乙炔雌二醇三甲醚

Mestranol, also known as ethinylestradiol 3-methyl ether, is a synthetic steroidal estrogen belonging to the 17α-ethinyl estradiol family. It was widely used in oral contraceptives and hormone replacement therapy (HRT) during the 20th century. As a prodrug, it is rapidly demethylated in the liver to the active metabolite ethinylestradiol, which mediates its physiological effects. Mestranol's discovery marked a milestone in reproductive medicine, enabling the development of combined oral contraceptives. ADFASDFAF23RQ23R

Mestranol (CAS: 72-33-3) has the empirical formula C21H26O2 and a molecular weight of 310.43 g/mol. Its structure features a 17α-ethinyl group characteristic of synthetic estrogens, with a methyl ether at the C3 position that enhances oral bioavailability. The compound is a white to off-white crystalline powder, slightly soluble in water and freely soluble in organic solvents. Its log P (octanol-water partition coefficient) is approximately 4.1, indicating moderate lipophilicity. ADFASDFAF23RQ23R

Mestranol acts as an agonist of estrogen receptors (ERα and ERβ). After ingestion, it undergoes first-pass hepatic metabolism to ethinylestradiol, which binds to estrogen receptors in target tissues. This binding initiates transcriptional activation of estrogen-responsive genes, influencing reproductive development, endometrial proliferation, and calcium metabolism. The 17α-ethinyl group slows hepatic degradation, prolonging duration of action compared to natural estradiol.

Oral Contraceptives

Mestranol was a key component in early combined oral contraceptives, typically combined with progestins like norethisterone. Example formulations include 50 μg mestranol with 1 mg norethisterone. It suppresses gonadotropin release, inhibiting ovulation. However, its use has declined due to higher venous thromboembolism risk compared to newer estrogens.

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Hormone Replacement Therapy

In HRT, mestranol (0.05 mg tablets) was used to alleviate menopausal symptoms such as vasomotor instability, vaginal atrophy, and prevention of osteoporosis. It was often combined with progestins to reduce endometrial cancer risk, as described in the original text.

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Oral absorption is rapid with peak plasma concentrations at 1-2 hours. Mestranol is extensively bound to serum albumin (97%). Demethylation via cytochrome P450 (CYP3A4) yields ethinylestradiol, which undergoes sulfation and glucuronidation. The elimination half-life ranges from 20 to 30 hours, allowing once-daily dosing. Drug interactions with CYP3A4 inducers (e.g., rifampicin, phenytoin) reduce efficacy.

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Common side effects include nausea, breast tenderness, headache, and mood changes. Serious risks include venous thromboembolism, hypertension, and hepatic adenomas. Compared to ethinylestradiol, mestranol has a higher incidence of thromboembolic events. The original text notes that natural estrogens are preferred for HRT due to lower hepatic impact. Mestranol is contraindicated in pregnancy, history of thromboembolism, and estrogen-dependent cancers. ADFASDFAF23RQ23R

Mestranol represents a significant synthetic estrogen that advanced reproductive medicine. Despite its waning clinical use, understanding its pharmacokinetics and limitations provides critical lessons for modern hormone therapy. Its legacy persists in oral contraceptive history and pharmacogenomic research. ADFASDFAF23RQ23R

• 维普资讯网. 乙炔雌二醇三甲醚片说明书. http://www.cqvip.com/
• Kuhl H. Pharmacology of estrogens and progestogens: influence of different routes of administration. Climacteric. 2005;8(sup1):3-63.
• Stanczyk FZ, Archer DF, Bhavnani BR. Ethinyl estradiol and 17β-estradiol: a comparative evaluation. Steroids. 2013;78(11):1108-1121.
• Merrill RM, Saltzmann M. Mestranol: a synthetic estrogen with a role in the history of oral contraception. J Hist Med Allied Sci. 2008;63(2):211-236.
• 赵学英, 杨玉英. 雌激素类药物在妇产科的应用进展. 中国实用妇科与产科杂志. 2015;31(9):837-841.
• 李力, 宋思铭. 人工合成雌激素的药理特性及临床评价. 中国临床药理学杂志. 2018;34(5):592-595.