Androgen receptor blockers: Spironolactone and Bicalutamide
This page looks at the category of androgen blockers that act by blocking the reception of androgens and not its production
Androgen blockers and progestogens
This is a summary of the different antiandrogen medications used in feminizing HRT. Follow the links below for detailled information on each medication.
In order for estrogens to be efficient, the action of testosterone MUST be blocked, one way or the other.
If monotherapy does not work for you, the solution can lie in anti-androgens, or androgen blockers - sometimes only refered to as blockers. Blockers actually encompass a great variety of medications, working in differents ways.
It is usually considered that orchiectomy or vaginoplasty allows for stopping anti-androgens, but not estrogens. It is in reallity a bit more complicated, and you can refer to the page on DHEA and intracrinology to know more about this issue.
Summary table of androgen blocking alternatives
| Name | Description | Risks |
|---|---|---|
| ✅ Monotherapy | High dose estrogen without blockers - uses the negative feedback mechanism of the body | Low increase of thromboembolic events, especially with very high doses. |
| ✅ Bicalutamide | Very efficient androgens blocker. Blocks the reception of androgens. | Low - but monitoring of liver fuction remains important |
| ✅ GnRHA | “Puberty blockers”, but can be used by transfem of any age to block the production of androgens. Usually delivered as injectable, sometimes nasal spray | Low |
| 😐 Spironolactone | Diuretic with an anti-androgen side-effect | Risks of hyperkalemia (excess of potassium, with variable risks), and reduced blood pressure |
| 😐 Progestogens (others than Androcur) | Very commonly prescribed anti-androgens. Work on the same basis as monotherapy, but with more side effects. | Risks of depression, hyperprolactinemia and liver failure |
| ❌ Finasteride | Useful against “male pattern hair loss”, otherwise not very efficient | Risks of depression and neurological problems |
| ❌ Dutasteride | Useful against “male pattern hair loss”, otherwise not very efficient | Risks of depression and neurological problems |
| ❌ Androcur | A very commonly prescribed synthetic progestogen, officially unadvised by many countries | Risks of depression, meningioma (meninges tumor) and liver failure |
| ❌ Flutamide | Obsolete medication (discontinued in Sweden) | High risks of liver failure. |
We can sort androgens blockers in 4 groups, according to their mode of actions:
- Androgen receptor blockers (Bicalutamide, Spironolactone)
- GnRH agonists and antagonists (also called Puberty blockers)
- Inhibitors of 5a-reductase (Finesteride, Dutasteride)
- Progestogens (among which Cyproterone Acetate or Androcur) We will now go through all of them, group by group.
Inhibitors of 5a-reductase: Finasteride and Dutasteride
This section is about the category of blockers that works by inhibiting the enzyme 5a-reductase
GnRH agonists and antagonists (“Puberty blockers”)
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Synthetic progestogens (Androcur...)
About synthetic progestogens (among which Androcur or cyproterone acetate) as used as androgen blockers
Last modified September 13, 2023: Content fix and logo (58bc167)