Absorption of intraperitoneal antibiotics

The treatment of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) usually includes the repeated administration of intraperitoneal (ip) antibiotics. The initial segment of this study (15 noninfected CAPD patients) examined the ip administration of four structurally different agents that represent the common types of antibiotics prescribed for peritonitis: an aminoglycoside (tobramycin), a glycopeptide (vancomycin), a beta-lactam (cefamandole), and an oxa-beta-lactam (moxalactam). Subsequently, 16 CAPD patients with peritonitis received either vancomycin (30 mg/kg) or cefamandole (1 g) in two liters of dialysate over a six-hour dwell period. Vancomycin and cefamandole were absorbed more rapidly in patients with peritonitis as indicated by a more rapid decline in dialysate concentrations, and higher serum concentrations that occurred earlier than in the noninfected patients. Although a higher percentage of the ip dose of vancomycin and cefamandole was absorbed during peritonitis, peak serum concentrations at the end of the drug administration dwell period were not significantly different. Numerous factors influence the absorption of ip antibiotics, including the dialysate drug concentration, the dwell period, protein binding, distribution volume, and presence or absence of peritonitis.