|DB00286||Conjugated estrogens||The conjugated estrogens are noncrystalline mixtures of purified female sex hormones obtained either by its isolation from the urine of pregnant mares or by synthetic generation from vegetal material. Both of these products are later conjugated to natrium sulfate by ester bonds in order to make them more water soluble.[L5605, T475]
The conjugated estrogen product contains a mix of estrogen from which about 50% is represented by estrone sulfate followed by 25% of equilin sulfate, 15% of 17-alpha-dehydroequilenin sulfate, 3% of equilenin sulfate, 5% of 17-alpha and 17-beta-dihydroequilenin sulfate, 2% of 17-alpha-estradiolsulfate and 3% of 17-beta-estradiolsulfate. It also presents a large number of unidentified molecules with weak estrogenic activity as well as non-human molecules when it is obtained from pregnant mares urine.[T475]
The conjugated estrogen mixture was approved for marketing in US in 1942 based on the efficacy against certain conditions. However, until 1986 official clinical trials were performed and this product was determined to be effective for the treatment of osteoporosis.[T484] The currently approved product of conjugated estrogens was developed by Wyeth Ayerst and FDA approved in 2003.[L5608]|
|DB13956||Estradiol valerate||Estradiol Valerate (also known as E2V) is a pro-drug ester of [DB00783], a naturally occurring hormone that circulates endogenously within the human body. Estradiol is the most potent form of all mammalian estrogenic steroids and acts as the major female sex hormone. As a pro-drug of estradiol, estradiol acetate therefore has the same downstream effects within the body through binding to the Estrogen Receptor (ER) including ERα and ERβ subtypes, which are located in various tissues including in the breasts, uterus, ovaries, skin, prostate, bone, fat, and brain.
[DB00783] is commonly produced with an ester side-chain as endogenous estradiol has very low oral bioavailability on its own (2-10%). First-pass metabolism by the gut and the liver quickly degrades the estradiol molecule before it gets a chance to enter systemic circulation and exert its estrogenic effects [A12102]. Esterification of estradiol aims to improves absorption and bioavailability after oral administration (such as with Estradiol valerate) or to sustain release from depot intramuscular injections (such as with Estradiol Cypionate) through improved lipophilicity. Following absorption, the esters are cleaved, resulting in the release of endogenous estradiol, or 17β-estradiol. Ester pro-drugs of estradiol are therefore considered to be bioidentical forms of estrogen [T84].
Estradiol valerate is commercially available as an intramuscular injection as the product Delestrogen and is indicated for the treatment of moderate to severe vasomotor symptoms and vulvovaginal atrophy due to menopause, for the treatment of hypoestrogenism due to hypogonadism, castration or primary ovarian failure, and for the treatment of advanced androgen-dependent carcinoma of the prostate (for palliation only). Estradiol valerate is also available in combination with [DB09123] as the commercially available product Natazia used for the prevention of pregnancy and for the treatment of heavy menstrual bleeding.
The primary source of estrogen in normally cycling adult women is the ovarian follicle, which secretes 70 to 500 mcg of estradiol daily, depending on the phase of the menstrual cycle. However, after menopause, most endogenous estrogen is produced by conversion of androstenedione, secreted by the adrenal cortex, to estrone by peripheral tissues. Thus, estrone and the sulfate conjugated form, estrone sulfate, are the most abundant circulating estrogens in postmenopausal women [FDA Label]. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol at the receptor level. Because of the difference in potency between estradiol and estrone, menopause (and a change in primary hormone from estradiol to estrone) is associated with a number of symptoms associated with this reduction in potency and in estrogenic effects. These include hot flashes, vaginal dryness, mood changes, irregular menses, chills, and sleeping problems. Administration of synthetic and bioidentical forms of estrogen, such as estradiol valerate, has shown to improve these menopausal symptoms.|