Relationship between parameters of serotonin transport and antidepressant plasma levels or therapeutic response in depressive patients treated with paroxetine and amitriptyline

Abstract

In a double‐blind clinical study, antidepressant plasma levels, parameters of platelet serotonin (5‐HT) transport (K m , V max and basal platelet 5‐HT content) and therapeutic response were measured in depressive patients treated with either paroxetine (30 mg/day) or amitriptyline (150 mg/day) for 6 weeks. No correlation could be found between paroxetine plasma levels and therapeutic outcome after 2, 4 and 6 weeks of treatment. In contrast to the amitriptyline group, a marked increase in K m from baseline to week 2 was determined in paroxetine‐treated patients, with K m increase being correlated with paroxetine plasma levels at week 2. However, no significant relationship could be found between 5‐HT transport parameters and any of the outcome measures in either treatment group.