An evaluation of two doses of isocarboxazid in depression

Two fixed doses of isocarboxazid were studied over a 4-week period in depressed in-patients. Thirty-five patients completed treatment, 20 of whom received 30 mg isocarboxazid per day, and 15 of whom received 50 mg isocarboxazid per day. No overall difference between the two doses was observed. When patients were subdivided into melancholia/endogenous depression or non-melancholia/non-endogenous depression, the higher dose exerted significantly greater antidepressant effects in the latter groups. Diagnostic type is considered to be an important variable in studies of dose-effect relationships with antidepressant drugs. The side effects of isocarboxazid at the two doses studied did not differ materially, although there was a suggestion of greater anticholinergic effect at 50 mg.