Abstract
Rate constants of acetylation, k1, and excretion, k3, for 14 sulfonamides have been studied using pure strain rats. The results were compared with those of rabbits. Values of k3 in rats were closely related with partition coefficients at pH same as of urine. Excretion of sulfonamides was markedly influenced by urinary pH. The urinary pH of rats was modified to 8.6±0.2 by the administration of NaHCO3. Then, a rate constant for excretion was twice increased. The results suggest that sulfonamides are reabsorbed from the renal tubule in the form of unionized molecules in the filtrate.
