Sulbactam is a new beta-lactamase inhibitor. The pharmacokinetic characteristics of sulbactam was similar to ampicillin after a single intravenous injection of 200 mg/kg in mice with a half-life of approximately 50 min. The two drugs appear to equilibrate rapidly between central and peripheral compartments. The Vc and Vd suggest that they are widely distributed in the extracellular fluid and into tissues. Co-administration of sulbactam and ampicillin in mice and in dogs showed essentially no change on the kinetics of either ampicillin or sulbactam.