Pharmacologic evaluation of orally administered antibiotics in infants and children: effect of feeding on bioavailability.

The clinical pharmacology of orally administered antibiotics was investigated in 106 infants and children. The antibiotic suspensions studied were ampicillin, cephalexin, erythromycin estolate, erythromycin ethylsuccinate, penicillin G, and penicillin V. The feeding status of the patients was evaluated in relation to the concentrations of drugs in serum, saliva, and tears. Peak concentrations and area-under-the-curve values of cephalexin, penicillin V, and penicillin G were reduced 40% to 60% in patients given milk and drug concurrently. Absorption was enhanced when erythromycin ethylsuccinate was given milk. After administration of both erythromycin formulations, penicillin V and ampicillin, salivary concentrations exceeded the minimal inhibitory concentrations for most pneumococci and group A streptococci and for many meningococci. The clinical implications of these pharmacokinetic data are discussed.