Moxalactam epimer disposition in patients undergoing continuous ambulatory peritoneal dialysis

The kinetics of the epimers of moxalactam ( R ‐MOX, S ‐MOX) were investigated in patients without infections who were receiving continuous ambulatory peritoneal dialysis after both intravenous and intraperitoneal injections of moxalactam. R ‐MOX and S ‐MOX were well absorbed from the peritoneal cavity, with mean systemic availability of 0.71 ± 0.18 and 0.79 ± 0.18, respectively. After intravenous MOX, serum clearance was 10.2 ± 3.4 ( R ‐MOX) and 10.9 ± 3.2 ( S ‐MOX) ml/hr/kg. Net time‐averaged peritoneal dialysis clearance of both epimers was minimal, about 10% of serum clearance. Serum and dialysate MOX concentrations were above the minimum inhibitory concentrations for susceptible bacteria for 24 hours after a 2.0 or 1.0 gm intravenous or intraperitoneal dose. Gastrointestinal side effects occurred after a 2.0 gm dose (both intravenous and intraperitoneal) but not after a 1.0 gm dose. There were no significant differences in the kinetics of R ‐MOX and S ‐MOX. A single 1.0 gm ip dose leads to serum and dialysate MOX concentrations above the minimum inhibitory concentration for susceptible pathogens for 24 hours. Clinical Pharmacology and Therapeutics (1985) 38, 150–156; doi: 10.1038/clpt.1985.151