Absorption of amino penicillins from everted rat intestine.

Abstract

Using an in vitro everted gut sac method based on that of Wilson and Wiseman, a number of amino penicillins were tested to identify the involvement of any specialized transport mechanisms in their absorption across rat intestine. Only 1 of the amino penicillins, cyclacillin (1-amino-cyclohexyl penicillin) was actively transported. The other penicillins appeared to diffuse passively across the intestine. Cyclacillin concentrated against a gradient at 37.degree. C but not at 19.degree. C. Transport of cyclacillin across the mucosal membrane was saturated at mucosal concentrations > 1000 .mu.g/ml. The rate of the forward flux of cyclacillin was many times that of its back flux. No relationship between the active transport of cyclacillin and that of amino acids could be demonstrated.