Concentrations of ampicillin and sulbactam in serum and in various compartments of the respiratory tract of patients.

After infusion of 2 g ampicillin and 1 g sulbactam the concentrations of these two beta-lactams were determined in serum and various compartments of the respiratory tract of 22 patients. About 30 min after the end of the infusion in 15 patients the mean serum concentration of ampicillin was 97 +/- 9.5 mg/l and of sulbactam 37.6 +/- 3.8 mg/l; in the biopsy samples of bronchial mucosa the concentration of ampicillin was 38.6 +/- 7.2 mg/kg and of sulbactam 28.1 +/- 5.2 mg/kg; in bronchial fluid the concentration of ampicillin was 0.6 +/- 0.1 mg/l and of sulbactam 0.3 +/- 0.1 mg/l (n = 15). In a further seven patients serum and pleural empyema samples were analysed and compared. The mean values of Cmax attained 1 to 2 h after the end of the infusion in pleural empyema were 7.6 +/- 3.1 mg/l and 6.2 +/- 1.6 mg/l for ampicillin and sulbactam, respectively. The two beta-lactams were eliminated markedly more slowly from empyema than from serum. These results show that ampicillin and sulbactam rapidly penetrate into various compartments of the respiratory tract and reach therapeutically active concentrations. The ratio of their concentrations (2:1) is largely the same as that in serum. The pharmacokinetic data therefore support the use of ampicillin/sulbactam in the perioperative prophylaxis and the treatment of bacterial infections of the lower respiratory tract.