Clinical Implications of Imipramine Plasma Levels for Depressive Illness

There was a statistically and clinically significant relationship between plasma levels and response and this relationship existed across the entire sample, and was accentuated when the bipolar and unipolar nondelusional populations were examined.

Abstract

Sixty depressed nonschizophrenic patients were admitted to a research unit. Following one drug-free week and one week of placebo, patients received 3.5 mg/kg of imipramine hydrochloride for 28 days. Plasma levels of imipramine and its metabolite desipramine hydrochloride (desmethylimipramine) were measured three times weekly and the relationship between plasma steady-state levels and clinical outcome was examined. Steady-state levels ranged from 50 to 1,050 ng/ml. There was a statistically and clinically significant relationship between plasma levels and response. The relationship existed across the entire sample, and was accentuated when the bipolar and unipolar nondelusional populations were examined. Because a strong relationship between sex and outcome was observed, the unipolar nondelusional patients were stratified by sex and a significant relationship still persisted. Only the unipolar delusional patients failed to demonstrate an association between blood level and clinical response.