Siterone (Cyproterone Acetate 100mg) Tablets

Siterone general information

What is Siterone used for?

Siterone tablets 100mg are used to treat inoperable prostate cancer (carcinoma of the prostate), a tumour that is dependent on androgens (male hormones like testosterone) to grow.  Siterone tablets 100mg are also used to control libido in severe hypersexuality and/or sexual deviation in adult males to reduce sex drive and to reduce sexual aggression in sex offenders.  In women with severe signs of androgenisation (overproduction of androgen), Siterone tablets 100 mg are used to treat hirsutism (unwanted hair), androgenic alopecia (hair loss) and acne, which are symptoms of excess androgen production.  Siterone 100mg can also be used, in conjunction with oestrogen supplements as part of the feminisation process for male to female transsexuals.  

How does Siterone work?

Siterone tablets 100mg contain cyproterone, which is an anti-androgen that blocks the biological effects of androgens, like the male hormone testosterone, on cells containing androgen receptors.  Prostate cancer is an androgen-dependent tumour, which means that it needs testosterone to grow.  Cyproterone in Siterone 100mg binds to the androgen receptors on the tumour cells blocking the action of testosterone, which then cannot bind to the cells and stimulate the tumour cells to grow, thereby protecting the prostate from the effect of androgens and preventing further tumour growth.  Siterone tablets 100mg block the effects of androgen on other cells with andogen receptors, such as reducing the production of male hormones in the testes, which reduces aggression and increased sex drive (hypersexuality), caused by over-production of testosterone.  Women also produce some androgen but in much smaller amounts.  However, some women produce too much testosterone and this can cause hirsutism (unwanted hair), acne and/or seborrhoea (greasy skin from too much sebum) and androgen-dependent alopecia.  Siterone tablets 100mg inhibits testosterone production in these women, reducing these unwanted effects.  Blocking the effects of androgens is also a means of promoting feminisation in transgender hormone therapy for male to female transsexuals.  

What does Siterone contain?

Siterone 100 mg tablets contain the active ingredient cyproterone acetate, which is an antiandrogen and blocks the biological effects of androgens like testosterone.  They also contain lactose maize starch, povidone, colloidal silicon dioxide, magnesium stearate, purified water, pregelatinised starch (starch 1500).

Treating prostate cancer with Siterone

Siterone tablets 100 mg contain cyproterone, an anti-androgen that blocks the biological effects of androgens like testosterone.  Prostate cancer (prostatic carcinoma) is an androgen-dependent tumour of the prostate gland, which means that it needs testosterone to grow.  Cyproterone in Siterone tablets 100mg binds to the androgen receptors on the tumour cells blocking the action of testosterone and its metabolite dihydrotestosterone (DHT), which then cannot bind to the prostate cells and stimulate the tumour cells to grow.  Therefore, cyproterone in Siterone tablets 100 mg protects the prostate from the effect of androgens and cause the tumour to stop growing and to shrink.  Prostatic carcinoma cell growth is still inhibited by Siterone, even when they have spread to other parts of the body (metastasised), so that Siterone tablets 100 mg can help prevent the spread of the tumour, although they cannot cure the tumour. 

Siterone for feminising hormone therapy

Siterone tablets 100 mg contain cyproterone, an antiandrogen that blocks the biological effects of androgens like testosterone.  The feminisation process for male to female transsexuals involves achieving female characteristics as well as losing male attributes.  Cyproterone works by reducing the production of male hormones in the testes and blocking the action of testosterone, like inducing body hair and beard growth so that Siterone 100 mg can be used as the anti-androgen component of feminising hormone therapy.

What are the side effects of Siterone?

The most commonly reported side effects when taking Siterone tablets 100mg include, in men breast tenderness, breast pain (gynaecomastia), decreased libido, erectile dysfunction, reduced sexual drive, inhibition of sperm production leading to temporary infertility.  In women ovulation is inhibited and there may be some breast discomfort.  Other side effects include fatigue, tiredness and diminished vitality, breathlessness, temporary inner restlessness or depressive moods, sweating, and changes in body weight. 

When should Siterone not be used?

You should not use Siterone tablets 100mg if you:

• are allergic to cyproterone or any ingredients in Siterone
• are pregnant or are breastfeeding
• have liver disease or jaundice
• have a meningioma (brain tumrour) or other malignant tumours other than prostate cancer
• have deep venous thrombosis, thromboembolic disorders or cerebral vascular accident
• are a diabetic taking antidiabetics or insulin, without discussion with your doctor, as Siterone may affect your glucose tolerance

How should Siterone be taken?

You should take your Siterone tablets 100mg swallowed whole with a glass of water and after food.  The dose you take and how often depends on what you are being treated for and the recommendations of your doctor, which may be once or twice a day, even three times daily, and may be for several days or weeks in men.  Women should take 1 or 2 tablets a day at the same time each day, for the first 21 days of the menstrual cycle, followed by 7 tablet-free days, to allow withdrawal bleeding to occur.  You should continue to take your Siterone tablets 100 mg for as long as recommended by your doctor, which may be for several weeks, depending on what you are being treated for.

How long should you take Siterone?

You should continue to take your Siterone tablets 100mg for as long as recommended by your doctor, which may be for several weeks, depending on what you are being treated for.

Missed dose of Siterone

If you miss a dose of Siterone tablets 100mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Siterone be stored?

You should store your Siterone tablets 100mg below 25°C in a cool dry place and protected from light.