Inhibition of human placental progesterone synthesis by danazol in vivo.

In vivo, a single dose of 1000 mg danazol was given orally to pregnant volunteers (n = 8) prior to a therapeutic abortion (8th-12th week of gestation). Changes in serum progesterone and estradiol were evaluated both by analysis of percentage values related to initial concentrations or statistically by a Kruskal-Wallis test comparing absolute steroid concentrations. Following treatment (n = 8), a significant decrease in mean plasma progesterone of about 20% was observed within 2-4 hours; progesterone levels varied between 80-120% during 24 hours in controls (n = 10); individual serum estradiol decreased up to 30% of control values 2 hours after danazol application. Changes in estradiol in controls versus tests were not statistically significant (p less than 0.05) when absolute estradiol concentrations were compared. Only a slight (10-20%) decrease in mean serum DHAS was found between 2 to 6 hours following danazol treatment. This study demonstrates the inhibitory activity of danazol on the human maternal and fetal steroidogenesis in vivo. The possible sites of action of danazol are discussed.