Inhibition of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity in first- and second-trimester human pregnancy and the luteal phase using Epostane.

The effects of a competitive inhibitor of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) (Epostane, Sterling Winthrop, Guildford, England) on serum progesterone (P), estradiol (E2), and cortisol have been studied in three groups of pregnant women awaiting termination of pregnancy (5 to 8 weeks, 8 to 12 weeks, and 12 to 18 weeks of pregnancy) and 15 women in the luteal phase of the menstrual cycle. A single-dose randomized double-blind study was performed, each woman receiving a placebo, 50 mg of Epostane, or 100 mg of Epostane. In the pregnant group, there was a significant decline in the serum P concentration after both 50 mg and 100 mg of Epostane. The percentage fall increased with both drug dosage and advancing gestation. A similar fall in serum E2 was observed. Both of these effects were temporary. In the luteal phase group, a significant decline in serum P was observed after 100 mg of Epostane, but the serum E2 was not significantly different from the pretreatment concentration. Serum cortisol did not differ significantly from control values. These findings suggest that Epostane is an effective inhibitor of placental and ovarian 3 beta-HSD, which may have a role as an interceptive agent.