N. SookvanichsilpO. P. MatangkasombutMahidol University2018-02-272018-02-271986-01-01Contraception. Vol.34, No.2 (1986), 191-198001078242-s2.0-0023019372https://repository.li.mahidol.ac.th/handle/20.500.14594/9812Diazepam, a well known tranquilizer, and ethinyl estradiol have frequently been prescribed together in rape cases. These two drugs were reported to possess an opposite action on uterine motility. Phenobarbital, a typical enzyme inducer, has been prescribed together with ethinyl estradiol in some cases as a sedative-hypnotic. The present study was, therefore, designed to investigate the possible interferences of diazepam or phenobarbital sodium on postcoital contraceptive efficacy of ethinyl estradiol (4 μg/kg/day) in rats. All tested doses of diazepam (1, 2 and 4 mg/kg/day) or phenobarbital sodium (30 and 60 mg/kg/day) appear to have no effect on the efficacy of ethinyl estradiol when either of them was administered from D 3 to D 5 or from D 1 to D 5 of pregnancy. In addition, neither diazepam nor phenobarbital sodium at the highest doses used showed an effect on pregnancy. © 1986.Mahidol UniversityMedicineArticleSCOPUS10.1016/0010-7824(86)90071-5