Imipramine in adolescent major depression: plasma level and clinical response

Thirty-four adolescents with mean age 14.25 years who met RDC criteria for major depressive disorder as assessed with the K-SADS, were treated for 6 weeks on a fixed schedule of imipramine hydrochloride titrated to a dosage of 5.0 mg/kg/day except as limited by side effects. Mean dose was 246 mg/day (4.5 mg/kg/day). In spite of good indications of compliance with treatment only 44% of the adolescents improved to the level of no or only slight depressed mood or anhedonia, though most had less depressive symptomatology at the end of treatment. There was neither a linear nor curvilinear relationship between total plasma level of IMI plus DMI and clinical response, despite a wide range of both plasma level (77 ng/ml to 986 ng/ml) and outcome. Adolescents with associated separation anxiety had significantly poorer response to treatment of their depressive disorder than those with major depression alone. Poor response was also weakly associated with being female, having endogenous subtype of depression, and having higher plasma IMI (but not DMI) level. In the context of similar studies of IMI on depression in other age groups, it is hypothesized that high levels of sex hormones during adolescence and young adulthood may interfere with IMI's antidepressant effects. It is concluded that other types of antidepressants should be tested in adolescents with major depression.