Estradiol is a naturally occurring hormone circulating endogenously in females. It is commercially available in several hormone therapy products for managing conditions associated with reduced estrogen, such as vulvovaginal atrophy and hot flashes. Some available forms of estradiol include oral tablets, injections, vaginal rings, transdermal patches, sprays, gels, and creams.[L11485,L11488,L11491, L11494,L11497,L11500,L11503] When used for oral or IM administration, estradiol is commonly synthesized as a pro-drug ester (such as [DB13952], [DB13953], [DB13954], [DB13955], and [DB13956]). Because it has a low oral bioavailability on its own, estradiol is commonly formulated with an ester side-chain. [DB00977] (EE) is a synthetic form of estradiol commonly used as the estrogenic component of most combination oral contraceptive pills (OCPs). Ethinyl estradiol is different from estradiol due to its higher biovailability and increased resistance to metabolism, rendering it more suitable for oral administration.
Estradiol is indicated in various preparations for the treatment of moderate to severe vasomotor symptoms and vulvar and vaginal atrophy due to menopause, for the treatment of hypoestrogenism due to hypogonadism, castration, or primary ovarian failure, and for the prevention of postmenopausal osteoporosis. It is also used for the treatment of breast cancer (only for palliation therapy) in certain men or women with metastatic disease, and for the treatment of androgen-dependent prostate cancer (only for palliation therapy).[L11485,L11494,L11497] It is also used in combination with other hormones as a component of oral contraceptive pills for preventing pregnancy (most commonly as [DB00977], a synthetic form of estradiol). **A note on duration of treatment** Recommendations for treatment of menopausal symptoms changed drastically following the release of results and early termination of the Women's Health Initiative (WHI) studies in 2002 as concerns were raised regarding estrogen use.[A31626] Specifically, the combined estrogen–progestin group was discontinued after about 5 years of follow up due to a statistically significant increase in invasive breast cancer and in cardiovascular events.[A31627] Following extensive critique of the WHI results, Hormone Replacement Therapy (HRT) is now recommended to be used only for a short period (for 3-5 years postmenopause) in low doses, and in women without a history of breast cancer or increased risk of cardiovascular or thromboembolic disease.[A31628] Estrogen for postmenopausal symptoms should always be given with a progestin component due to estrogen's stimulatory effects on the endometrium; in women with an intact uterus, unopposed estrogen has been shown to promote the growth of the endometrium which can lead to endometrial hyperplasia and possibly cancer over the long-term.
Categories
Adrenal Cortex Hormones
Androgens and Estrogens
Anti-Gonadotropin-Releasing Hormones
Antiandrogens and Estrogens
BCRP/ABCG2 Inhibitors
COMT Substrates
Contraceptive Agents, Female
Contraceptives, Oral
Cytochrome P-450 CYP1A2 Inhibitors
Cytochrome P-450 CYP1A2 Inhibitors (weak)
Cytochrome P-450 CYP1A2 Substrates
Cytochrome P-450 CYP2C19 Substrates
Cytochrome P-450 CYP2C8 Substrates
Cytochrome P-450 CYP2C9 Substrates
Cytochrome P-450 CYP3A Substrates
Cytochrome P-450 CYP3A4 Substrates
Cytochrome P-450 CYP3A5 Substrates
Cytochrome P-450 CYP3A7 Substrates
Cytochrome P-450 Enzyme Inhibitors
Cytochrome P-450 Substrates
Drugs that are Mainly Renally Excreted
Estradiol Congeners
Estradiol, agonists
Estranes
Estrenes
Estrogen Contraceptives
Estrogens
Estrogens, agonists
Fused-Ring Compounds
Genito Urinary System and Sex Hormones
Gonadal Hormones
Gonadal Steroid Hormones
Hormonal Contraceptives for Systemic Use
Hormones
Hormones, Hormone Substitutes, and Hormone Antagonists
Hyperglycemia-Associated Agents
Hypothalamic Hormones
Intravaginal Contraceptives
Natural and Semisynthetic Estrogens, Plain
OAT3/SLC22A8 Substrates
OATP1B1/SLCO1B1 Inhibitors
OCT2 Inhibitors
P-glycoprotein substrates
Pituitary and Hypothalamic Hormones and Analogues
Progestogens and Estrogens, Sequential Preparations
Sex Hormones and Modulators of the Genital System
Steroids
Systemic Hormonal Preparations, Excl. Sex Hormones and Insulins
Drug Info/Drug Targets: DrugBank 3.0: a comprehensive resource for 'omics' research on drugs. Knox C, Law V, Jewison
T, Liu P, Ly S, Frolkis A, Pon A, Banco K, Mak C, Neveu V, Djoumbou Y, Eisner R, Guo AC, Wishart DS.
Nucleic Acids Res. 2011 Jan; 39 (Database issue):D1035-41. | PMID:21059682
