Bicalutamide
Bicalutamide is an antiandrogen (testosterone blocker). Unlike most antiandrogens, it does not lower the body’s production of testosterone. Instead, it stops the hormonal action of testosterone (and other androgens like DHT), causing it to be present, but hormonally inactive. Bicalutamide is as effective as other antiandrogens (Cockshott, 2004).
Key points
- Does not lower testosterone levels
- Renders testosterone (and other androgens such as DHT) inactive
- Requires ongoing liver function monitoring
- Rarely prescribed in trans people due to risk profile
Dosing
Bicalutamide is a pill that is swallowed. Trans people most commonly take it at a dose of 50 mg once daily, and don’t usually need more than that. Rarely, some people have taken both lower and higher dosages ranging from 25 mg daily to 150 mg daily (Aly, 2020).
Bicalutamide stays in the body for a long time. It can take well over a month to build up when first taken, and to break down when stopped (Cockshott, 2004; Graphs).
Risks & management
Bicalutamide has a very small risk of causing life-threatening injury to the liver. When taking bicalutamide, it is extremely important that liver function is regularly checked using a blood test called "alanine aminotransferase" (ALT), especially in the first four months. Bicalutamide should be stopped immediately if yellowing of the skin occurs, or ALT levels become higher than twice the normal upper limit (Teva Pharmaceuticals, 2009).
Bicalutamide has a very small risk of causing life-threatening injury to the lungs. Bicalutamide should be stopped immediately and medical attention should be sought if serious trouble breathing develops (Teva Pharmaceuticals, 2009).
Interactions
Most people do not need to take multiple antiandrogens at once.
Bicalutamide has minimal interactions with other drugs, but care should be taken when combining bicalutamide with certain types of blood thinners such as warfarin as bicalutamide may alter their efficacy. (Wellington & Keam, 2006; Kolvenbag & Blackledge, 1996; Konishi et al., 2019)
Other information
Bicalutamide is often confused with the older and more dangerous drug flutamide. While bicalutamide is safer than flutamide, it still carries a number of noteworthy risks (Anderson, 2003).
Because bicalutamide does not stop the production of testosterone, blood tests may show testosterone levels that seem higher than expected, but have no effects on the body.
Bicalutamide is also called "Bicotexida", "Bilumiv", "Calutide", "Casodex", "Castramid", "Procalut", or simply "bica".
See also
References
- Aly. (2020). Bicalutamide and its Adoption by the Medical Community for Use in Transfeminine Hormone Therapy. Transfeminine Science. [URL]
- Anderson J. (2003). The role of antiandrogen monotherapy in the treatment of prostate cancer. BJU international, 91(5), 455–461. [DOI:10.1046/j.1464-410x.2003.04026.x]
- Cockshott I. D. (2004). Bicalutamide: clinical pharmacokinetics and metabolism. Clinical pharmacokinetics, 43(13), 855–878. [DOI:10.2165/00003088-200443130-00003]
- Kolvenbag, G. J., & Blackledge, G. R. (1996). Worldwide activity and safety of bicalutamide: a summary review. Urology, 47(1A Suppl), 70–84. [DOI:10.1016/s0090-4295(96)80012-4 ]
- Singh, S. M., Gauthier, S., & Labrie, F. (2000). Androgen receptor antagonists (antiandrogens): structure-activity relationships. Current medicinal chemistry, 7(2), 211–247. [DOI:10.2174/0929867003375371]
- Teva Pharmaceuticals. (2009). Bicalutamide: Highlights of prescribing information. [PDF]
- Wellington, K., & Keam, S. J. (2006). Bicalutamide 150mg: a review of its use in the treatment of locally advanced prostate cancer. Drugs, 66(6), 837–850. [DOI:10.2165/00003495-200666060-00007]
- Konishi, Y., Terada, T., Araki, Y., & Kawaguchi, O. (2019). Extreme Elevation of the Prothrombin Time-International Normalized Ratio due to a Probable Interaction between Warfarin and Flutamide. Internal medicine (Tokyo, Japan), 58(22), 3251–3253. [DOI:10.2169/internalmedicine.2973-19]