A 25-year-old woman with idiopathic hirsutism is prescribed a combined oral contraceptive containing cyproterone acetate. The anti-androgenic action of cyproterone acetate differs from drospirenone in which key pharmacological respect?

• A Cyproterone acetate inhibits 5-alpha reductase while drospirenone inhibits aromatase
• B Cyproterone acetate works by suppressing ovarian androgen production only, while drospirenone blocks peripheral androgen receptors
• C Cyproterone acetate is a steroidal anti-androgen with progestogenic activity and androgen receptor antagonism, while drospirenone is a spironolactone analogue with anti-mineralocorticoid activity ✓
• D Cyproterone acetate is a GnRH agonist while drospirenone is an androgen receptor antagonist

Explanation

Cyproterone acetate is a steroidal progestin with direct androgen receptor antagonism and suppresses gonadotropins, reducing ovarian androgen production. Drospirenone is a spironolactone derivative with anti-mineralocorticoid and mild anti-androgenic activity, but its primary contraceptive action is progestogenic suppression of ovulation. Neither is a 5-alpha reductase inhibitor (that is finasteride) nor a GnRH agonist. Cyproterone acetate is used in combined OCPs (with ethinyl estradiol) in many countries for hirsutism and acne, though not FDA-approved in the US.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

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