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drug-monograph
cyproterone
Other Names
Generic brand(s) available, Androcur®, Androcur Depot®
Appearance
Tablets- white to faintly yellow; Injectable- liquid for injection
Funding Program
ODB - General Benefit
A - Drug Name
cyproterone
SYNONYM(S): SH714; CyPat
COMMON TRADE NAME(S): Androcur® (); Androcur Depot® ()
B - Mechanism of Action and Pharmacokinetics
Cyproterone is a steroidal antiandrogen with weak progestational activity. It blocks androgen binding to the androgen receptor as well as progestational activity, which results in the partial suppression of pituitary gonadotropin, and a decrease in serum testosterone. Treatment with cyproterone alone results in incomplete suppression of serum testosterone levels. Meta-analyses of studies comparing castration vs. cyproterone plus castration suggest that outcomes are superior with castration alone.
Absorption
| Bioavailability | Oral absorption complete (at 50mg dose) |
Distribution
Tissue distribution is one of the major causes of the rapid fall of plasma levels.
| Cross blood brain barrier? | No information found |
| Volume of distribution | No information found |
| PPB | No information found |
Metabolism
The principal metabolite is 15 ß-hydroxy-cyproterone acetate.
| Active metabolites | No information found |
| Inactive metabolites | yes |
Elimination
Drug is excreted unchanged in urine (unconjugated) and feces (glucuronidized).
| Feces | 60 % |
| Urine | 33 % |
| Clearance | no information found |
| Half-life | 38 ± 5 hours (oral route) |
C - Indications and Status
Health Canada Approvals:
- Palliative treatment of advanced prostate cancer
D - Adverse Effects
Emetogenic Potential:
Not applicable
Extravasation Potential: Not applicable
| ORGAN SITE | SIDE EFFECT* (%) | ONSET** | |||
|---|---|---|---|---|---|
| Cardiovascular | Arterial thromboembolism | E | |||
| Heart failure | E | ||||
| Hypotension | I | ||||
| Myocardial infarction (acute) | E | ||||
| Other (Pulmonary fat microemboli) | I | ||||
| Tachycardia | I | ||||
| Venous thromboembolism | E | ||||
| Dermatological | Alopecia (mild) | D | |||
| Dry skin | D | ||||
| Hirsutism | D | ||||
| Photosensitivity | E | ||||
| Pruritus | D | ||||
| Rash (may be severe) | E | ||||
| Gastrointestinal | Anorexia | I E | |||
| Constipation | E | ||||
| Diarrhea | E | ||||
| Dyspepsia | E | ||||
| Glossitis | E | ||||
| Nausea | I E | ||||
| Vomiting | I E | ||||
| Weight changes | E | ||||
| General | Edema | E | |||
| Fatigue (or weakness) | E | ||||
| Hematological | Hemolysis (rare) | E | |||
| Leukocytosis | E | ||||
| Myelosuppression (rare) | E | ||||
| Hepatobiliary | Hepatic failure | E D | |||
| Hepatitis (acute) | E D | ||||
| ↑ LFTs | E | ||||
| Pancreatitis | E | ||||
| Hypersensitivity | Drug reaction (including chills; rare) | I | |||
| Metabolic / Endocrine | Blood corticotrophin decreased (or decreased cortisol - with high dose) | E | |||
| ↑ Ca | E | ||||
| Glucose intolerance (impaired carbohydrate metabolism / diabetes) | E | ||||
| Hyperlipidemia (or other changes in lipid profiles) | E | ||||
| ↑ Na | E | ||||
| Musculoskeletal | Osteoporosis | D | |||
| Neoplastic | Other (benign liver tumours) | D L | |||
| Secondary malignancy (hepatoma, bladder cancer, meningiomas) | D L | ||||
| Nervous System | Depression | D | |||
| Dizziness | D | ||||
| Encephalopathy (rare) | D | ||||
| Headache | E | ||||
| Syncope | E | ||||
| Ophthalmic | Eye disorders (abnormal vision) | D | |||
| Optic nerve disorder | D | ||||
| Renal | Renal failure | E | |||
| Reproductive and breast disorders | Erectile dysfunction (common) | E | |||
| Gynecomastia | E | ||||
| Infertility (reversible) | D | ||||
| Lactation disorder (galactorrhea) | E | ||||
| ↓ Libido (common) | E | ||||
| Other (breast nodules) | E | ||||
| Respiratory | Cough, dyspnea | E D | |||
| Pulmonary fibrosis | E D | ||||
| Vascular | Hot flashes | D | |||
* "Incidence" may refer to an absolute value or the higher value from a reported range.
"Rare" may refer to events with < 1% incidence, reported in post-marketing, phase 1 studies,
isolated data or anecdotal reports.
Dose-limiting side effects are underlined.
** I = immediate (onset in hours to days) E = early (days to weeks)
D = delayed (weeks to months) L = late (months to years)
Side effects are rarely of sufficient severity to require dosage reduction or treatment discontinuation. The most common side effects are hormonal with changes in libido, breast tenderness, gynecomastia, azoospermia and impotence, which are reversible.
Hepatotoxicity, including liver failure, has been reported especially after several months of use and appears to be dose-related. Benign or malignant hepatic tumours may occur and lead to intrabdominal bleeding.
Decreased response to ACTH and lowered cortisol levels have been reported. Adrenocortical function tests should be monitored by serum cortisol assay.
Impairment of carbohydrate metabolism may occur. Diabetic patients should be monitored closely.
A negative nitrogen balance occurs at the start of therapy, but generally corrects itself within 3 months of continued therapy.
When cyproterone is used alone it has a minor effect on blood clotting factors; the risk is increased when used in combination with estrogens. Cyproterone should be discontinued at the first sign of thrombophlebitis or thromboembolism, and the patient should be carefully re-evaluated if manifestations of thrombotic disorders occur.
Antiandrogen withdrawal syndrome may occur. After discontinuation for disease progression, 6-8 weeks should elapse before making further treatment decisions.
E - Dosing
Refer to protocol by which patient is being treated. Some protocols combine cyproterone with diethylstilbestrol or other agents.
Adults:
Oral:
- 100 mg bid or tid (total of 200-300mg/day)
- Post-orchiectomy: 50-100mg bid (total of 100-200 mg/day)
Intramuscular:
- Q1W: 300 mg (Depot injection)
- Post-orchiectomy: 300 mg q2w
Dosage with Toxicity:
Discontinue: Arterial or venous thromboembolism, meningioma, hepatotoxicity
Dosage with myelosuppression: No adjustment required
Dosage with Hepatic Impairment:
Contraindicated. Discontinue immediately if drug-related hepatic toxicity occurs.
Dosage with Renal Impairment:
Excreted in urine - use with caution with mild impairment and do not use with moderate or severe impairment.
Children:
Do not use in children.
F - Administration Guidelines
- Drug available by outpatient prescription.
- Avoid alcohol intake during treatment.
- Tablets: Oral self-administration; take after meals.
G - Special Precautions
Other:
Cyproterone is contraindicated in patients with hypersensitivity to the drug, active liver disease, and with hepatic or renal impairment, Dubin Johnson syndrome, Rotor syndrome, previous or existing liver tumours (not due to prostate carcinoma metastases), presence/history of meningioma, wasting disease (except for inoperable prostate carcinoma), severe chronic depression, or existing thromboembolic process. The concomitant use of alcohol should be avoided. Patients with depression should be watched carefully as symptoms may worsen during the first 6-8 weeks of treatment. Hepatic impairment resulting in fatal hepatic failure has been reported; patients should be carefully assessed.
Use with caution in patients with cardiac disease or patients with a history of thromboembolism. Exercise special care when driving or operating machinery as marked fatigue and weakness are common, especially early in treatment.
The mutagenic and carcinogenic potential of prolonged cyproterone use is not known but fetal abnormalities have been reported; production of abnormal sperm during therapy has been observed. Adequate contraception should be used by both sexes during cyproterone treatment and for at least 6 months after treatment cessation. Although cyproterone is contraindicated in women, it does cross the placenta, and exposed patients should not breastfeed.
H - Interactions
| AGENT | EFFECT | MECHANISM | MANAGEMENT |
|---|---|---|---|
| alcohol | Theoretical possibility of reduced tumour control | Reduced anti-androgenic effect | Avoid, manufacturer recommends against use of alcohol. |
| Ethinyl estradiol | Thrombosis | ↑ coagulation capability | Monitor |
| CYP3A4 inhibitors (i.e. ketoconazole, voriconazole, clarithromycin, ritonavir, fruit or juice from grapefruit, Seville oranges, starfruit or pomegranate ) | ↑ cyproterone levels | ↓ metabolism of cyproterone | Caution |
| CYP3A4 inducers (i.e. phenytoin, rifampin, dexamethasone, carbamazepine, phenobarbital, St. John’s Wort, etc) | ↓ cyproterone levels | ↑ metabolism of cyproterone | Caution |
| Substrates of CYP 2C8, 2C9, 2C19, 3A4, 2D6 | ↑ levels of substrates | In vitro, cyproterone inhibits these enzymes at high daily doses (300mg/day) | Caution |
| Substrates of CYP 1A2, 2E1 | ↓ levels of substrates | In vitro, cyproterone increases activity of these enzymes | Caution |
| HMGCoA reductase inhibitors (“statins”) | ↑ risk of statin induced myopathy and rhabdomyolysis | Cyproterone uses the same metabolic pathway as statins | Caution |
I - Recommended Clinical Monitoring
Recommended Clinical Monitoring
| Monitor Type | Monitor Frequency |
|---|---|
| Liver function tests | Baseline and periodic |
| Renal function tests | Baseline and periodic |
| Clinical evaluation for mood changes, hypoadrenalism, diabetes, venous/arterial thromboembolism |
Grade toxicity using the current NCI-CTCAE (Common Terminology Criteria for Adverse Events) version
Suggested Clinical Monitoring
| Monitor Type | Monitor Frequency |
|---|---|
| CBC | periodic |
| Cortisol levels | intermittent |
| Plasma lipids in patients at risk | |
| Blood glucose in patients at risk |
K - References
Cancer Drug Manual (the Manual), 1994, British Columbia Cancer Agency (BCCA).
NCI Drug Dictionary. Accessed May 24, 2011.
Product Monograph: Androcur® and Androcur® Depot (cyproterone acetate). Bayer Inc., Feb 25, 2011.
L - Disclaimer
Refer to the New Drug Funding Program or Ontario Public Drug Programs websites for the most up-to-date public funding information.
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Last Updated: July 27, 2026
