Bicalutamide, a new anti-androgen for trans women and girls

Disclaimer: I am not a doctor, and this is not medical advice. Do not take any medication without appropriate medical supervision.

Zinnia JonesPreviously I’ve looked at low-cost alternatives to GnRH analogue puberty blockers for trans adolescents, including medroxyprogesterone acetate, spironolactone, cyproterone acetate, and norethindrone. One new option for trans girls has recently been studied: bicalutamide (Casodex), an oral nonsteroidal anti-androgen used to block testosterone in cases of prostate cancer.

Bicalutamide works by directly blocking the action of androgens at the androgen receptor. It is not an antimineralocorticoid like spironolactone, a glucocorticoid and synthetic progestin like cyproterone acetate, or a DHT blocker like finasteride or dutasteride. For this reason, bicalutamide may be an option for trans women who can’t tolerate the side effects of other anti-androgens, and past publications on hormonal treatment have listed bicalutamide as having a potential role in HRT.

The newest study by a team at the Indiana University School of Medicine and Riley Hospital for Children is the first to look at bicalutamide as a puberty blocker and feminizing medication in adolescent trans girls. The authors found that bicalutamide at 50mg a day produced suppression of testosterone as well as development of breast tissue:

Results: Of 77 patients with GD identified, 29 were MTF, of whom 14 (48%) aged 15.8 ± 1.9 years (range 12-18.4yr) were treated with bicalutamide 50 mg daily between 2013 and 2017. Of these, 3 were started on estrogen concurrently whereas 11 received bicalutamide alone, 7 of whom have returned for follow up thus far. After an average of 5.7±1.5 months, 86% of the patients (n=6) had breast development consisting of Tanner stage III in 4, Tanner stage II in 1, and Tanner stage III/II of the right and left breast in 1. The 7th patient was noted to have Tanner III breasts at her 2nd follow-up clinic visit 12.5 months after starting bicalutamide. LFTs were obtained on 4 patients, estradiol on 3 patients and testosterone on 2 patients while exclusively taking bicalutamide. LFTs were unremarkable and concentrations of estradiol and testosterone were 26-61 pg/mL and 524-619 ng/dL, respectively.

Bicalutamide is available as a generic medication for less than $20 a month. Given that GnRH analogue puberty blockers can cost thousands of dollars and may not be covered by insurance, this lesser-known anti-androgen may be an economical option for adolescent trans girls. 

Support Gender Analysis on Patreon

About Zinnia Jones

My work focuses on insights to be found across transgender sociology, public health, psychiatry, history of medicine, cognitive science, the social processes of science, transgender feminism, and human rights, taking an analytic approach that intersects these many perspectives and is guided by the lived experiences of transgender people. I live in Orlando with my family, and work mainly in technical writing.
This entry was posted in Breast, Endocrinology, Trans youth, Transgender medicine and tagged , , , . Bookmark the permalink.

2 Responses to Bicalutamide, a new anti-androgen for trans women and girls

Leave a Reply

Your email address will not be published. Required fields are marked *