A 4-week intravenous toxicity study of the active metabolite (NM394) of prulifloxacin (NM441) in rats followed by a 4-week recovery test

Abstract

A repeated dose toxicity study of ( +/- )-6- fluoro-1-methyl-4-oxo-7-(1-piperazinyl)-4H- [1,3]thiazeto[3,2-a]quinoline-3-carboxylic acid (NM394), the active metabolite of a new antibacterial agent, prulifloxacin, was conducted in Sprague-Dawley rats. Male and female rats were given the test material intravenously for 4 weeks at doses of 0 (control), 3, 10 and 30 mg/kg. After discontinuation of the treatment, a 4-week recovery test was also conducted. There were no treatment-related effects on survival, clinical signs, body weight and food consumption. Ophthalmoscopic and hematologic examinations failed to show any abnormalities related to the treatment. Increased water consumption was observed in the 10 and 30 mg/kg groups. In these dose groups, increased urine volume and lowered urine specific gravity, and crystalline substance and small epithelial cells in urinary sediments were seen. Cloudy urine was also seen in the 30 mg/kg group. Blood chemical examination showed decreased gamma-globulin in the 10 and 30 mg/kg groups and increased BUN and creatinine in the 30 mg/kg group. Pathological changes caused by the treatment were as follows. In kidney, tubular nephrosis with crystalline substance was observed in the 10 and 30 mg/kg groups and its organ weight was increased in the 30 mg/kg group. Cecal weight was increased in the 30 mg/kg group. The above-mentioned changes were reversible except for decreased gamma-globulin. Plasma levels and urinary concentrations of the test material were increased in all dose groups with dose-related manner, whereby no sex differences were observed. No effects caused by the repeated dosing were seen in the plasma concentrations. Toxicological findings were not observed in the 3 mg/kg group. The results show that the NOAEL of NM394 is 3 mg/kg for 4-week repeated dose toxicity in rats.