Further studies on a new bioassay of progestational activity (traumatic deciduoma formation in immature rats)

Six synthetic steroids were tested subcutaneously in a new bio-assay for short- and long-lasting progestational activity, using traumatic deciduoma production in immature female rats. As reference standard, a daily subcutaneous dose of 0.25 mg progesterone regularly induced a distinct deciduomagenic effect. A single dose of 12.5 mg of progesterone showed a prolonged activity. Medroxyprogesterone acetate showed a distinct deciduomagenic effect at the 0.05 mg daily s.c. dose level; a distinct prolonged effect was induced with a single s.c. injection of 0.5 mg. 16alpha-Aethylprogesterone induced regularly decidual reaction at the 0.1 mg s.c. dose level, it showed prolonged activity at the 0.25 mg dose level. The daily threshold dose for chlormadinone acetate was 0.25 mg; prolonged activity was shown with 2.5 mg. The daily threshold dose for duphaston is between 0.5 mg and 1.0 mg. A single s.c. dose of as much as 20.0 mg of 17alpha- hydroxyprogesterone caproate did not have a deciduomagenic effect.