Relationship between tricyclic antidepressant plasma levels and clinical response in patients treated with desipramine or doxepin

A study examining the relationship between plasma levels of tricyclic antidepressants (TCA), clinical response, and side effects was performed in patients with major affective disorder. Patients received either desmethylimipramine (DMI) (150-200 mg/day) or doxepin (200 mg/day) for 4 weeks. No significant correlations were found between plasma levels and either clinical response or side effects when males and females were analyzed together. A significant correlation between plasma levels and response was found in females taking desmethylimipramine. Support for the finding that females may show a stronger relationship than males between clinical response and plasma TCA levels is provided from analysis of previous studies in the literature.