No difference in adherence to paroxetine between depressed patients with early remission and those with late remission based on monitoring of plasma paroxetine concentrations

Abstract

Selective serotonin reuptake inhibitors (SSRIs) are widely used to treat both anxiety disorders and depressive disorders. However, nonadherence to SSRIs is a major issue in recurrence. In the present study, we investigated paroxetine adherence in depressed patients by monitoring the plasma paroxetine concentrations between patients with rapid and those with a late response to paroxetine treatment. Twenty inpatients in our university hospital, who met the DSM-IV-TR diagnosis of major depressive disorder in a single episode, were enrolled in the study. Twelve patients (M/F: 7/13, age: 37.4 +/- 10.4 years) were treated with paroxetine (40 mg/day), and all achieved remission (HAMD < or = 7) within at least 12 weeks. We divided the patients into two groups, an early-remission group (HAMD < or = 7 within 4 weeks) and a late-remission group (HAMD < or = 7 within 8-12 weeks). Their dosages of paroxetine were constant because of no emerging adverse effects. Blood samples were obtained on the day the subjects were discharged (B) and 12 weeks after discharge. The paroxetine concentrations in the early-remission group were significantly decreased 12 weeks after discharge, and no difference was found between the early- and late-remission groups. These results suggest that adherence to paroxetine was independent of the duration of the depressive state suffered by the patients. Clinicians always take their cautions for the adherence to paroxetine regardless of the clinical time courses the patients recovering from their depressive symptoms.