The aim of this study was to explore the possible relationship between plasma clomipramine (CMI) and its major metabolite (DMCMI) levels and related parameters, and clinical features in OCD patients.

Twenty-six OCD outpatients (13 men, 13 women), suffering from OCD were consecutively enrolled in the study. The severity of OCD was assessed by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). The measurements were carried out after four weeks and six months from the beginning of the treatment.

The drug levels were measured by a HPLC method developed by us. The correlations between biological and clinical parameters were analyzed by means of the Spearman's correlation coefficient. The Mann-Whitney test was used for comparing biological and clinical variables between men and women.

The results showed that CMI levels were related to the doses at the two assessment times. A significant and positive correlation was detected at the beginning between the DMCMI/ratio and the Y-BOCS total score, however this was true only for men, where the similar correlations were measured also with the Y-BOCS subscale. After six months of CMI, men showed a significant improvement of the compulsions.

These findings would highlight the potential impact of assessing CMI plasma levels and their relationships with specific symptoms, as well as the influence of the gender on the drug response.