[Biological activities of chlormadinone acetate. (I). Analysis of hormonal activities].

Biological activities of 17a-acetoxy-6-chloro-pregna-4,6-diene-3,20-dione (chlormadinone acetate ; CMA) were investigated in comparison with those of 17a-acetoxy-6a-methylpregnane-3,20-dione (medroxyprogesterone acetate ; MAP). CMA produced marked progestational activity either subcutaneously or orally in the uterine carbonic anhydrase test, and its relative potency is approximately 30 times the activity of progesterone in the subcutaneous assay and about 40 times the activity of norethisterone in the oral assay. CMA also possessed more activity than MAP in oral route. Deciduomatogenic activities of these two steroids subcutaneously injected into the mice were approximately the same, and their relative potencies against progesterone were approximately 4. Antigonadotropic activity of CMA was almost equal to that of progesterone administered subcutaneously either in the subcutaneous or in the oral test with parabiotic mice. MAP, however, produced marked activity of gonadotropin inhibition in the subcutaneous test but was as active as CMA in the oral route. In the ACTH-inhibition test in rats, CMA was less active than MAP either by subcutaneous or by oral route. Other hormonal activities such as androgenic, myogenic, estrogenic or anti-inflammatory were not manifested by the CMA treatment. Both CMA and MAP had no anesthetic activity in mice. These data suggest that CMA is a potent orally active progestational substance with a negligible activity to suppress pituitary ACTH and gonadotropin secretion. (pp. 1079--,,1093)