressant. It is non-selective and irreversible, typically marketed under brand names such as Parnate. It is generally reserved for treatment of major depressive disorder that has not responded to other therapies.

The drug acts by inhibiting monoamine oxidase enzymes, MAO-A and MAO-B, in the brain and gut. This leads to increased levels of monoamines including serotonin, norepinephrine, and dopamine, which can improve mood. Because MAO in the gut is also inhibited, ingestion of tyramine-rich foods can cause dangerous hypertensive reactions, a key consideration in dietary management with tranylcypromine.

Indications for tranylcypromine include treatment of major depressive disorder, particularly in cases that are resistant to other antidepressants or show atypical features. It is generally not a first-line agent due to dietary restrictions, potential drug interactions, and safety concerns. It requires careful patient selection, counseling on diet, and monitoring for adverse effects and interactions.

Pharmacokinetics and duration: tranylcypromine is administered orally and is rapidly absorbed. It is metabolized in the liver and, as an irreversible MAOI, its pharmacologic effect lasts until new MAO enzymes are synthesized, which can prolong its action beyond the presence of the drug itself. Onset of antidepressant effects typically takes several weeks.

Safety and interactions: a major safety issue is the risk of hypertensive crisis with ingestion of tyramine-containing foods. It carries significant interactions with serotonergic drugs (risk of serotonin syndrome), sympathomimetics, and certain analgesics; careful washout periods are required when switching from other antidepressants. Contraindications include uncontrolled hypertension, cardiovascular disease, pheochromocytoma, and significant hepatic impairment. Patients should be educated on diet, potential side effects, and when to seek medical attention. Common adverse effects include insomnia, anxiety, dizziness, orthostatic hypotension, and sexual dysfunction.