Estradiol Benzoate
Half-life
42 hr
Time to Peak
15 hr
Steady State
~9 days
Bioavailability
100%
Dose Range
0.5–2 mg
Frequency
Every other day
Overview
Short-acting injectable estrogen ester. Historically used for menopausal HRT; still available from compounding pharmacies. Produces very high peaks and rapid decline, requiring injection every 1-3 days for stable levels. Some protocols use EB as a "loading" injection to rapidly achieve therapeutic E2 levels.
Mechanism of Action
Prodrug: benzoate ester is hydrolyzed in vivo, releasing active 17β-estradiol.
Dosing Information
| Route | Dose Range | Half-life | Tmax | Frequency |
|---|---|---|---|---|
| Intramuscular (IM) | 0.5–2 mg | 42 hr | 15 hr | Every other day, every 3 days |
Storage & Handling
Room temperature — Available from compounding pharmacies. Not widely commercially manufactured.
Used in Regimens
Estradiol Benzoate is not currently part of any catalog regimen.
Data Sources
- Peer-reviewed Oriowo et al. 1980 — Head-to-head comparison of EV and EB
- Peer-reviewed Toh et al. 1986 — Estradiol benzoate pharmacokinetics
Related Tools
Track Estradiol Benzoate with Doseline
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