Equilin is a naturally occurring estrogen sex hormone found in horses as well as a medication. It is one of the estrogens present in the estrogen combination drug preparations known as conjugated estrogens and esterified estrogens. Technically, equilin is a steroidal phenolic estrogen built on the cyclopenta[a]phenanthrene core with a phenolic A ring and an extended conjugated double bond system relative to human estrone; it acts as an estrogen receptor agonist at ER alpha and ER beta, is metabolized in the liver primarily via sulfation and glucuronidation, and is supplied for pharmaceutical use typically as the water soluble sulfate salt or as part of standardized conjugated estrogen mixtures. Analytical characterization is performed by chromatographic and spectrometric methods including HPLC-UV, LC-MS and NMR for identity, purity and assay.
Parent: Estradiol / Equilin
Parent: Equilenin / Estradiol
Parent: Equilenin / Estradiol
In commercially produced conjugated equine estrogen mixtures equilin sulfate is one of several major estrogenic sulfates and is typically present as a substantial fraction of the total sulfate pool, while related equine estrogens such as equilenin, 17alpha-dihydroequilin, 17beta-dihydroequilin and various estrone and estradiol sulfates occur at lower percentages that vary by source and batch; as a general guide equilin sulfate is commonly observed in the 20 to 30 percent range of total estrogenic sulfates in conjugated preparations, related single minor components are often in the low single-digit to low double-digit percent range, and for active pharmaceutical ingredient control typical analytical specification limits for individual specified related compounds are commonly set at about 0.5 to 1.0 percent with total impurities controlled to the low single digit percent range depending on the regulatory monograph and manufacturing route. Quantitation and impurity profiling are routinely done using validated HPLC or LC-MS methods with reference standards.
Equilin is used as one component of conjugated estrogen therapies for estrogen replacement and symptomatic treatment of menopausal conditions; in pharmaceutical products it is supplied mainly as the sulfate salt or as part of standardized conjugated estrogen mixtures and contributes to the overall estrogenic activity.
Equilin is a steroidal estrogen with the four fused-ring cyclopenta[a]phenanthrene framework and a phenolic A ring; it differs from human estrone by additional conjugation in the B and C ring region, which modifies its electronic properties, receptor interactions and metabolic pathways.
Equilenin is commonly designated chemically as 3-hydroxyestra-1,3,5(10),8-tetraen-17-one, a closely related naturally occurring equine estrogen.
Sodium equilin sulfate is the sodium salt of the equilin 3-sulfate ester; the sulfate salt form increases aqueous solubility and is the form most often present and quantified in pharmaceutical conjugated estrogen preparations.
