Description

Estradiol valerate (EV), sold for use by mouth under the brand name Progynova , is an estrogen medication. It is used in hormone therapy for menopausal symptoms and low estrogen levels, hormone therapy for transgender people, and in hormonal birth control. It is also used in the treatment of prostate cancer.

Pharmacodynamic Effects

Estradiol valerate is an estradiol ester, or a prodrug of estradiol.As such, it is an estrogen, or an agonist of the estrogen receptors.The affinity of estradiol valerate for the estrogen receptor is approximately 50 times lower than that of estradiol. In addition, estradiol valerate is rapidly cleaved into estradiol and is unable to reach target tissues in concentrations of significance, if at all. As such, estradiol valerate is essentially inactive in terms of estrogenic effect itself, acting solely as a prodrug to estradiol. The molecular weight of estradiol valerate is about 131% of that of estradiol due to the presence of its C17β valerate ester, and hence estradiol valerate contains about 76% of the amount of estradiol of an equal dose of estradiol. Aside from dose adjustment to account for the difference in molecular weight, oral estradiol valerate is considered to be equivalent to oral estradiol. Because estradiol valerate is a prodrug of estradiol, it is considered to be a natural and bioidentical form of estrogen.1

Pharmacokinetics

Regardless of the route of administration, estradiol valerate behaves as a prodrug of estradiol via cleavage by esterases into estradiol and the natural fatty acid valeric acid. This cleavage occurs not only in the liver, but also in the blood and in tissues, and the hydrolysis of estradiol valerate into estradiol and valeric acid is complete regardless of whether the medication is administered orally or parenterally. High levels of circulating estradiol are found after an intravenous injection of estradiol valerate, and this indicates very rapid cleavage of the medication upon entering circulation.

Dosage and Administration

A dosage of 1 mg/day oral estradiol valerate has been found to produce approximate circulating concentrations of 50 pg/mL estradiol and 160 pg/mL estrone, while a dosage of 2 mg/day results in circulating levels of 60 pg/mL estradiol and 300 pg/mL estrone.These concentrations of estradiol and estrone are comparable to those observed with 1 and 2 mg/day oral estradiol.

Reference

1. Oettel M, Schillinger E (6 December 2012). Estrogens and Antiestrogens II: Pharmacology and Clinical Application of Estrogens and Antiestrogen. Springer Science & Business Media. p. 261.