Choosing an antiandrogen

Commonly used antiandrogens in feminising hormone treatment include gonadotropin releasing hormone (GnRH) analogues (leuprorelin, triptorelin, nafarelin), 5-alpha-reductase inhibitors (finasteride, dutasteride), spironolactone, and cyproterone acetate. These work by suppressing the production or action of testosterone.

GnRH analogues

Leuprorelin (Prostap®)

This is administered as an intramuscular 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®)

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®)

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

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.

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

This is a tablet that is taken daily.

It works as an antiandrogen through a variety of mechanisms, including by decreasing testosterone levels and stimulating oestrogen receptors.

While most people who take spironolactone tolerate it well, spironolactone does have recognised side effects, including low blood pressure (hypotension) and high potassium levels (hyperkalaemia).

According, 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.

Cyproterone acetate (Androcur®)

This is a tablet that is taken daily.

It is a very powerful antiandrogen that suppresses the production of testosterone and blocks testosterone receptors.

However, while the majority of people who take cyproterone acetate tolerate it well, cyproterone acetate can be associated with some significant medical risks.

Recognised risks associated with cyproterone include liver impairment and the development of meningioma (a benign tumour of the lining of the brain).

According, cyproterone acetate requires blood tests to check the liver enzymes every 3 to 6 months.

Cyproterone acetate is not recommended in people with evidence of liver impairment.

Updated on March 20, 2024

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