Anti-androgens

Antiandrogens are a class of drugs that prevent masculinization due to androgens such as testosterone or DHT.

Mechanism of action
Note: these summaries apply only to people with testes. People with ovaries and people with no gonads will have a different response to these drugs.

Spironolactone
Spironolactone has two primary factors that contribute to its antiandrogenic activity:


 * Androgen receptor partial agonism: Spironolactone binds to the androgen receptor and causes it to express much more weakly than if an androgen such as testosterone or DHT had bound to it.
 * 17α-hydroxylase and 17,20-lyase inhibition: These two enzymes are key in the steriodogenesis of androgens (and estrogens and some glucocorticoids).

Cyptoterone acetate
Cyproterone acetate has two primary factors that contribute to its antiandrogenic activity:


 * Androgen receptor partial agonism: Cyproterone acetate binds to the androgen receptor and causes it to express much more weakly than if an androgen such as testosterone or DHT had bound to it.
 * Progestogenic activity: Cyproterone acetate acts as a progestogen, inducing negative feedback on the HPG axis and causing the body to produce less testosterone.

Bicalutamide
Bicalutamide is an androgen receptor antagonist. It binds to the androgen receptor and prevents it from expressing.

Leuprorelin
Leuprorelin is a GnRH agonist. It induces strong positive feedback on the HPG axis, which causes an increase in LH, FSH, and testosterone levels. After some time, the body downregulates the GnRH receptor, causing LH, FSH, and testosterone levels to drop.

Triptorelin
Triptorelin is a GnRH agonist. See for mechanism of action.

Goserelin
Goserelin is a GnRH agonist. See for mechanism of action.

Finasteride
Finasteride is a 5α-reductase inhibitor. 5α-reductase is an enzyme involved in the biosynthesis of DHT from testosterone. DHT is a more potent androgen receptor agonist than testosterone.

Note that finasteride does not prevent testosterone from binding to the androgen receptor, so finasteride alone is insufficient to prevent masculinization.

Dutasteride
Dutasteride is a 5α-reductase inhibitor. See for mechanism of action.

Note that dutasteride does not prevent testosterone from binding to the androgen receptor, so dutasteride alone is insufficient to prevent masculinization.

Estradiol
Estradiol is a antigonadotropin. It induces negative feedback on the HPG axis, which causes the body to produce less testosterone.