Pharmacokinetics, protein binding, and predicted extravascular distribution of moxalactam in normal and renal failure subjects

Ten normal subjects and ten patients with chronic renal failure requiring hemodialysis were given intravenous infusions of moxalactam ranging from 500 mg to 2 g. Serum and urine concentrations were measured for up to 12 h. Renal failure subjects were given doses both during and between hemodialysis treatments. Protein binding of moxalactam in both normal and uremic serum was determined by ultracentrifugation. The serum half-life in normal subjects was 2.1 and 2.3 h for the 1- and 2-g doses, respectively. The half-life of moxalactam in patients with renal failure was 13.9 h on the 500-mg dose and 13.3 h on the 1.0-g dose. During hemodialysis the serum half-life fell to 4.4 and 5.7 h, respectively. Moxalactam protein binding ranged from 52% in normal serum to 36% in renal failure patient serum. Unbound moxalactam appeared to distribute with the entire body water based on the serum pharmacokinetics and antibiotic serum protein binding determined in this study.