Seven adult patients on continuous ambulatory peritoneal dialysis (CAPD) received one dose of pefloxacin, a novel quinolone antibiotic, orally and intravenously on two separate occasions to characterize the pharmacokinetics and metabolism of the drug. Concentrations of both pefloxacin and its active metabolite N-desmethyl-pefloxacin (norfloxacin) were measured in serum and dialysate by HPLC. Half-life, total body clearance and peritoneal clearance were determined. The overall elimination half-life was 19.9h. Relative to the IV dose the bioavailability following oral administration of pefloxacin was 76%. The mean serum and dialysate concentrations were similar up to 24 h after the oral or IV dose. After a 6-h dwell time the dialysate concentration of pefloxacin was 2.24 mg/L which is above the MIC90 for most bacteria responsible for peritonitis in CAPD patients. The peritoneal clearance of pefloxacin averaged 2.5 mL/min. Serum concentrations of the metabolite norfloxacin were less than 0.5 mg/L during the 24 h study period. We conclude that pefloxacin might be equally effective in the treatment of peritonitis of CAPD after oral or IV administration. Since the peritoneal clearance contributes insignificantly to the elimination of pefloxacin during CAPD, the proposed maintenance regimen of an oral or IV 400 mg dose/day seems to be a reasonable therapy for infections in CAPD patients.

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