17α-Estradiol

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17α-Estradiol (also known as 17α-E2 or 17-epiestradiol) is a naturally occurring estrogen and a minor female sex hormone. It is an epimer of estradiol (17β-estradiol), the predominant and most potent estrogen.

Biological Role

17α-Estradiol is produced in the ovaries, adrenal glands, and placenta. It has a similar but weaker effect compared to 17β-estradiol. It binds to estrogen receptors and can influence various physiological processes, including the menstrual cycle, reproductive system, and bone density.

Medical Uses

17α-Estradiol is used in the treatment of androgenic alopecia (pattern hair loss) in both men and women. It is available in topical formulations and is believed to work by modulating the effects of androgens on hair follicles.

Mechanism of Action

17α-Estradiol exerts its effects by binding to estrogen receptors (ERα and ERβ) in target tissues. This binding leads to the activation or repression of specific genes, resulting in the modulation of various biological functions.

Pharmacokinetics

The pharmacokinetics of 17α-estradiol involve its absorption, distribution, metabolism, and excretion. It is metabolized primarily in the liver and excreted in the urine.

Safety and Side Effects

The safety profile of 17α-estradiol is generally favorable when used as directed. Common side effects may include local irritation at the site of application. Systemic side effects are rare due to its limited absorption when used topically.

Research

Research on 17α-estradiol is ongoing to explore its potential benefits in other medical conditions, including its role in neuroprotection and anti-aging.

See Also

• Estradiol
• Estrogen
• Androgenic alopecia
• Estrogen receptor

References

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