Paroxetine and imipramine treatment of depressive patients in a controlled multicentre study with plasma amino acid measurements.

In a 12-week double-blind study with 36 patients with major depressive episode (DSM-III), paroxetine (Seroxat, Aropax) showed significantly quicker onset of efficacy on the Melancholia Scale, and better tolerance than imipramine. Plasma concentration analyses showed no clear concentration-efficacy correlation in either treatment group. During long-term treatment paroxetine seemed to be superior to imipramine in preventing relapse; both treatments were well tolerated. A significant correlation between baseline plasma tryptophan: large neutral amino acids ratio and final Hamilton Rating Scale for Depression (HRSD) score and a trend towards an inverse correlation between this ratio and percentage reduction in HRSD score were seen in the paroxetine group but not in the imipramine group. In line with previous studies, these results support the hypothesis that paroxetine is an effective and well tolerated antidepressant.