Protriptyline plasma levels and antidepressant response

Abstract

Twenty-one depressed outpatients were treated for 4 wk with 20 mg Iday of protriptyline. Protriptyline plasma levels in individuals after 4 wk ranged from 22 nglml to 167 nglml. There was a negative correlation (-0.50, p < 0.05) between the severity of depression measured by the Hamilton Rating Scale (HRS) and the wk 4 protriptyline concentration. Patients with plasma levels above 70 ng Iml (wk 4) had better outcomes measured by the HRS (p < 0.05) and the Zung Self-Rating Depression Scale (p < 0.05) and had greater percent decreases on both scales (p < 0.05) during treatment than those with lower plasma levels. An upper limit to the therapeutic plasma level range beyond which response to treatment was less satisfactory was not demonstrated in this study.