SERUM CONCENTRATIONS OF AMPICILLIN IN NEWBORN INFANTS AFTER ORAL ADMINISTRATION

Previous studies have shown that antimicrobial agents as well as other agents differ in their absorption, metabolism, and excretion in the newborn compared to older children and adults. Earlier work with the natural penicillin, penicillin G, and the monobasic semisynthetic penicillin, nafcillin, showed that the administration of these products in newborn infants resulted in a significantly altered serum level time curve compared to that obtained after administration to adults. The present study shows that this same relationship holds for the amphoteric penicillin, ampicillin. The differences noted between the infants and adults are probably due to a difference in the excretory ability of the neonatal kidney compared to the more mature kidney. In addition, it was shown that the newborn was similar to the adult in utilizing more efficiently the more soluble anhydrous ampicillin, as compared with the trihydrate.