Disposition of intravenous and intraperitoneal cefoxitin during chronic intermittent peritoneal dialysis

The disposition of intravenous and intraperitoneal administered cefoxitin was evaluated in four males undergoing intermittent peritoneal dialysis. Each patient received 1 g of cefoxitin intravenously prior to an eight-hour dialysis; subsequently, one patient received another 1 g intravenous dose prior to an 18-hour dialysis while each of the other three patients had 100 mg of cefoxitin added to their eight hourly exchanges of dialysis fluid with 2 L per exchange. Serial blood, dialysate, and urine samples were collected and analyzed for cefoxitin by a microbiologic assay. Twenty-four hours after intravenous administration, serum cefoxitin concentrations were greater than 16 micrograms/mL (therapeutic breakpoint) in each patient. Mean cefoxitin dialysate concentrations averaged 7.8 +/- 3.8 micrograms/mL and were greater than 16 micrograms/mL in only 2 of 43 exchanges. After intraperitoneal administration, serum cefoxitin concentrations were highest after the eighth exchange (range 5.6 to 10.6 micrograms/mL). Thus, diffusion of cefoxitin across the placental membrane was not extensive. Dialysis removed only 10% to 20% of the intravenous dose.