MAO-A inhibitor
Monoamine oxidase A inhibitor
- Serotonin, norepinephrine and tyramine persist
- If BBB-crossing: antidepressant effect
- Tyramine accumulation → hypertensive crisis (the cheese reaction)
- Serotonin toxicity risk mandates washout from serotonergic drugs
- Serotonicity — how much a drug raises synaptic serotonin; distinction from “serotonergic”
Drugs with this mechanism (13)
- Isocarboxazid — Rarely used irreversible MAOI.
- Isoniazid — First-line tuberculosis drug; hepatotoxicity and pyridoxine-responsive neuropathy shape use.
- Linezolid — Oxazolidinone antibiotic for resistant gram-positives; a reversible MAOI (serotonin risk).
- Methylene blue — Methemoglobinemia antidote and reversible MAOI; serotonergic combinations can be dangerous.
- Moclobemide — Reversible MAO-A inhibitor (RIMA); safer tyramine profile; not marketed in the US.
- Phenelzine — Irreversible, nonselective MAOI for atypical or resistant depression; tyramine restrictions apply.
- Procarbazine — DNA-damaging chemotherapy used in lymphoma and brain-tumor regimens; weak MAO inhibition adds food and drug interaction concerns.
- Rasagiline — Selective MAO-B inhibitor for Parkinson; no tyramine diet at usual dose.
- Safinamide — Reversible MAO-B inhibitor; levodopa adjunct for wearing-off; can worsen dyskinesia.
- Selegiline — MAO-B-selective at low dose; the transdermal patch treats depression without diet at low strength.
- Selegiline transdermal — MAOI antidepressant patch; the 6 mg/24 h dose needs no tyramine diet, sparing gut MAO-A.
- Tedizolid — Once-daily oxazolidinone for acute bacterial skin infections, including MRSA; inhibits 50S protein synthesis.
- Tranylcypromine — Activating, amphetamine-like MAOI; dietary restrictions apply.
Self-check
- Why can tyramine cause a hypertensive crisis during MAO-A inhibition?
Tyramine accumulates. - What is required for MAO-A inhibition to produce an antidepressant effect?
BBB penetration.
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