chlormadinone acetate

Chlormadinone acetate is a synthetic progestin and antiandrogen used primarily in combination with estrogens for hormonal contraception and menopausal hormone therapy. It acts as a potent agonist of the progesterone receptor (PR), a partial antagonist of the androgen receptor (AR), and a weak antagonist of the glucocorticoid receptor (GR). Its main mechanism involves suppressing ovulation by inhibiting gonadotropin secretion from the pituitary gland. Chlormadinone acetate also exhibits antiandrogenic effects by blocking androgen receptors and reducing testosterone levels. Developed in 1961 by Schering, now part of Bayer, it was withdrawn from the US market due to safety concerns but remains widely used in other countries for its contraceptive efficacy and tolerability[2][3][5].

Brand names

BelaraEstalor-21Estalor21Estalor 21C-Quens

Other names

6-chloro-Δ6-dehydro-17α-acetoxyprogesterone17α-acetoxy-6-chloro-pregna-4,6-diene-3,20-dione