Polyestradiol Phosphate
Estradurin
Half-life
70 days
Time to Peak
14 days
Steady State
~350 days
Dose Range
80–320 mg
Frequency
Every 4 weeks
Overview
Ultra-long-acting depot estrogen injection. A polymer of estradiol linked by phosphate groups (NOT a simple ester). Slowly hydrolyzed over weeks to months, producing very stable E2 levels with no peaks or troughs. Originally developed for prostate cancer treatment; adopted by transfem community in Nordic countries.
Mechanism of Action
Phosphate-linked estradiol polymer is slowly hydrolyzed in vivo by phosphatases, releasing free estradiol over an extended period. Provides sustained estrogen levels.
Dosing Information
| Route | Dose Range | Half-life | Tmax | Frequency |
|---|---|---|---|---|
| Intramuscular (IM) | 80–320 mg | 70 days | 14 days | Every 4 weeks |
Storage & Handling
Room temperature — Aqueous suspension. Limited availability — primarily Nordic countries (Sweden, Finland). Not available in US, UK, or most countries. Discontinued in some markets.
Used in Regimens
Polyestradiol Phosphate is not currently part of any catalog regimen.
Data Sources
- Peer-reviewed Henriksson et al. 1999 — Polyestradiol phosphate pharmacokinetics in prostate cancer patients
- Peer-reviewed Dicker et al. 1990 — Polyestradiol phosphate dosing in prostate cancer
Related Tools
Track Polyestradiol Phosphate with Doseline
Reminders, medication level charts, injection site rotation, and protocol tracking — all free, all private.
Join the waitlistDoseline provides informational tools only. It is not a medical device and does not provide medical advice. Always consult a qualified healthcare provider.