Mifepristone: Main Uses and Therapeutic Overview

Mifepristone is a prescribed medication with two principal approved applications. It is used in a combination regimen with misoprostol for the medical termination of an intrauterine pregnancy up to 70 days of gestation (10 weeks). This regimen is an established option for ending an early pregnancy.

Additionally, mifepristone is authorized for the management and treatment of high blood sugar (hyperglycemia) in adult patients with endogenous Cushing's syndrome who also have Type 2 diabetes mellitus or glucose intolerance. This use is generally indicated for patients who have failed surgery or who are not candidates for a surgical procedure.

The therapeutic action of mifepristone works by blocking the effects of key hormones in the body. In the context of pregnancy, it interrupts the action of progesterone. For Cushing's syndrome, it manages symptoms by blocking the effects of excess cortisol at the receptor level. This dual therapeutic application is utilized in both reproductive health and endocrine management.

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Quick Facts on What Mifepristone Treats

• Medical Termination of Pregnancy: Used in combination with misoprostol to end an intrauterine pregnancy up to 70 days gestation.
• Cushing's Syndrome: Used to control high blood sugar associated with high cortisol levels in adults with endogenous Cushing's syndrome who have Type 2 diabetes or glucose intolerance and limited surgical options.

Who can and cannot use Mifepristone

Official eligibility for Mifepristone is strictly defined by regulatory authorities based on the patient population and the specific indication (medical termination of pregnancy [MTP] or Cushing's syndrome).

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Contraindicated Populations

Use is contraindicated in patients with a known hypersensitivity to the medicine, chronic adrenal failure, or inherited porphyrias. For MTP use, non-eligibility includes confirmed or suspected ectopic pregnancy, the presence of an intrauterine device (IUD), hemorrhagic disorders, concurrent anticoagulant therapy, or pregnancy beyond 70 days gestation.

Age and Organ Function Restrictions

Population Group	Regulatory Status
Pediatric (Cushing's use)	Safety and efficacy have not been established (Use not established).
Geriatric Patients	No information is available (Use not established).
Severe Hepatic Impairment	Not recommended (Cushing's use).
Mild to Moderate Hepatic/Renal Impairment	Use is restricted and requires a regulatory dose limitation (Cushing's use).

Pregnancy and Lactation Status

Use of Mifepristone for Cushing's syndrome is contraindicated in pregnancy. For MTP use, it is only indicated up to 70 days gestation. Lactation should be avoided during long-term therapy.

Mifepristone is associated with clinically significant interactions, primarily due to its effects as both a substrate and inhibitor of the Cytochrome P450 3A4 ( CYP3A4) enzyme pathway. Official regulatory information structures the interaction profile around three main concerns:

CYP3A4 Enzyme-Mediated Interactions

Interacting Product Category	Regulatory Requirement / Effect on Mifepristone
CYP3A4 Inducers (e.g., Rifampin, Phenytoin)	Must Not Be Used: Lowers mifepristone plasma concentrations, potentially reducing its effectiveness.
Strong CYP3A4 Inhibitors (e.g., Ketoconazole, Ritonavir)	Use with Caution/Monitoring: Increases mifepristone plasma concentrations, raising the risk of adverse effects. Grapefruit juice should also be avoided.
CYP3A4 Substrates (Narrow Therapeutic Margin)	Use with Extreme Caution/Contraindicated: Mifepristone inhibits CYP3A4, increasing the plasma concentration of co-administered medicines (e.g., Simvastatin, Cyclosporine). Specific drugs in this category are contraindicated for chronic mifepristone use.

Other Documented Interactions

• QT-Prolonging Drugs: Co-administration with medicines known to prolong the QT interval should be avoided due to the additive risk of serious cardiac rhythm abnormalities. Mifepristone itself can prolong the QTc interval in a dose-related manner.
• Hormonal Contraceptives: Concomitant use with hormonal contraceptives is not permitted.

Due to mifepristone's slow elimination, drug interactions involving enzyme inhibition may persist for approximately two to three weeks following discontinuation of chronic treatment. Regulatory documents emphasize close monitoring for patients receiving co-administered drugs that are substrates of CYP3A4, CYP2C8, or CYP2C9.

Мифепристон functions as a synthetic competitive antagonist at the intracellular Progesterone Receptor (PR) and, to a lesser extent, the Glucocorticoid Receptor (GR). The molecule exhibits a high affinity for the PR, exceeding that of its natural ligand, progesterone.

Upon entering target cells, primarily within the uterus, Мифепристон binds to the PR in the cytoplasm, preventing the binding of progesterone. This complex is unable to undergo the necessary conformational change, dimerization, and nuclear translocation required for binding to Progesterone Response Elements (PREs) on the DNA. Consequently, the drug inhibits the transcription of progesterone-dependent genes.

At the cellular level, this transcriptional repression leads to the destabilization of the uterine lining (endometrium) and an increase in prostaglandin synthesis and sensitivity. The altered signaling cascade ultimately results in increased contractility of the myometrium, or uterine smooth muscle. This system-level physiological consequence involves the modulation of tissue tone and structure via antagonism of endogenous steroidal hormone signaling.

The administration of Mifepristone utilizes specific clinical protocols based on the clinical context, utilizing the oral route for the tablet form.

Medical Termination of Pregnancy Regimen

The use of Mifepristone in a combination regimen for medical termination of pregnancy involves a single oral dose of 200 mg. This is followed by a buccal dose of 800 micrograms of Misoprostol administered 24 to 48 hours later. A post-treatment assessment is performed 7 to 14 days after the Mifepristone dose. Furthermore, any intrauterine device (IUD) is removed prior to initiating this treatment.

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Cushing’s Syndrome Management

For the management of Cushing’s syndrome, Mifepristone is used in a long-term maintenance course, beginning with an initial dose of 300 mg once daily. The tablet is taken with a meal and swallowed whole, without splitting, crushing, or chewing the tablet. The dose is adjusted based on response, but increases are limited to no more than once every two to four weeks, up to a maximum daily dose of 1200 mg.

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Population-Specific Instructions

Specific dose limitations apply to certain patient groups. For individuals with renal or mild-to-moderate hepatic impairment, the maximum daily dose is limited to 600 mg. Treatment for severe hepatic impairment is not recommended. These protocols, including the specific timing and dose adjustments, characterize the clinical application of the medicine.

Recent Clinical Evidence and Safety Profile

Mifepristone has been extensively studied for decades, primarily in the context of medical termination of pregnancy when used in a regimen with misoprostol. Clinical evidence, spanning nearly 40 years, consistently supports the safety and efficacy of this regimen for its indicated use up to 70 days (10 weeks) gestation.

Efficacy and Administration

Recent meta-analyses and large cohort studies affirm high effectiveness rates, generally ranging from 93% to 99%, when mifepristone (200 mg) is followed by misoprostol. Continuous research has informed changes in administration guidelines:

• Dosage: The standard dose has been optimized from 600 mg to 200 mg based on evidence showing comparable outcomes with the lower amount.
• Telehealth: Studies have demonstrated that medication abortion provided via telehealth, including mailing the medication after a consultation, maintains effectiveness and safety profiles comparable to in-person care.
• Location: Systematic reviews have found that the effectiveness and safety are consistent regardless of whether the mifepristone is administered at home or in a clinical setting.

Safety and Adverse Events

Regulatory bodies have reviewed the post-marketing safety data repeatedly. The risk of serious complications from the combined regimen is very low, reported as less than 1% in large U.S. cohorts.

Adverse Event (AE) Category	General Clinical Finding
Serious AEs	Rare (less than 1% of cases)
Common AEs	Abdominal pain, cramping, nausea, vomiting, and vaginal bleeding
Mortality Risk	Extremely rare; no deaths have been directly attributed to the drug alone since its approval.

The evidence supports that the medication is generally well-tolerated when used according to guidelines.

Common questions about Мифепристон (FAQ)

Q: How long does Mifepristone stay in your system after the final dose?

According to official regulatory information, the elimination of Mifepristone from the body is a two-phase process. After a single oral dose, the drug has a terminal elimination half-life estimated to be about 18 hours. For long-term use, regulatory information indicates that drug interaction effects due to liver enzyme modulation may persist for approximately two to three weeks after treatment is stopped.

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Q: What should I do if I miss a dose of Mifepristone for Cushing's syndrome?

Official patient information recommends taking the missed dose as soon as it is remembered. However, if it is nearly time for the next scheduled dose, the recommendation is to skip the missed dose and return to the regular schedule. It is advised that a double dose must not be taken to compensate for a missed dose.

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Q: What is the difference between Mifepristone 200 mg and 600 mg dosing?

The current standard dose for medical termination of pregnancy is 200 mg of Mifepristone. Regulatory documentation confirms that clinical evidence demonstrated the 200 mg dose had comparable effectiveness to the previous 600 mg dose for this indication.

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Q: Does Mifepristone have a serious risk of blood clots?

Regulatory warnings indicate that Mifepristone is contraindicated (should not be used) in patients with a hemorrhagic disorder or those who are taking anticoagulant therapy (blood thinners). This restriction is in place due to the risk of severe bleeding. The safety information cautions against use with blood thinners due to this risk.

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Q: What are the FDA-approved brand names for Mifepristone?

Official government databases and product labeling list two FDA-approved brand names for Mifepristone. MIFEPREX is the brand indicated for medical termination of pregnancy, and KORLYM is the brand indicated for the management of Cushing's syndrome. Generic versions are also available.

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Q: Is it safe to drive after taking Mifepristone?

Official safety information notes that common adverse effects of Mifepristone include dizziness, weakness, and general fatigue. Due to these potential effects, the official safety information advises that patients who experience these symptoms should use caution when performing tasks that require full attention, such as driving or operating machinery.

How to Store and Dispose of Mifepristone

Official Storage Conditions

Mifepristone tablets must be maintained at controlled room temperature, typically 20 C to 25 C (68 F to 77 F). The medication must be kept in the original container, tightly closed, to protect it from environmental degradation. It is required to protect the tablets from excess heat, moisture, and direct light.

Handling and Safety

Official labeling mandates that the product must not be allowed to freeze. For safety, the medication must be stored in a secure location, out of the reach and sight of children.

Disposal Requirements

Unused or expired Mifepristone should be disposed of in accordance with official guidelines. The preferred method is using an official drug take-back program. If a take-back option is unavailable, the recommended procedure is to mix the medicine with an unappealing substance (e.g., dirt) and place the mixture in a sealed container for household trash disposal.