The pharmacokinetics of bacampicillin.

Bacampicillin is an ethoxycarbonyloxyethyl ester of ampicillin that is rapidly converted to free ampicillin, the active agent, by nonspecific esterases present in serum and in the intestinal wall. The compound is absorbed more rapidly than ampicillin, with peak absorption occurring 45 min to 1 hr after administration of the drug, whereas the peak after administration of the parent compound is at 2 hr. Peak levels of drug in serum after a 400-mg dose of bacampicillin (molar equivalent, 278 mg of ampicillin) are 6-8 micrograms/ml. Peak levels after an 800-mg dose of bacampicillin (molar equivalent, 556 mg of ampicillin) are 11-14 micrograms/ml. These peak levels are twofold greater than those achieved with equimolar doses of ampicillin. Ingestion of bacampicillin with food does not decrease or delay absorption of the drug. Recovery of ampicillin in urine after ingestion of bacampicillin is 75% vs. a recovery of 45% after ampicillin. Ampicillin appears earlier in tears, saliva, bronchial and maxillary sinus secretions, middle ear fluid, skin blisters. lymph, and urethral and cervical secretions, and the levels obtained in these tissues are greater after ingestion of bacampicillin than after ampicillin. The pharmacokinetics of bacampicillin and ampicillin in the period 2.5-8 hr after their ingestion is virtually identical at equimolar doses.