The effect of nitrite on 14C-sulphathiazole (4-amino-N-2-thiazolyl[U-14C]benzenesulphonamide) metabolism in the rat

1. Rats given a meal containing 613 p.p.m. of 14C-sulphathiazole (4-amino-N-2-thiazolyl[14C]benzenesulphonamide) excreted less 14C-activity in urine and more 14C-activity in faeces as nitrite in the meal was increased (0, 10, 100 or 1000 p.p.m.). As nitrite in the meal was increased from 0 to 1000 p.p.m. the total 14C-residues in the gastrointestinal tract six hours after dosing increased, but decreased in other tissues. 2. High nitrite in the meal resulted in increased methanol insoluble 14C-activity in the gastrointestinal tract but had little or no effect on the methanol-insoluble activity in liver and blood. 3. Conversion of 14C-sulphathiazole to 14C-desaminosulphathiazole (N-2-thiazolyl[U-14C]benzenesulphonamide) in the rat was greatly increased by nitrite in the meal.