[Toxicity study of cefmatilen hydrochloride hydrate (S-1090) (3)--One- and three-month repeated oral dose toxicity studies in rats].

One- or three-month repeated oral dose toxicity studies of Cefmatilen hydrochloride hydrate (S-1090) in rats were conducted. Doses were set at 80, 200, 500 and 1250 mg potency/kg/day in the one-month toxicity study, and 100, 300 and 1000 mg potency/kg/day in the three-month toxicity study. Body weights increased favorably and no deaths occurred in all treated groups of both studies. The changes observed in both studies were soft feces, abdominal distention, increased food and water consumption, decreases of urine volume and pH, and a decrease of blood neutrophils in almost all treated groups, reddish-brown feces (due to chelated products of S-1090 and its decomposition products with Fe3+ in the diet) in groups dosed at 300 mg potency/kg or more, and a lower mature granulocyte ratio in the bone marrow in groups dosed at 1000 mg potency/kg or more. In necropsy, cecal enlargement with a large amount of muddy content was observed in all treated groups of both studies. In the three-month toxicity study, elevated drug-metabolizing enzyme activities were noted in the liver of the males in the 1000 mg potency/kg group. These changes were slight except for the cecal enlargement and the rats recovered well with drug withdrawal. Since no toxicologically significant changes were noted in either study, the NOAEL of S-1090 was estimated to be 1250 mg potency/kg/day in the one-month toxicity study and 1000 mg potency/kg/day in the three-month toxicity study.