By Aly W. | First published September 22, 2018 | Last modified March 21, 2022
This is a collection of information on the topic of bicalutamide (brand name Casodex) as an antiandrogen and component of hormone therapy for transfeminine people. Transfeminine people often inquire about sources of information for bicalutamide for themselves and their medical providers so I thought it’d be helpful to have an index of this information.
Bicalutamide is a nonsteroidal antiandrogen and works by acting as a potent and selective androgen receptor antagonist. In other words, it works by directly competing with and displacing androgens like testosterone and dihydrotestosterone from their biological target and thereby blocking their actions. This is in contrast to antiandrogens that act by decreasing testosterone levels.
Bicalutamide was developed for and is most widely used in the treatment of prostate cancer, an androgen-dependent disease. However, bicalutamide is also used for other androgen-related indications. Examples of these uses include the treatment of hirsutism and scalp hair loss in cisgender women, the treatment of gonadotropin-independent early puberty in cisgender boys, and of course hormone therapy for transfeminine people.
While bicalutamide is not yet widely used in transfeminine people, it is seeing increasing adoption in this group and has advantages over conventional antiandrogens used in transfeminine people like spironolactone and cyproterone acetate in the areas of efficacy, tolerability, and safety. However, bicalutamide itself has a small risk of liver as well as lung issues and liver function should be monitored in people taking bicalutamide particularly in the first few months of treatment.
- Information on Bicalutamide (Casodex) as an Antiandrogen for Transfeminine People (Aly W., 2018)
- Published Literature on Bicalutamide as an Antiandrogen for Transfeminine People (Aly W., 2019)
- Bicalutamide: Frequently Asked Questions and Common Misconceptions (Aly W., 2018)
- Discussion on Bicalutamide Dosage in Transfeminine People (Aly W., 2019)
- Bicalutamide and its Adoption by the Medical Community for Use in Transfeminine Hormone Therapy (Aly W., 2020)
- An Introduction to Hormone Therapy for Transfeminine People (Aly W., 2018)
- An Exploration of Possibilities for Hormone Therapy in Non-Binary Transfeminine People (Aly W., 2019)
- Medical uses of bicalutamide
- Side effects of bicalutamide
- Pharmacology of bicalutamide
- Comparison of bicalutamide with other antiandrogens
- Medical uses of bicalutamide § Transgender hormone therapy
- Feminizing hormone therapy § Nonsteroidal antiandrogens
- Flutamide § Transgender hormone therapy
- Nilutamide § Transgender hormone therapy
- Medical uses of bicalutamide § Skin and hair conditions
- Bicalutamide § Research
- Flutamide § Skin and hair conditions
- Nilutamide § Skin and hair conditions
Literature excerpts on bicalutamide in transfeminine people can be found here. They are listed by date of publication, from oldest to most recent. The page contains essentially everything that exists in the published literature on the topic of bicalutamide in transfeminine people. The most major piece of literature on bicalutamide in transfeminine people at this time is the following clinical study:
- Neyman, A., Fuqua, J. S., & Eugster, E. A. (2019). Bicalutamide as an androgen blocker with secondary effect of promoting feminization in male-to-female transgender adolescents. Journal of Adolescent Health, 64(4), 544–546. [DOI:10.1016/j.jadohealth.2018.10.296]
- Casodex (bicalutamide) 50 mg FDA (US) label
- Casodex (bicalutamide) 150 mg MHRA (UK) prescribing information
- Casodex (bicalutamide) 150 mg MHRA (UK) patient leaflet (PDF)
- Casodex (bicalutamide) 50 and 150 mg MHRA (UK) public assessment report
- Bicalutamide, a new anti-androgen for trans women and girls (Zinnia Jones | Gender Analysis, 2018)
Various clinicians are known to either be using bicalutamide or to otherwise be willing to prescribe it as an antiandrogen for transfeminine people. Below is a list of these providers.
- Dr. Kristen Vierregger at Metamorphosis Medical Center (Facebook) in Buena Park, California a
- Lyle “Cac” Cook, PA-C at St. John’s Traynham in Los Angeles, California
- Dr. Howard Rice at Rice Medical Group in Mountain View, California
- Dr. John Randolph at the University of Michigan in Ann Arbor and Northville, Michigan
- Dr. William Powers at Powers Family Medicine (Facebook) in Farmington Hills, Michigan
- Dr. Michael Giffen in Fishers/Indianapolis, Indiana
- Dr. Anna Neyman at Riley Children’s Hospital in Indianapolis, Indiana
- Dr. John Fuqua at Riley Children’s Hospital in Indianapolis, Indiana
- Dr. Erica Eugster at Riley Children’s Hospital in Indianapolis, Indiana
- Dr. Justin Schweitzer at Cooper University Health Care in Cherry Hill, New Jersey
- Dr. Fatai A. Gbadamosi in Buffalo, New York
- Dr. Grace Evins at Live Well WNC (Facebook) in Asheville, North Carolina
- Dr. Negin Misaghian-Xanthos at Wilmington Health in Wilmington, North Carolina
- Dr. Jessica Brooke Huffman at 2BWell Clinic in Portland, Oregon b
- Dr. Jessica Zwiener at Braeswood Endocrinology (Facebook) in Bellaire, Texas
- Tiffany Wilson, MSN, APRN, FNP-C at Texas A&M University Student Health Services in College Station, Texas
- Dr. Rixt Luikenaar at Rebirth OB/GYN in Salt Lake City, Utah
- Dr. Crystal Beal at QueerDoc (Facebook) in Seattle, Washington (blog post) a
- Dr. Kevin Hatfield at The Polyclinic in Seattle, Washingtonc
- Dr. Andrew Smith at The Polyclinic in Seattle, Washingtonc
- Dr. Lauren Gresham at Nutima Integrative Medicine in Seattle, Washington b
a Available for telemedicine in various areas.
b It should be noted and cautioned that Dr. Huffman and Dr. Gresham are naturopathic physicians.
c Only accepting patients ≤14 years of age.
- Dr. L. Y. Louie Chan at Church Wellesley Health Centre in Toronto, Ontario, Canada
- Dr. Ada Cheung in Heidelberg, Victoria, Australia, near Melbourne, Australia, may be willing to prescribe bicalutamide (but unconfirmed)
- Dr. Jon Hayes in St Leonards, New South Wales, Australia, in/near Sydney, Australia
- Dr. Ethan Salleh at Gladstone Road Medical Centre in Highgate Hill, Queensland, Australia, near Brisbane, Australia
If you know of any other clinicians who use bicalutamide or are willing to prescribe it for transfeminine people, please let me know and I will add them to this page.
Bicalutamide has almost no side effects in women (Müderris et al., 2002; Moretti et al., 2018). However, bicalutamide produces abnormal liver function tests (a predictor of liver toxicity) in a small percentage of people and is associated rarely with liver toxicity (Wiki) and lung toxicity (Wiki). Liver and lung toxicity with bicalutamide can both potentially be fatal. There has been concern and reservation about the use of bicalutamide in transfeminine people due to these risks (Aly W., 2020). It is important that transfeminine people and clinicians be aware of these risks and engage in appropriate monitoring.
In elderly men with early-stage prostate cancer, 150 mg/day bicalutamide alone was associated with elevated liver enzymes in 3.4% of users relative to 1.9% of controls—a significant 1.5% difference attributable to bicalutamide—in a very large phase 3 randomized control trial (n ≈ 8,000 total) (Table). In elderly men with late-stage prostate cancer, 50 mg/day bicalutamide plus a gonadotropin-releasing hormone (GnRH) agonist was associated with elevated liver enzymes in 7.5% and markedly elevated liver enzymes in 0.5% in a large phase 3 randomized controlled trial (n ≈ 400 in this group) (Table). There was no placebo group in this study; instead, the comparison group was 750 mg/day flutamide in combination with a GnRH agonist. In this flutamide comparison group, elevated liver enzymes occurred in 11.3% and markedly elevated liver enzymes occurred in 2.5% (n ≈ 400 in this group as well) (Table). In cisgender women with scalp hair loss, 10 to 20 mg/day bicalutamide was used in almost all women and was associated with elevated liver enzymes in 3% of women in a large retrospective chart review (n ≈ 300) (Ferial Ismail et al., 2020). Also in cisgender women with scalp hair loss, 25 to 50 mg/day bicalutamide was associated with elevated liver enzymes in 11% of women in a smaller retrospective chart review (n ≈ 50) (Fernandez-Nieto et al., 2020).
Bicalutamide has been implicated in a number of published case reports of hepatotoxicity, some of which have been fatal (Table). Causality analysis has been performed in a subset of these case reports and has implicated bicalutamide as likely responsible. The doses correspond to those widely used clinically and ranged from 50 to 150 mg/day with no clear dose dependency. The onset of hepatotoxicity ranged from 2 days to 5 months. In addition to case reports published in the medical literature, bicalutamide has been associated with around 40 cases of liver failure—of which 25 cases resulted in death—in the United States Food and Drug Administration (FDA)’s MedWatch/FAERS database. These cases have not evaluated likelihood of causality and could in a portion of instances be coincidental however. On the other hand, fewer than 10% of serious adverse reactions are reported to the FDA, and hence the true number may be much greater (Graham, Ahmad, & Piazza-Hepp, 2002). There is an unpublished report in the transgender medical community of bicalutamide causing liver failure and death in a healthy young transgender woman (Aly W., 2020).
No cases of serious liver toxicity or liver failure occurred with bicalutamide in around 8,000 men total during clinical development of bicalutamide for early or late prostate cancer (Blackledge, 1996; Kolvenbag & Blackledge, 1996; McLeod, 1997; Anderson, 2003; Iversen et al., 2004). The risk of liver toxicity with flutamide has been estimated as 0.03% (3 in every 10,000) based on data from the FDA’s MedWatch/FAERS database, although other research has had higher estimates (Wiki). Bicalutamide is considered to have significantly less liver toxicity than flutamide.
Due to the risk of liver toxicity with bicalutamide, liver monitoring should be done regularly during bicalutamide therapy. If liver enzymes are sufficiently elevated, bicalutamide should be promptly discontinued (or possibly dosage reduced). Since most cases seem to occur early into treatment (within the first 6 months), this may be the most important time for liver monitoring.
Bicalutamide has been associated with interstitial pneumonitis, which can lead to pulmonary fibrosis, and with eosinophilic lung disease (Wiki). A number of published case reports of interstitial pneumonitis and eosinophilic lung disease in association with bicalutamide exist, with some of these cases being fatal (Table). The doses ranged from 50 to 200 mg/day and the onset ranged from 2 weeks to 6 years, but most cases occurred within the first year. A study using data from the FDA’s MedWatch/FAERS database estimated that the incidence of interstitial pneumonitis with bicalutamide was around 0.01% (1 in 10,000) (Bennett, Raisch, & Sartor, 2002). This may be an underestimate due to underreporting to the FDA and other factors however (Ahmad & Graham, 2003).