Bicalutamide
Overview
Bicalutamide is a non-steroidal androgen receptor blocker. Unlike spironolactone or CPA, it does not lower testosterone levels — instead, it blocks testosterone from binding to androgen receptors throughout the body.
| Property | Details |
|---|---|
| Drug class | Non-steroidal androgen receptor antagonist |
| Mechanism | Competitively binds androgen receptors, blocking T and DHT |
| Half-life | 5–7 days (very long) |
| Typical dose | 25–50 mg/day |
| Frequency | Once daily |
How It Works
Bicalutamide binds to androgen receptors with high affinity, preventing testosterone and DHT from activating them. Because it does not suppress testosterone production, your total T levels may actually rise (the body compensates by producing more), but the testosterone cannot bind to receptors and therefore has no masculinising effect.
Dosing
| Level | Dose | Notes |
|---|---|---|
| Starting | 25 mg/day | May be sufficient for many |
| Typical | 50 mg/day | Most common dose |
| High | 50 mg/day | Exceeding 50 mg increases hepatotoxicity risk without clear additional benefit |
Pros
| Benefit | Details |
|---|---|
| Low side effect burden | No diuretic effects, no potassium issues |
| No hyperkalemia risk | Safe with ACE inhibitors / NSAIDs |
| Once-daily dosing | Long half-life allows convenient dosing |
| Effective for hair preservation | Particularly good for scalp hair |
| Good for those who can't tolerate spiro | Low hassle alternative |
| Does not cause depression | Unlike CPA in some people |
Side Effects
| Side Effect | Frequency | Notes |
|---|---|---|
| Breast tenderness | Common | Expected androgen blockade effect |
| Hot flashes | Some | Due to high free T levels |
| Fatigue | Occasional | Usually resolves |
| Mild liver enzyme elevation | Monitor | Generally not clinically significant |
| Hepatotoxicity | Rare | Requires liver monitoring |
Liver Function Monitoring
Bicalutamide carries a small risk of hepatotoxicity (liver injury). While rare at HRT doses, adhere to the following monitoring schedule:
| Time | Test | Action |
|---|---|---|
| Baseline | ALT, AST | Establish baseline |
| 1 month | ALT, AST | Early detection of rare reaction |
| 3 months | ALT, AST | Confirm safety |
| 6 months | ALT, AST | Ongoing monitoring |
| Annually | ALT, AST | Long-term safety |
If you develop jaundice (yellow skin/eyes), dark urine, or severe fatigue, stop bicalutamide and seek medical attention immediately.
Comparison
| Aspect | Bicalutamide | Spironolactone | CPA |
|---|---|---|---|
| Receptor blocker? | Yes (strong) | Yes (weak) | No (progestogen) |
| Lowers T? | No (may raise) | Mildly | Yes (strongly) |
| Liver risk | Rare | No | Possible |
| Meningioma risk | No | No | Yes |
| Potassium issues | No | Yes | No |
| Half-life | 5–7 days | 1.4 hours | 38 hours |
Who Should Consider Bicalutamide
- People who get side effects from spironolactone
- Those who cannot take CPA (meningioma risk, depression)
- People on medications that interact with spironolactone
- Those who want minimal side effects
References
Bocchinfuso WP, Korach KS (1997). Bicalutamide: a nonsteroidal androgen receptor antagonist.
UCSF Transgender Care. Anti-androgens. https://transcare.ucsf.edu/guidelines
WPATH (2022). Standards of Care, Version 8. https://www.tandfonline.com/doi/full/10.1080/26895269.2022.2100644