Estradiol Hemihydrate is a hydrated form of 17β-estradiol, a naturally occurring estrogen hormone and an important active pharmaceutical ingredient (API) used in estrogen-containing pharmaceutical formulations.
Estradiol is the principal naturally occurring estrogen in humans and plays an important role in the development and maintenance of the female reproductive system, as well as in bone and other physiological functions. Estradiol Hemihydrate is used in pharmaceutical products where a controlled hydrated form of estradiol is specified.
Estradiol Hemihydrate is the hemihydrate form of estradiol, containing approximately one-half molecule of water of crystallization per estradiol molecule.
CAS Number: 3531-02-4
Molecular Formula: C₁₈H₂₄O₃
Molecular Weight: 272.39 g/mol
The hemihydrate form should be distinguished from anhydrous estradiol when specifying API identity, molecular weight and solid-state characteristics.
Estradiol binds to estrogen receptors (ERα and ERβ) and regulates estrogen-responsive gene expression in target tissues.
Its physiological and pharmacological effects include:
Estradiol Hemihydrate is used as an API in pharmaceutical formulations for:
The exact indication depends on the final formulation, route of administration and applicable regulatory labeling.
Estradiol Hemihydrate is a steroidal estrogen API with defined stereochemistry and a controlled hydrated solid-state form. The hemihydrate state is an important quality attribute for pharmaceutical manufacturing.
Typical quality evaluation may include:
Pharmaceutical-grade Estradiol Hemihydrate should comply with the applicable approved specification and relevant pharmacopoeial and regulatory requirements.
For a hemihydrate API, water content and solid-state form are particularly important. Depending on the approved specification, analytical methods such as Karl Fischer water determination, XRPD and thermal analysis may be used.
A qualified supplier should provide Certificate of Analysis (CoA), specification sheet, SDS/MSDS, batch traceability and applicable regulatory documentation.
Estradiol Hemihydrate should be stored in a tightly closed container, protected from excessive moisture, heat and direct light, according to the manufacturer's approved storage and stability requirements.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 10 ppm |
| pH (1% Solution) | 5.5 – 6.5 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.0% |
| Melting Point | 150°C – 154°C |