Formation of the sulfone metabolite of didesmethylchlorpromazine in the rat in vivo and in vitro.

In peripheral tissues of male rats given 25 mg of didesmethylchlorpromazine [gamma-(2-chlorophenothiazinyl-10)-propylamine, Cl-PPA] per kg ip, high levels of the corresponding sulfoxide (Cl-PPA-SO) and the sulfone (Cl-PPA-SO2) were measured during the following 2-24 hr. Small quantities of these metabolites were excreted in bile, whereas 7-hydroxy-Cl-PPA could not be detected. By comparison of the areas under the tissue concentration-time curves with those measured after injection of Cl-PPA-SO2, it could be shown that at least 50% of the Cl-PPA dose was converted to the sulfone. Following administration of Cl-PPA-SO, the sulfone was present in tissues and in urine. An NADPH-dependent oxygenase catalyzing the conversion of Cl-PPA-SO to Cl-PPA-SO2 was localized in liver microsomes. Attempts to characterize the enzyme by means of induction and inhbition experiments did not lead to unequivocal conclusions concerning its nature.