Transformation and Excretion of Drugs in Biological Systems. XI. Renal Excretion Mechanisms of Sulfonamides in Rabbits. (3)

Abstract

In order to clarify the renal tubular reabsorption of sulfonamides, the effects of urinary pH and urine flow rate on the renal excretion of four sulfonamides were examined in rabbits. The excretion ratio (ER) of sulfanilamide, sulfamethoxypyridazine and sulfamethizole were little or not affected by modification of the urinary pH, but that of sulfisoxazole was considerably influenced. It was also demonstrated that the ER of these sulfonamides except for sulfamethizole increased with increasing urine flow rate. Only sulfamethizole exhibited as the excretion pattern which was dependent on its plasma level. These different responses to the influencing factors may be described on the basis of their secretion characteristics, reabsorption by non-ionic diffusion and their lipoid solubility. © 1975, The Pharmaceutical Society of Japan. All rights reserved.