The metabolism of thionicotinamide in the rat

The metabolism of the thioamide, thionicotinamide, in the male Wistar rat is described. Thionicotinamide was shown to be metabolised to inorganic sulphate, thionicotinamide S-oxide and also N1-methylnicotinamide, which arises from N-methylation of nicotinamide via desulphuration of the parent thioamide. At 24 hours from dosing about 35% of the dose had been excreted as inorganic sulphate and 20.5% as the S-oxide metabolite. Three metabolites, detected by their fluorescence under UV light, have not been positively identified but are postulated to be pyridones, resulting from ring oxidation, by analogy with other thioamides. S-Oxidation is an important metabolic pathway as it may give rise to toxic intermediates.