Fifty depressed in-patients at two psychiatric units, one in Italy the other in England, were treated with clomipramine, either orally, or intravenously and orally. A comparison of clinical response with plasma levels of clomipramine and its metabolite, desmethylclomipramine, showed clear relationships especially in the case of desmethylclomipramine. In the intravenously-treated group this was linear, in the orally-treated group it was curvilinear. Plasma levels of desmethylclomipramine and administered clomipramine correlate highly.
These findings, together with the fact that significant clinical improvement was observed in only 55 per cent of the patients, suggest that titration of the administered dose to obtain more effective plasma levels of the metabolite might improve the clinical response to the drug in some patients.