[Teratogenicity study on halopredone acetate in rats].

A teratogenicity study of halopredone acetate (THS-201), a synthetic corticosteroid, was carried out using Jcl: Wistar rats. Pregnant rats were treated subcutaneously in doses of 0.1, 0.5, 2.5 and 12.5 mg/kg/day, from day 7 to day 17 of gestation. Two-thirds of pregnant rats were killed on day 20 of gestation to examine the development of fetuses, and remaining rats were allowed to litter naturally in order to investigate the postnatal development of offspring. The results obtained from the present study were as follows. During the gestation and lactation periods, there occurred a decrease in the maternal body weight gain in 2.5 and 12.5 mg/kg groups. No influences of THS-201 administration were observed on gestation, delivery and lactation of dams. No external, visceral and skeletal anomalies attributable to THS-201 were observed in the fetuses. THS-201 administration did not have any influences on viability and development, various functions such as reflex response, learning and reproductive performance of F1 generation, and further on development of F2 generation. Therefore, it was concluded that the non-effect dose of THS-201 for the reproduction of dams and development of F1 generation was 12.5 mg/kg/day.