[Reproductive and developmental toxicity studies of T-3761 in rats]

We carried out reproductive and developmental toxicity studies (i.e. fertility study, teratological study, and perinatal and postnatal study) of T-3761, a new quinolone derivative, in S.D. rats. T-3761 was administered orally at the dose of 60, 300 and 1,500 mg/kg/day as suspension in 5% acacia solution. 1. Fertility study T-3761 was administered to male rats for 9 weeks prior to mating and to female rats for 2 weeks prior to mating and until day 7 of gestation. In parent rats, soft stools, slight depression of body weight gain and increase in water intake were observed at the dose of 1,500 mg/kg. Cecum weight was increased at the dose of 300 mg/kg and more in male and at the dose of 1,500 mg/kg in female. No effects on reproductive performance were discernible in the T-3761 treated groups. In fetuses, external, skeletal and visceral examinations revealed no teratological abnormalities. Slightly retarded ossification, however, was observed at the dose of 1,500 mg/kg. From these findings, the no-effect dose of T-3761 in fertility study was considered to be 300 mg/kg/day for parent rats and fetuses. 2. Teratological study T-3761 was administered from day 7 to day 17 of gestation. In dams, soft stools, transient decrease in food intake, increase in water intake, depression of body weight gain and increase in cecum weight were observed at the dose of 1,500 mg/kg. In fetuses, slight increase in incidence of ventricular septal defect and slightly retarded ossification were observed at the dose of 1,500 mg/kg. In the postnatal examination, there were no effects in the T-3761 treated groups. From these findings, the no-effect dose of T-3761 in teratological study was considered to be 300 mg/kg/day for dams and next generations. 3. Perinatal and postnatal study T-3761 was administered from day 17 of gestation to day 21 of lactation. In dams, cecum weight was increased at the dose of 300 mg/kg and more. And soft stools, transient decrease in food intake, increase in water intake, transient depression of body weight gain and slight extension of gestation period were observed at the dose of 1,500 mg/kg. In the postnatal examination, there were no effects in the T-3761 treated groups. From these findings, the no-effect dose of T-3761 in perinatal and postnatal study was considered to be 300 mg/kg/day for dams and more than 1,500 mg/kg/day for next generations.