Pharmacokinetics of ampicillin (2.0 grams) and sulbactam (1.0 gram) coadministered to subjects with normal and abnormal renal function and with end-stage renal disease on hemodialysis

Abstract

The single-dose pharmacokinetics of intravenously administered ampicillin (2.0 g) and sulbactam (1.0 g) were studied in normal subjects and in patients with various degrees of creatinine clearance (CLCR). Six normal subjects (CLCR, greater than 60 ml/min), six patients with mild renal failure (CLCR, 31 to 60 ml/min), four patients with severe renal failure (CLCR, 7 to 30 ml/min), and four patients requiring maintenance hemodialysis (CLCR, less than 7 ml/min) were studied. The terminal half-lives for ampicillin and sulbactam more than doubled in patients with severe renal failure compared with subjects with normal renal function and mild renal insufficiency. CLCR significantly correlated with ampicillin (r = 0.88) and sulbactam (r = 0.54) total body clearance. Mean steady-state volume of distribution and nonrenal clearance for ampicillin and sulbactam were not affected by renal function. Hemodialysis approximately doubled the ampicillin and sulbactam total body clearance. Mean totals of 34.8 +/- 4.0% of the ampicillin dose and 44.7 +/- 3.2% of the sulbactam dose were removed during a 4-h hemodialysis treatment. A slight rebound in concentrations in serum after hemodialysis was observed for both drugs in all four subjects. In hemodialysis patients, the ampicillin half-life was 17.4 +/- 8.0 h and the sulbactam half-life was 13.4 +/- 7.4 h. The ampicillin and sulbactam half-lives were appreciably altered during the hemodialysis period (means of 2.2 and 2.3 h, respectively). The nearly parallel decrease in total body clearance, with volume of distribution and nonrenal clearance remaining relatively constant, suggests that the same ratio of ampicillin to sulbactam is appropriate regardless of renal function. An adjustment of the ampicillin (2.0 g) and sulbactam (1.0 g) dose to twice daily would be appropriate in patients with a CLCR between 7 and 30 ml/min. Doses should be given every 24 h for those undergoing maintenance hemodialysis. On hemodialysis days, doses should be given after hemodialysis.