Depending on your pathway, you may have more or fewer options. For AFAB people only GnRH analogues are suitable. For anyone AMAB, a wider range of antiandrogens are available. These antiandrogens only block the action of testosterone, so aren't appropriate for someone who's trying to block the action of oestrogen.
GnRH analogues
GnRH analogues can be used to block the action of either testosterone or oestrogen, so are suitable for anyone looking for a hormone blocker.
Leuprorelin (Prostap, Enanton, Lucrin)
- Costs £270-£300 a month.
- This is administered as either an intramuscular or subcutaneous injection every 4 to 12 weeks.
- It works by suppressing the production of the hormone GnRH, which results in the suppression of the production of oestrogen and testosterone.
- It has been established as safe and well-tolerated, with very few side effects.
Triptorelin (Decapeptyl, Gonapeptyl, Pamorelin)
- Costs £270-£300 a month.
- This is administered as an intramuscular injection every 10 to 14 weeks.
- It works by suppressing the production of the hormone GnRH, which results in the suppression of the production of oestrogen and testosterone.
- It has been established as safe and well-tolerated, with very few side effects.
Nafarelin (Synarel)
- Costs £70-£100 a month.
- This is administered as a nasal spray that is taken twice a day.
- It works by suppressing the production of the hormone GnRH, which results in the suppression of the production of oestrogen and testosterone.
- It has been established as safe and well-tolerated, with very few side effects.
5-alpha-reductase inhibitors
Finasteride
- Costs around £10 a month.
- This is a tablet that is taken daily.
- It works by blocking the enzyme 5-alpha-reductase, which results in the suppression of the conversion of testosterone to its most potent form dihydrotestosterone.
- It has been established as safe and well-tolerated, with very few side effects.
- It is less potent than other antiandrogen medications, so it can take longer to make noticeable changes.
Mechanism
Finasteride works by inhibiting the enzyme 5-alpha-reductase, which is responsible for converting testosterone into its more potent form, dihydrotestosterone (DHT). By blocking this conversion, Finasteride reduces the levels of DHT in the body.
Dutasteride
- This is a tablet that is taken daily.
- It works by blocking the enzyme 5-alpha-reductase, which results in the suppression of the conversion of testosterone to its most potent form dihydrotestosterone.
- It has been established as safe and well-tolerated, with very few side effects.
Other antiandrogens
Spironolactone
- Costs around £10 a month.
- This is a tablet that is taken daily.
- It works through a variety of mechanisms, including decreasing testosterone levels and stimulating oestrogen receptors.
- Most people who take spironolactone tolerate it well, but spironolactone does have recognised side effects, including low blood pressure (hypotension) and high potassium levels (hyperkalaemia).
- Spironolactone requires monitoring of blood pressure and blood tests to check the potassium level every 3 to 6 months.
- Spironolactone is not recommended in people with low blood pressure, high potassium levels, or kidney impairment.
- It can cause frequent urination.
Cyproterone acetate (Androcur®)
- Costs around £21 a month.
- This is a tablet that is taken daily.
- A powerful antiandrogen that suppresses the production of testosterone and blocks testosterone receptors.
- The majority of people who take cyproterone acetate tolerate it well, but cyproterone acetate can be associated with:
- Liver impairment
- Meningioma (a benign tumour of the lining of the brain)
- Cyproterone acetate requires blood tests to check the liver enzymes before starting and every 3 to 6 months.
- Cyproterone acetate is not recommended in people with evidence of liver impairment.