cyproterone

Cyproterone refers to a synthetic steroidal compound, commonly used in the form of cyproterone acetate (CPA). It possesses two principal pharmacological actions: antiandrogen activity, which blocks the effects of male sex hormones, and progestogenic activity, which activates progesterone receptors. CPA is often used alone in some countries and in combination with an estrogen in various oral contraceptives.

Mechanism of action requires two components. As an antiandrogen, CPA competitively inhibits androgen receptors, reducing androgen-driven effects on hair growth, skin sebum production, and other tissues. As a progestin, CPA suppresses the hypothalamic-pituitary-gonadal axis, lowering gonadotropin release and consequently reducing ovarian production of androgens and estrogens. The combined actions help manage conditions linked to excess androgens and can provide contraception in regimens that include estrogen.

Medical uses vary by country. In women, CPA is used to treat severe hirsutism and androgen-related acne and, in some regimens, to provide birth control in women with hyperandrogenic symptoms. It has also been used historically for hormone therapy in transgender women and, in higher doses, as part of androgen deprivation strategies for prostate cancer. In many regimens, CPA is administered with an estrogen compound to obtain contraception and additional antiandrogen effects. Availability and approved indications differ by regulatory authority.

Safety and adverse effects require careful monitoring. CPA can cause liver toxicity, including rare hepatic adenomas, and is contraindicated in significant liver disease or pregnancy. When used in estrogen-containing contraceptives, there is an elevated risk of venous thromboembolism. Other potential effects include mood changes, fatigue, weight gain, and changes in libido. Use requires individualized risk assessment and medical supervision.