Effect of Isoxazolyl-penicillin on the Rectal Absorption of Ampicillin in Rabbits and Humans

Abstract

The effects of isoxazolyl-penicillins on the rectal absorption of ampicillin were investigated in rabbits and humans. The bioavailability of ampicillin following administration of a suppository in the presence or absence of an isoxazolyl-penicillin was determined from the blood level in rabbits and from the urinary excretion (0-6 h) in humans. Rectal absorption of ampicillin from the suppository was enhanced by the presence of an isoxazolyl-penicillin in both rabbits and humans, though the effect was much greater in rabbits than in humans. The absorption-promoting effects of isoxazolyl-penicillins appeared to be related to their partition coefficients between n-octanol and buffer solution (pH 7.4).