[Toxicity study of cefmatilen hydrochloride hydrate (S-1090) (7)--Three-month repeated oral dose toxicity study in juvenile dogs].

To evaluate the repeated oral dose toxicity of Cefmatilen hydrochloride hydrate (S-1090) in juvenile dogs, S-1090 was administered to juvenile beagle dogs at dose levels of 50, 100, 200 and 400 mg potency/kg/day for 3 months. No deaths occurred. Urinalysis in the 400 mg potency/kg group revealed positive reactions of occult blood and protein, and erythrocytes in sediments. Cystitis was observed in the 200 and 400 mg potency/kg groups. In the thyroids, an increased weight in some animals in the groups dosed at 100 mg potency/kg or more and an increased follicular colloid in the 400 mg potency/kg group were observed. However, no related changes were noted in other examination items. Red to dark-red feces (due to chelated products of S-1090 or its decomposition products with Fe3+ in the diet) were observed in all treated groups. Plasma S-1090 concentrations increased in a manner less than dose-proportional. The lesions of urinary bladder were judged as S-1090-induced toxic changes and the NOAEL of S-1090 in this study was assessed to be 100 mg potency/kg/day.