An evaluation of the toxicity of cefaclor in laboratory animals

The toxicity of cefaclor, a new orally-administered cephalosporin, was evaluated in laboratory animals given single or multiple doses of the antibiotic. The acute toxicity data for cefaclor in mice, rats, dogs and monkeys were comparable to that previously reported for cephalexin. Rats were maintained on dietary mixtures of cefaclor which provided average daily doses of approximately 230 to 950 mg/kg for 28 days in subacute toxicity tests, and 160 to 675 mg/kg for 1 year in chronic toxicity tests. Treatment-related effects in the above studies were limited to soft stool excretion and caecal dilatation in the subacute test. Effects in dogs given daily oral doses of 50 to 200 mg/kg for 30 days were limited to a transient moderate fall in haemoglobin concentration in the two males at the highest dose. Soft stool excretion and occasional episodes of emesis were observed in dogs given cefaclor for 1 year at oral doses of 100 to 400 mg/kg/day. A reversible thrombocytopenia occurred in one animal at the highest dose. Analysis of various tissue fluids taken 2 hours after the last dose revealed that the concentration of cefaclor in the synovial fluid was approximatley one-half of that in serum. The results of these studies indicate that cefaclor has a low toxic potential in the species tested.