Pharmacodynamics properties
- Being an antiprogestin
- Contraception is an action happening before a nesting of fertilized ovum. Double effects include prevention of ovulation and prevention of endothelial growth. The most important effect is to slow ovulation by disrupting the follicular growth and the endocrine function of granular cells and preventing LH at the middle of the cycle. It also works on the endothelium if used after ovulation and affecting the nesting. In addition, 50% of women with macular degeneration make their endothelium peel off easily.
- Mifepristone acts as a progesterone-receptor antagonist by competing with endogenous progesterone on receptor binding. Mifepristone’s binding affinity is very high for these receptors (2-10 times that of progesterone).
- Mifepristone prevents the effects of progesterone on the endometrium and peritoneum. This leads to degeneration and exudation of the endometrial mucosa, thus preventing or disrupting fetal attachment.
Pharmacokinetic properties
- The bioavailability of mifepristone is approximately 70% after oral administration. Time to peak plasma concentrations of mifepristone occurred between 1 and 2 hours following single dose. The half-life is about 20 to 30 hours. The unbound mifepristone is rapidly metabolized by demethylation and hydroxylation in the liver. The metabolism can be detected in plasma about 1 hour after ingestion.
- Mifepristone and its metabolites are mainly excreted in feces through the biliary tract and some excreted by the kidneys.
Indications
Mifepristone is used for emergency contraception cases after unprotected intercourse.
Dosage & administration
- For oral use only.
- One tablet should be given within 120 hours after sex. However, use as soon as effective.
- Do not use more than 2 times in one menstrual cycle.
Contraindications
- Adrenal disease or uncontrolled severe asthma.
- Receiving treatment with corticosteroids.
- Allergy to mifepristone.
- Pregnant or breastfeeding women.
Precautions
- Mifepristone cannot replace regular contraceptive methods.
- Unprotected intercourse after treatment may increase the risk of unintended pregnancy.
-Mifepristone is used with caution in patients with asthma, chronic respiratory obstruction, hemorrhage or cardiovascular disease or factors related to anemia.
- Mifepristone is also warned to be unsafe for patients with porphyria.
Interactions
- Ketoconazole, itraconazole, erythromycin and fruit juices (grapes) can prevent the misfepriston catabolism (increased serum concentrations).
- Increased metabolism of mifepristone (decreased serum concentrations) may be reported by co-administration with rifampion, dexamethasone and anticonvulsants (including phenytoin, phenobarbital, carbamazepine).
- Nonsteroidal anti-inflammatory drugs (NSAIDs) are an anti-prostaglandin drug that reduces the therapeutic effect of mifepristone.
Pregnancy and lactation
- A dose of 10 mg of mifepristone do not cause abortions but can occur bleeding in pregnant women.
- Mifepristone crosses into breast milk. However, the effects of a dose of 10-mg mifepristone on infant have not been established.
Effect on the ability to drive and use machines
No data showing an effect on the ability to drive or using machines are known.
Undesirable effects
In addition to delayed menstruation, other adverse effects are rare and mild.
Common side effects are bleeding, nausea, vomiting, diarrhea, lower abdominal pain, fatigue, chills, headache, dizziness, chest tightness, skin rash, and urticaria.
Inform your doctor about any side effects that may occur during the treatment.
Overdose
Clinical trials have shown that no side effects occur with a single dose of up to 2 g of mifepristone. If acute poisoning occurs, patients should be hospitalized for monitoring and special treatment.
Shelf-life: 36 months from the manufacturing date.
Storage: Store in cool dry places, below 30oC, avoid direct light.
Specifications: Manufacturer’s.
Registration number: QLĐB-488-15