Anti-androgens
 |
Wikipedia also has an article on this topic. |
 |
This is a note! It contains the early rough scribblings of an article, which you could grow to a more thorough page, or simply deranged science musings! ❤ |
Antiandrogens are a class of drugs that prevent masculinization due to androgens such as testosterone or DHT.
Overview
| Class | Route of administration | Availability | Notes | |
|---|---|---|---|---|
| Spironolactone | Steroidal antiandrogen | Oral | Readily available | Most common antiandrogen in the US. |
| Cyproterone acetate | Steroidal antiandrogen | Oral, intramuscular injection | Readily available | Not approved by the FDA in the US. Common outside of the US. |
| Bicalutamide | Nonsteroidal antiandrogen | Oral | Readily available | Not frequently prescribed to trans people. |
| Enzalutamide | Nonsteroidal antiandrogen | Oral | Available | No instances of it being prescribed to trans people in medical literature. |
| Darolutamide | Nonsteroidal antiandrogen | Oral | Phase III trials | |
| Flutamide | Nonsteroidal antiandrogen | Oral | Available | Uncommon because it is metabolized quickly |
| Leuprorelin | GnRH agonist | Injection, implant | Available | Frequently used to block puberty. |
| Triptorelin | GnRH agonist | Injection | Available | |
| Goserelin | GnRH agonist | Implant | Available | |
| Finasteride | 5α-reductase inhibitor | Oral | Readily available | Often prescribed for hair loss. |
| Dutasteride | 5α-reductase inhibitor | Oral | Readily available | Sometimes prescribed for hair loss. |
| Estradiol | Antigonadotropin | Oral, sublingual, injection, implant, transdermal, others | Readily available |
Mechanism of action
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 steroidogenesis 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. In people with testes, this results in lower testosterone levels. In people with ovaries, this results in lower estrogen levels.
Bicalutamide
Bicalutamide is a nonsteroidal androgen receptor antagonist. It binds to the androgen receptor and prevents the expression of AR-regulated genes.
Enzalutamide
Enzalutamide is a nonsteroidal androgen receptor antagonist. It binds to the androgen receptor and prevents the expression of AR-regulated genes.
Darolutamide
Darolutamide is a nonsteroidal androgen receptor antagonist. It binds to the androgen receptor and prevents the expression of AR-regulated genes.
Leuprorelin
Leuprorelin is a GnRH agonist. It induces strong positive feedback on the HPG axis, which causes an increase in LH, FSH, testosterone (in males), and estrogen (in females) levels. After some time, the body downregulates the GnRH receptor, causing LH, FSH, endogenous testosterone (in males), and endogenous estrogen (in females) levels to drop.
Triptorelin
Triptorelin is a GnRH agonist. See #Leuprorelin for mechanism of action.
Goserelin
Goserelin is a GnRH agonist. See #Leuprorelin 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 #Finasteride 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 (in males) or estrogen (in females).