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Anti-androgen (steroidal) Pregnancy: The Cyprostat 50 mg SPC gives no pregnancy information (§4.6 reads only "Not applicable"); the product is licensed for patients with prostatic cancer (§4.1). Fertility: inhibition of spermatogenesis is very common and infertility is usual (§4.8).

Cyproterone acetate

Brand names: Cyprostat, Androcur

Cyproterone acetate is a steroidal anti-androgen with progestogenic activity, used in prostate cancer, to suppress the testosterone 'flare' with GnRH analogues, and for severe hypersexuality. The overview context here is its anti-androgen use in urology.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Prostatic cancer, long-term palliative treatment (where LHRH analogues or surgery are contraindicated, not tolerated, or oral therapy is preferred): 200–300 mg/day. Suppression of "flare" with initial LHRH analogue therapy: two 50 mg tablets twice daily (200 mg a day) alone for 5–7 days, then two 50 mg tablets twice daily (200 mg a day) for 3–4 weeks together with the LHRH analogue. Hot flushes in patients on LHRH analogues or after orchidectomy: 50 mg starting dose, titrated upward if necessary within 50–150 mg/day.
Route: Oral
Frequency: Long-term palliative treatment and flare suppression: daily dose divided into 2–3 doses. Hot flushes: daily dose divided into 1–3 doses. Take with some liquid after meals.
Max: 300 mg per day (the SPC's maximum daily dose)
UK SPC for Cyprostat 50 mg tablets, §4.1–4.2. Licensed for prostatic cancer only: to suppress "flare" with initial LHRH analogue therapy; for long-term palliative treatment where LHRH analogues or surgery are contraindicated, not tolerated, or oral therapy is preferred; and for hot flushes in patients on LHRH analogues or after orchidectomy. For flare suppression, give the LHRH analogue at the dose in its own SPC. Male children and adolescents: not recommended below 18 years of age (no safety or efficacy data) and must not be given before the conclusion of puberty. Elderly: no data suggesting a need for dose adjustment. Liver: contraindicated in liver disease; hepatotoxicity is dose-related and fatal cases have been reported at dosages of 100 mg and above, so check liver function before and regularly during treatment. Meningioma risk rises with cumulative dose (reported mainly at doses of 25 mg and above); stop permanently if a meningioma is diagnosed. Each tablet contains 108.75 mg lactose.

Dose adjustments

Renal

No data suggesting a need for dose adjustment in renal impairment; use in renal impairment has not been investigated (SPC §4.2).

Hepatic

Contraindicated in liver disease (SPC §4.2, §4.3). Direct hepatic toxicity (jaundice, hepatitis, hepatic failure) has been observed; it is dose-related, usually develops several months after treatment starts, and fatal cases have been reported at dosages of 100 mg and above, mostly in men with advanced prostatic cancer (§4.4).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Meningioma or a history of meningioma
  • Liver diseases (including Dubin-Johnson syndrome and Rotor syndrome)
  • Malignant tumours, except carcinoma of the prostate
  • Previous or existing liver tumours (unless due to metastases from carcinoma of the prostate)
  • Wasting diseases (except inoperable carcinoma of the prostate)
  • Existing thrombosis or embolism
  • Hypersensitivity to the active substance or to any of the excipients

Side effects

  • Very common: decreased libido, erectile dysfunction, reduced sexual drive and inhibition of gonadal function (reversible after stopping)
  • Very common: inhibition of spermatogenesis — reduced sperm count and ejaculate volume; infertility is usual
  • Common: direct hepatic toxicity, including jaundice, hepatitis and hepatic failure (fatal cases reported at dosages of 100 mg and above)
  • Common: changes in bodyweight during long-term treatment (chiefly weight gain with fluid retention)
  • Common: depressive moods and restlessness (temporary)
  • Common: dyspnoea
  • Uncommon: rash
  • Rare: meningioma (single and multiple)
  • Rare: hypersensitivity reactions
  • Very rare: benign and malignant liver tumours, which may lead to life-threatening intra-abdominal haemorrhage
  • Not known: anaemia during long-term treatment
  • Not known: suppression of adrenocortical function
  • Not known: thromboembolic events (a causal relationship has not been established)
  • Not known: dry skin from reduced sebum production; transient patchy loss and reduced growth of body hair, increased growth of scalp hair, lightening of hair colour and female-type pubic hair growth
  • Not known: osteoporosis (from long-term androgen deprivation)

Interactions

  • Strong CYP3A4 inhibitors (e.g. ketoconazole, itraconazole, clotrimazole, ritonavir) are expected to inhibit cyproterone acetate metabolism
  • CYP3A4 inducers (e.g. rifampicin, phenytoin, St John's wort) may reduce cyproterone acetate levels
  • Statins metabolised mainly by CYP3A4: the risk of myopathy or rhabdomyolysis may be increased with high cyproterone acetate doses
  • Pioglitazone and rosiglitazone: at 100 mg three times daily, cyproterone acetate may inhibit CYP2C8 and raise their levels; dose adjustment may be needed
  • Insulin and oral antidiabetics: requirements can change, because cyproterone acetate can influence carbohydrate metabolism

Monitoring

  • Liver function tests before treatment, regularly during treatment, and whenever symptoms or signs suggest hepatotoxicity; if hepatotoxicity is confirmed, withdraw unless another cause (e.g. metastatic disease) explains it and the benefit outweighs the risk
  • Consider a liver tumour if severe upper abdominal complaints, liver enlargement or signs of intra-abdominal haemorrhage occur
  • Monitor for meningioma in line with clinical practice; if one is diagnosed, stop all cyproterone-containing products permanently
  • Check adrenocortical function regularly during treatment
  • Check the red blood cell count regularly (anaemia has been reported in long-term treatment)
  • Diabetes: examine carbohydrate-metabolism parameters before and regularly during treatment; antidiabetic requirements can change
  • Severe chronic depression: monitor closely for deterioration and advise patients to report worsening at once
  • Previous arterial or venous thrombotic or thromboembolic events (e.g. deep vein thrombosis, pulmonary embolism, myocardial infarction), a history of cerebrovascular accident, or advanced malignancy: increased risk of further thromboembolic events, and may be at risk of recurrence of the disease during treatment
  • History of thromboembolic processes, sickle-cell anaemia or severe diabetes with vascular changes: consider the risk:benefit ratio carefully in each case before prescribing

Clinical monograph

How it works

It blocks androgen receptors and also suppresses gonadotrophin release, thereby lowering testosterone and reducing androgenic stimulation of prostatic tissue.

Prescribing in practice

  • Dose- and duration-dependent hepatotoxicity, including fatal hepatic failure, can occur, so liver function must be monitored and treatment stopped if significant abnormality develops.
  • A risk of meningioma has been identified, particularly with prolonged higher-dose use, prompting MHRA advice to use the lowest effective exposure and review the need for treatment.
  • It can impair adrenocortical function and cause thromboembolism, so caution is needed in cardiovascular and diabetic patients per the SPC.

Monitoring

Monitor liver function and blood counts periodically, assess adrenal function where relevant, and remain alert to neurological symptoms suggesting meningioma.

Counselling the patient

  • Report jaundice, dark urine, or persistent abdominal discomfort without delay.
  • Tell your doctor about new or worsening headaches, visual changes, or seizures.
  • Tiredness and reduced libido are expected effects of treatment.

Evidence & guidelines

Long-used anti-androgen in prostate cancer and hypersexuality, with regulatory safety reviews refining its dosing because of hepatic and meningioma risks.

Reference: NICE NG131; MHRA Drug Safety Update; BAD; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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