Serum and dialysate concentrations of cephalexin following repeated dosing in CAPD patients.

Oral cephalexin, 1 to 2 g daily for 3 days, was given to six stable, noninfected patients receiving maintenance continuous ambulatory peritoneal dialysis (CAPD). The peak serum concentration after a 2 g initial dose was between 73 and 123 mg/L. On the second and third day in five patients who received a 2 g daily oral dose, the serum concentrations were between 35 and 118 mg/L in serum obtained 1 to 1.5 hours after the dosing. Similar serum concentrations were seen in one patient who only received a 1 g oral dose on the second and third day. Cephalexin concentrations in the peritoneal dialysate reached a peak on the first day between 4 to 14 hours after the dose and were between 31 to 78 mg/L. During the second and third day, the highest cephalexin concentration was 118 mg/L and the lowest was 12 mg/L. The data are consistent with the feasibility of oral cephalexin for treatment of CAPD-associated peritonitis with microorganisms that are sensitive to these levels of cephalexin.