Phenelzine

General information

Indicated for: Treatment-resistant depression; atypical depression.

Dosing & forms

• Forms/strengths: —
• Frequency: —
• Food: —
• Typical range: 45–90 mg/day (divided)

Mechanism (brief)

Irreversible nonselective MAO inhibitor increasing serotonin, norepinephrine, and dopamine.

Metabolism & Half‑life

• Metabolism: Acetylation (NAT2) and CYP1A2.
• Half‑life: ~12 h (pharmacodynamic effect 7–14 days).

Therapeutic Drug Monitoring (TDM)

Recommended: No

Monitoring highlights

• Blood pressure (monitor for orthostatic hypotension and hypertensive crisis) — Baseline and each visit
• Dietary counseling on tyramine restriction — Baseline and reinforcement

Sources

• Phenelzine label — DailyMed (2025)