Cyproterone Acetate

Androcur

Anti-Androgen HRT Oral FDA/EMA Label

Half-life

2.3 days

Time to Peak

3 hr

Steady State

~12 days

Bioavailability

100%

Dose Range

10–50 mg

Frequency

Daily

Overview

Potent steroidal anti-androgen and progestogen. Widely used for transfem HRT outside the US. Modern evidence supports 10-12.5 mg/day (previously 50-100 mg/day was standard). WARNING: Doses >25 mg/day are associated with dose-dependent meningioma risk with long-term use. Also carries hepatotoxicity risk -- monitor ALT/AST regularly.

Mechanism of Action

Triple mechanism: androgen receptor antagonist, potent progestogen (suppresses LH/FSH via negative feedback), and mild glucocorticoid activity. Far more potent at suppressing testosterone than spironolactone.

Dosing Information

Route	Dose Range	Half-life	Tmax	Frequency
Oral	10–50 mg	2.3 days	3 hr	Daily

Used in Regimens

1 regimen

EV + CPA (European Pathway)

Estradiol valerate injections with low-dose cyproterone acetate (CPA) anti-androgen. Standard in Germany, Netherlands, and much of Europe. CPA at low dose (6.25–12.5mg/day alternate days) provides potent androgen suppression with significantly lower meningioma risk than legacy high doses.

Low-dose CPA 6.25–12.5mg/day alternate days.

hrt_fem

Ancillary

Data Sources

EMA SPC Androcur (cyproterone acetate) EMA Summary of Product Characteristics
Peer-reviewed Transfeminine Science: Low-Dose Cyproterone Acetate Review

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