Evaluation of cefoxitin nephrotoxicity in experimentally induced renal failure.

The nephrotoxicity of cefoxitin was studied in a rat model of impaired renal function. Two levels of renal impairment were produced: "moderate," with blood urea concentrations of 100 to 150 mg/100 ml (16.7 to 25.1 mmol/liter) and glomerular filtration rates 25 to 35% of normal, and "severe," with blood urea concentrations greater than 150 mg/100 ml (greater than 25.1 mmol/liter) and glomerular filtration rates 10 to 20% of normal. Sham-operated animals were used as controls. Three dose schedules of cefoxitin were administered to these controls--500, 1,000, and 2,500 mg/kg per day administered as a divided dose for 5 days. Doses given to the moderately and severely uremic animals were adjusted so that serum levels of cefoxitin were similar to those attained in the sham-operated control animals. Concentrations of urea and creatinine in blood, glomerular filtration rates, and the urinary concentrating capacities of the experimental animals were monitored before and after cefoxitin treatment. There was no evidence of nephrotoxicity in even the most challenging experiment, in which blood serum levels of cefoxitin reached 2,000 microgram/ml in animals, with 15% renal function. These findings support available clinical data, suggesting that cefoxitin can be administered safely to patients with compromised renal function.