Category: drug_metabolism
Outer mitochondrial membrane flavoenzymes — degrade biogenic amines via oxidative deamination → aldehyde intermediates → carboxylic acids (via ALDH). MAO-A: serotonin, norepinephrine, dopamine (high affinity) — broad tissue distribution. MAO-B: dopamine, phenethylamine, benzylamine — concentrated in CNS + platelets. Pharmacology: irreversible non-selective inhibitors (phenelzine, tranylcypromine, isocarboxazid) — antidepressants with the famous tyramine hypertensive-crisis risk (dietary tyramine bypasses MAO-A in the gut + reaches systemic circulation, releases stored norepinephrine). Selective + reversible MAO-A: moclobemide (less tyramine risk). Selective MAO-B: SELEGILINE (Parkinson disease adjunct + transdermal for depression; reversible loss-of-selectivity at high doses), RASAGILINE (newer; once-daily). Selegiline metabolizes to amphetamine + methamphetamine — explains some of its CNS effects.