[Fertility study on halopredone acetate in rats].

A fertility study of halopredone acetate (THS-201), a synthetic corticosteroid, was carried out using Jcl: Wistar rats. Male rats were treated subcutaneously for 63 days before mating and throughout mating, and female rats were treated subcutaneously for 14 days before mating and until day 7 of gestation, in doses of 0.04, 0.2, 1.0 and 5.0 mg/kg/day. Male and female rats in the same dose were mated. All of the pregnant rats were killed on day 20 of gestation and their fetuses were examined morphologically. The results obtained from the present study were as follows. A decrease in body weight gain was observed in male rats of 1.0 and 5.0 mg/kg groups, compared to the vehicle control group. In female rats of 5.0 mg/kg group, a decrease in body weight gain during gestation period was observed. However, no influences attributable to THS 201 administration were observed on the fertility and fetal development. These results indicated that the non-effect dose of THS-201 for the fertility of rats and fetal development was 5.0 mg/kg/day.