Effects of probenecid on plasma/tissue distribution of 14C-benzylpenicillin in rats.

Probenecid (50 mg . kg-1) was found to induce an increase of the plasma concentration of 14C-benzylpenicillin with a decrease of the concentration in liver and kidney. Accumulation in corresponding tissue slices was reduced by probenecid. Therefore, the well known increase of penicillin in plasma after probenecid seems to be not only due to an inhibition of renal excretion but also to a reduced tissue uptake in liver and kidney.