Pharmacokinetic studies of cefoxitin in continuous ambulatory peritoneal dialysis

The pharmacokinetics of cefoxitin was examined in 9 patients undergoing peritoneal dialysis for chronic renal failure. Cefoxitin was administered intraperitoneally in the dialysate fluid every 6 h for 24 h, in two different concentrations, 50 micrograms/ml and 100 micrograms/ml. The plasma half-life of cefoxitin was 20.2 h. The major route of elimination was non-renal, with a clearance of 8.0 ml/min. Peritoneal clearance was 4.1 ml/min. As expected, renal clearance was negligible. The peak plasma concentrations of cefoxitin at the two dose levels used were 7 micrograms/ml and 15 micrograms/ml, respectively, when assayed by HPLC, and 12 micrograms/ml and 24 micrograms/ml when determined by a microbiological assay. The cefoxitin concentration in the dialysate decreased from 50 micrograms/ml to 14 micrograms/ml and from 100 micrograms/ml to 37 micrograms/ml during the 6 h of its retention in the peritoneal cavity.