New Concept of Competitive Inhibition of the Renal Tubular Excretion of Penicillin.

It has been found that the excretion of penicillin by a renal tubular transport mechanism could be physiologically inhibited reversibly. The basis for this effect is thought to be one of substrate competition between penicillin, which is excreted by the tubules, and 4'-carboxyphenyl-methanesulfonanilide, which is essentially refractory to excretion by that transport mechanism.