Relationship between pharmacokinetics and bioavailability of cefroxadine (CGP 9000) and renal function

The pharmacokinetics and bioavailability of cefroxadine were studied in 15 patients with different renal functions after administration of 0.5 g as oral capsules and as intravenous infusions. Microbiological assays by agar diffusion and high-pressure liquid chromatography may both be used for this agent since no metabolite can be found. The bioavailability is near 100% of the oral dose regardless of renal function. Urinary recovery varied from about 50% in renal glomerular filtration rates (GFR) of less than 7 ml/min to nearly 100% in normal renal function. The serum concentrations, serum elimination half-life and total body clearance were significantly influenced by reduced renal function. Nonrenal elimination occurred in reduced renal function; the maximum serum elimination half-life was 24.6 h. Dose modifications according to renal function are suggested with from three doses/24 in normal renal function to one dose/24 h in patients with GFR of 10 ml/min. The relative distribution volume corresponded to approximately 30% of the body weight. Tubular secretion of cefroxadine took place. The concentrations in urine remained above 32 mg/l for 12 h in all subjects regardless of renal function.