Reversed-phase liquid chromatographic method for estrogen determination in equine biological samples.

The research presents a technique to quantify certain estrogens – key components in hormonal replacement therapies – produced during horse pregnancies. The method is successful and met all necessary scientific standards, indicating its potential use in studying the bioavailability and bioequivalence of these hormones.

Exploring the Context

• This research focuses on equine unsaturated estrogens – estrogenic hormones that are significant in many brand formulations used for hormonal replacement therapy in hypogonadic and postmenopausal women. Equilenin (EL), equilin (EQ), 17alpha-dihydroequilin (17dEQ), and estrone (El) are produced by the fetoplacental unit during equine pregnancy and are primarily isolated and used in these therapeutic formulations.

The Research Methodology

• The researchers developed and implemented a method for the quantitative determination of EL, EQ, 17dEQ, and El in the plasma of pregnant mares.
• Pregnant mare’s blood samples were obtained weekly through jugular venipuncture, with sodium ethylenediaminetetracetic as the anticoagulant.
• For the quantitation, the plasma subjected to enzymatic hydrolysis followed by liquid-liquid extraction.
• To analyze these hormones, the researchers used a high-performance liquid chromatographic system equipped with a UV detector set at 220 nm and an ODS Hypersil column.
• The method fulfilled precision, specificity, and accuracy requirements, rendering it scientifically valid.

Results & Implications

• The hormonal levels determined in a target mare throughout pregnancy varied: 97.91 to 449.13 for E1, 116.47 to 266.02 for EL, 74.92 to 235.54 for EQ, and 84.26 to 300.03 ng/mL for 17dEQ.
• The respective maximum levels reached occurred during the 25th, 20th, 33rd, and 27th weeks of pregnancy.
• The successful testing of these estrogens’ quantitation method in the plasma from a pregnant mare suggests the broader application of this method.
• The technique holds promise in the study of estrogen bioavailability and bioequivalence, significant fields in drug development and clinical pharmacology.