Bicalutamide and feminizing hormone therapy
Bicalutamide is an anti-androgen drug which means that it blocks the effect of androgenic hormones such as testosterone and DHT. The important thing to understand is that bicalutamide does not lower testosterone levels, it simply blocks the effect of testosterone on tissues. In many cases, Testosterone levels initially increase after starting this medication however, that is nothing to be concerned about. Testosterone levels start declining over time, this change happens much more rapidly if you’re also taking estrogen and progesterone in addition to bicalutamide
Bicalutamide is most commonly used for treating men with prostate cancer
Off-label uses:
- Puberty blocker
- Feminization therapy
- Androgenic Alopecia in females
- Acne Reduction
Today primarily will be focusing on bicalutamide use in transgender females
Other anti-androgen medications often prescribed are spironolactone and cyproterone acetate. However, these drugs are much weaker than bicalutamide. Cyproterone is also not available in the US.
Bicalutamide also helps the aromatization of testosterone to estrogen which is why it is especially helpful for breast development when compared to other anti-androgen medications. Some small studies have shown better breast growth when compared to Aldactone and cyproterone. A possible mechanism is that Aldactone causes early maturation of the breast bud when compared with bicalutamide.
Comparison of anti-androgen effect of bicalutamide, Aldactone, and Cyproterone in transgender females.
Breast development with bicalutamide therapy
Bicalutamide is known to cause a reduction in vitamin C levels and glutathione levels in animal studies. Taking glutathione and vitamin C may reduce the risk of liver toxicity however I have no data to support this strategy.
Key Benefits:
- better Breast development when compared to spironolactone and Cyproterone.
- Reduced acne
- Reduce facial hair
Duration of Effect:
Half-life is 6 days so the drug stays in the body for several days so only twice a weekly dose is adequate. Compare that to spironolactone which has a half-life of only 2 hours
Contraindications:
Do not use or use caution if you
- Have Liver problems
- If you drink heavily
- Over the age of 35
Lab Testing when on bicalutamide
Get a liver panel done 2-4 weeks after starting the medication. For any sign of liver failure such as jaundice, the medication must be immediately stopped.
Dosing:
Bicalutamide stays in the body for several days and has a half-life of 6 days which means half of the drug is broken down and removed by the body in 6 days. Twice a weekly dose of 50 mg is adequate. Higher doses increase the risk of liver toxicity and should be avoided
In summary, this is a very good medication for feminization therapy especially if high breast growth is strongly desired. Liver toxicity is a major concern and can be life-threatening so do not consume alcohol, and avoid hepatotoxic medications such as Tylenol.
