Factors affecting the delay of antidepressant effect in responders to nortriptyline and phenelzine

Seventy-six elderly depressed patients who had responded to either nortriptyline or phenelzine after a trial of up to 3 months were examined. The mean week of response was nearly 6 weeks. Patients who were more severely depressed took longer to respond. Patients with endogenous depression responded sooner on nortriptyline than did patients with nonendogenous depression. For patients on nortriptyline, lower plasma levels in the early weeks of treatment may delay response while differences in platelet monoamine oxidase inhibition in the early weeks of treatment do not appear to affect week of response for patients on phenelzine.