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GENITO URINARY SYSTEM AND SEX HORMONES › SEX HORMONES AND MODULATORS OF THE GENITAL SYSTEM › OTHER SEX HORMONES AND MODULATORS OF THE GENITAL SYSTEM › Progesterone receptor modulators
mifepristone
G03XB01
Adult Dosing
- Medical termination of intrauterine pregnancy through 70 days gestation: 200 mg orally on Day 1, followed by misoprostol 800 mcg buccally 24 to 48 hours later.
- Cushing syndrome (hyperglycemia management): 300 mg to 1200 mg orally once daily.
Pediatric Dosing
- Safety and efficacy not established in pediatric patients for termination of pregnancy.
- Not indicated for pediatric Cushing syndrome.
Indications
- Medical termination of intrauterine pregnancy through 70 days gestation (in a regimen with misoprostol)
- Control of hyperglycemia secondary to hypercortisolemia in adult patients with endogenous Cushing syndrome who have type 2 diabetes mellitus or glucose intolerance and are not candidates for surgery or have had unsuccessful surgery
Mechanism of Action
- Competitive progesterone receptor antagonist, blocking endogenous and exogenous progesterone action, leading to decidual breakdown, cervical softening, and detachment of the conceptus.
- High-affinity glucocorticoid receptor antagonist at higher doses, inhibiting cortisol activity and reversing clinical manifestations of hypercortisolemia.
Contraindications
- Confirmed or suspected ectopic pregnancy or intrauterine device (IUD) in place
- Chronic adrenal failure
- Concurrent long-term corticosteroid therapy
- History of allergy to mifepristone, misoprostol, or other prostaglandins
- Hemorrhagic disorders or concurrent anticoagulant therapy
- Inherited porphyrias
Adverse Reactions
- Uterine bleeding and heavy vaginal bleeding
- Uterine cramping and abdominal pain
- Nausea, vomiting, and diarrhea
- Dizziness, fatigue, and headache
- Fever, chills, and rigors
- Endometrial infection and sepsis (when used for termination)
- Hypokalemia, peripheral edema, and hypertension (when used for Cushing syndrome)
Drug Interactions
- CYP3A4 inhibitors (e.g., ketoconazole, erythromycin, grapefruit juice) may increase mifepristone plasma concentrations.
- CYP3A4 inducers (e.g., rifampin, dexamethasone, St. John's wort) may decrease mifepristone plasma concentrations.
- Coadministration with systemic corticosteroids antagonizes the therapeutic effects of mifepristone in Cushing syndrome.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) may theoretically decrease the efficacy of prostaglandins when used in termination regimens.
Curated Content: Needs Vetting Before Put to Clinical Use