Factors affecting the absorption and biliary excretion of erythromycin and two of its derivatives in humans

Abstract

The oral administration of the propionyl ester of erythromycin and the lauryl sulfate salt of the ester produces higher serum concentrations than the parent antibiotic, erythromycin. Lee explained this by his findings in rats that the biliary excretion of erythromycin was relatively high while that of the two derivatives was low. We extended his work to humans. In 16 patients, with bile fistula propionyl erythromycin administered orally was followed by relatively high serum and low bile antibiotic activity, as compared to erythromycin. The lauryl sulfate salt form followed a pattern similar to the ester. Diverting antibiotic‐containing bile from the intestine lowered the serum antibiotic concentration during treatment with erythromycin. However, this procedure had little effect on the two derivatives, since they appear in the bile in only a minimal amount. The clinical findings support the animal data.