Biochemical correlates of antidepressant response. Results of a trazodone versus amitriptyline trial.

Changes in the uptake of 3H-serotonin into platelets, serotonin receptor activity on platelets, and plasma free and bound tryptophan concentrations were determined in a group of 54 moderately to severely depressed patients (mean Hamilton Rating Scale 17) before and during treatment with either trazodone or amitriptyline. No difference was found between the free and bound tryptophan concentrations of the depressed patients or their controls nor was any change detected during drug treatment. Platelet serotonin receptor activity and uptake were significantly lower in the depressed patients than in the controls and in those patients which subsequently responded to drug treatment. There was no apparent correlation between the ability of trazodone to inhibit the uptake of serotonin into the platelets and the antidepressant response; all patients responding to drug treatment showed an enhanced serotonin uptake. There is evidence from this study that changes in serotonin receptor function and uptake into platelets may correlate with the clinical status of depressed patients.