CLIMACTERIC 2005;8(Suppl 1):3–63
Pharmacology of estrogens and progestogens: influence of different routes of administration
"In contrast to MPA and megestrol acetate, the progesterone derivative CMA has some antiandrogenic
activity which corresponds to 20–30% of that of CPA."
CMA is short for chlormadinone acetate. MPA is short for medroxyprogesterone acetate (Provera). CPA is short for cyproterone acetate (Androcur).
Also according to
J Steroid Biochem. 1987 Oct;28(4):379-84.
"It should be added that MPA, megestrol acetate and CMA are completely devoid of antiandrogenic activity".
In this context, it means that CMA (chlormadinone acetate) does not block androgen from binding to androgen receptors like Androcur (cyproterone acetate) or Spiro does. Spiro is a weaker blocker than Androcur.
Also noted in this study which is a little worrying but should be investigated further
"In agreement with glucocorticoid activity, MPA, megestrol acetate and CMA caused a marked inhibition (45-64%) of adrenal weight".
Ann N Y Acad Sci. 2003 Nov;997:292-306.
Androgens and antiandrogens
"Cyproterone acetate (CPA) is the most potent antiandrogenic progestin, followed by dienogest, drosperinone, and chlormadinone acetate."
In conclusion, CMA reduces androgen like Androcur and Spiro but does not block androgen at receptors or at least, weakly as compared to Androcur, perhaps 1/5 to 1/3 that of Androcur.