Determination of the acetylator phenotype and pharmacokinetics of some sulphonamides in man.

The pharmacokinetics of sulphamethizole, sulphamethoxazole, sulphadiazine, sulphapyridine and sulphadimidine have been studied in man. Renal clearance values of the metabolite N4-acetylsulphonamide are 6 to 20 times higher than those of the corresponding parent compound. The renal clearance of sulphonamides is dependent on the urine flow. N4-Acetylsulphonamide concentration-time profiles for plasma and urine have been constructed for the sulphonamides. The percentage N4-acetylsulphonamide-time profiles for plasma are excellent tools for establishing the acetylator phenotype, while those constructed from urine samples are less useful. Evidence is obtained that sulphadimidine is metabolically processes by 2 different isoenzymes, while sulphadiazine, sulphapyridine and sulphamethoxazole are processes by 1 acetylating isoenzyme. Sulphamethizole is acetylated to very little extent.