Hydroxylated metabolites of antidepressants

Hydroxylated metabolites (OHMs) of antidepressant drugs are pharmacologically active. On chronic administration, unconjugated OHM plasma concentrations can be substantial compared to that of the parent compound, especially for secondary amine TCAs and bupropion. OHMs may contribute to toxicity and may contribute to, or attenuate, efficacy. Direct administration of OHMs may be associated with antidepressant effects.