Mifepristone

• Mifepristone is a synthetic steroid that blocks progesterone, a hormone vital for pregnancy.
• It is primarily used in combination with misoprostol for medical termination of early pregnancy.
• Mifepristone can also be used to manage high blood sugar in adults with endogenous Cushing’s syndrome.
• Common side effects include abdominal cramping, vaginal bleeding, nausea, and fatigue.
• It is administered under strict medical supervision due to its specific indications and potential risks.

What is Mifepristone and How It Works

Mifepristone is an antiprogestational steroid that works by blocking the effects of progesterone. Progesterone is a naturally occurring hormone that plays a critical role in preparing the uterus for pregnancy and maintaining it once conception has occurred. By binding to progesterone receptors without activating them, mifepristone effectively prevents progesterone from exerting its effects. This action leads to several physiological changes, including the shedding of the uterine lining and softening of the cervix.

The mechanism of action of mifepristone is pivotal in its clinical applications. In the context of pregnancy termination, this blockade of progesterone causes the uterine lining to break down, detaching the embryo. It also increases the sensitivity of the uterus to prostaglandins, which are compounds that induce uterine contractions. This makes mifepristone highly effective when used in conjunction with a prostaglandin analog like misoprostol, which further aids in expelling the uterine contents. The combined effect ensures a comprehensive approach to its intended medical use.

What is Mifepristone Used For?

Mifepristone has specific and regulated uses in medical practice. Its primary application is in the medical termination of early intrauterine pregnancy. This procedure typically involves a two-drug regimen: mifepristone followed by misoprostol. The U.S. Food and Drug Administration (FDA) has approved mifepristone for this purpose up to 70 days (10 weeks) of gestation, measured from the first day of the last menstrual period. According to the Guttmacher Institute, medical abortion accounts for a significant percentage of all abortions in the United States, with mifepristone being a key component in these procedures.

Beyond its use in reproductive health, mifepristone also has an important application in endocrinology. It is approved for the control of high blood sugar (hyperglycemia) in adults with endogenous Cushing’s syndrome who have type 2 diabetes mellitus or glucose intolerance and are not candidates for surgery or have failed surgery. In this context, mifepristone acts as a glucocorticoid receptor antagonist, blocking the effects of excess cortisol, which is characteristic of Cushing’s syndrome. This dual utility highlights the medication’s diverse pharmacological profile.

Mifepristone Side Effects, Safety, and Drug Information

As with any medication, Mifepristone side effects and safety considerations are important. Common side effects often include:

• Abdominal cramping
• Vaginal bleeding, which can be heavier than a typical menstrual period
• Nausea and vomiting
• Diarrhea
• Dizziness and fatigue

More serious, though less common, side effects can include severe infection, prolonged heavy bleeding requiring medical intervention, or an incomplete abortion requiring surgical follow-up. Patients are typically advised to seek immediate medical attention if they experience fever, severe abdominal pain, or heavy bleeding that soaks through two pads in an hour for two consecutive hours.

Comprehensive Mifepristone drug information emphasizes the importance of administration under the supervision of a qualified healthcare provider. Contraindications include confirmed or suspected ectopic pregnancy, chronic adrenal failure, and known hypersensitivity to mifepristone or any component of the product. It is also not recommended for use in patients with inherited porphyrias or those on long-term corticosteroid therapy. Patients should be thoroughly counseled on the procedure, potential risks, and follow-up care. The FDA mandates a Risk Evaluation and Mitigation Strategy (REMS) for mifepristone to ensure that its benefits outweigh its risks, requiring specific conditions for its distribution and use.