Imipramine binding as a predictor of fluoxetine response in depressed patients.

We evaluated platelet 3H-imipramine (3H-IMI) binding parameters (Bmax and Kd) at baseline (t0) and 2 months after (t1) treatment with fluoxetine in a group of outpatients affected by a major depressive episode, according to DSM-IIIR criteria. The possible relationships between biological parameters and the Hamilton Rating Scale for Depression (HRSD) total score were examined. The results confirmed previous reports that depressed patients possessed a lower density (Bmax) of platelet 3H-IMI binding sites than healthy controls, but the Bmax tended to decrease with fluoxetine. In addition, we observed a negative correlation between Bmax values at t0 and the HRSD total scores at t1 indicating that the patients who responded better to fluoxetine were those with a lower Bmax at t0. Future studies will substantiate this preliminary observation on the possible usefulness of platelet 3H-IMI binding as a predictor of pharmacological response.