Phenolic metabolites of thioridazine in man.

After oral administration of thioridazine or mesoridazine to man, faecal extracts contained mainly unconjugated 7-hydroxy-thioridazine and its demethylated analogue, together with some 3-hydroxy-thioridazine, and 7-hydroxy derivatives of sulphoridazine and desmethyl sulphoridazine. In contrast, urine contained free 7-hydroxy-mesoridazine, and no free 7-hydroxy-thioridazine was detectable. Conjugates of all these phenols were also found. After oral sulphoridazine administration (thioridazine side-chain sulphone), urine contained mainly 7-hydroxy-sulphoridazine and faeces both 7-hydroxy-sulphoridazine and its desmethyl analogue. Sulphoridazine metabolism is therefore much simpler than that of thioridazine. This different elimination pattern in faeces and urine may be due to reduction of sulphoxides but not sulphones by intestinal bacteria.