Does Mifeprex (mifepristone) cause side effects?
Progesterone is a female hormone and the principal progestational hormone. Progesterone prepares the uterus (the womb) to receive and sustain the fertilized egg and is an important hormone for sustaining pregnancy.
Mifeprex terminates early pregnancy by blocking the activity of progesterone at progesterone receptors. It also stimulates contraction of the uterus. Early pregnancy is considered to be 49 days (7 weeks) since the last menstrual period began. Mifeprex must be used in combination with misoprostol for the purpose of termination of pregnancy.
Cortisol is a metabolite of the hormone cortisone, and is an essential factor in many processes including the proper metabolism of starches, and it is the major natural glucocorticoid in humans. People with Cushing syndrome produce too much cortisol, and, among many other effects, develop high glucose (sugar) levels in the blood. Mifeprex reduces blood glucose levels in people with Cushing syndrome by blocking the activity of cortisol.
Common side effects of Mifeprex include
Serious side effects of Mifeprex include
- allergic reactions,
- low blood pressure,
- loss of consciousness,
- infections after abortion,
- ruptured ectopic pregnancy,
- shortness of breath,
- rapid heartbeat, and
- collection of blood in the uterus (hematometra).
Drug interactions of Mifeprex include ketoconazole, itraconazole, erythromycin, and grapefruit juice, which may increase blood levels of Mifeprex by inhibiting the enzyme responsible for metabolizing (breaking down) Mifeprex.
- Rifampin, dexamethasone, St. John's wort, phenytoin, phenobarbital, and carbamazepine may decrease blood levels of Mifeprex by increasing the activity of the enzyme responsible for metabolizing Mifeprex and decrease the effectiveness of Mifeprex.
- Mifeprex may inhibit liver enzymes which are responsible for the metabolism of various drugs, resulting in increased blood levels of these drugs.
Mifeprex is used for the termination of pregnancy through the 49th day of pregnancy. Otherwise, it should not be used during pregnancy because it will terminate the pregnancy.
What are the side effects of Mifeprex (mifepristone)?
Commonly reported side effects include
Less common but severe side effects include
Mifeprex (mifepristone) side effects list for healthcare professionals
The following adverse reactions are described in greater detail in other sections:
- Infection and sepsis
- Uterine bleeding
Clinical Trials Experience
Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.
Information presented on common adverse reactions relies solely on data from U.S. studies, because rates reported in non-U.S. studies were markedly lower and are not likely generalizable to the U.S. population.
In three U.S. clinical studies totaling 1,248 women through 70 days gestation who used mifepristone 200 mg orally followed 24-48 hours later by misoprostol 800 mcg buccally, women reported adverse reactions in diaries and in interviews at the follow-up visit.
These studies enrolled generally healthy women of reproductive age without contraindications to mifepristone or misoprostol use according to the Mifeprex product label.
About 85% of patients report at least one adverse reaction following administration of Mifeprex and misoprostol, and many can be expected to report more than one such reaction. The most commonly reported adverse reactions (>15%) were
The frequency of adverse reactions varies between studies and may be dependent on many factors, including the patient population and gestational age.
Abdominal pain/cramping is expected in all medical abortion patients and its incidence is not reported in clinical studies. Treatment with Mifeprex and misoprostol is designed to induce uterine bleeding and cramping to cause termination of an intrauterine pregnancy.
Uterine bleeding and cramping are expected consequences of the action of Mifeprex and misoprostol as used in the treatment procedure. Most women can expect bleeding more heavily than they do during a heavy menstrual period.
Table 1 lists the adverse reactions reported in U.S. clinical studies with incidence >15% of women.
Table 1: Adverse Reactions Reported in Women Following Administration of Mifepristone (oral) and Misoprostol (buccal) in U.S. Clinical Studies
|Adverse Reaction||# U.S. studies||Number of Evaluable Women||Range of frequency (%)||Upper Gestational Age of Studies Reporting Outcome|
One study provided gestational-age stratified adverse reaction rates for women who were 57-63 and 64-70 days; there was little difference in frequency of the reported common adverse reactions by gestational age.
Information on serious adverse reactions was reported in six U.S. and four non-U.S. clinical studies, totaling 30,966 women through 70 days gestation who used mifepristone 200 mg orally followed 24-48 hours later by misoprostol 800 mcg buccally. Serious adverse reaction rates were similar between U.S. and non-U.S. studies, so rates from both U.S. and non-U.S. studies are presented.
In the U.S. studies, one studied women through 56 days gestation, four through 63 days gestation, and one through 70 days gestation, while in the non-U.S. studies, two studied women through 63 days gestation, and two through 70 days gestation.
Serious adverse reactions were reported in <0.5% of women. Information from the U.S. and non-U.S. studies is presented in Table 2.
Table 2: Serious Adverse Reactions Reported in Women Following Administration of Mifepristone (oral) and Misoprostol (buccal) in U.S. and Non-U.S. Clinical Studies
|# of studies||Number of Evaluable Women||Range of frequency (%)||# of studies||Number of Evaluable Women||Range of frequency (%)|
|Hospitalization Related to Medical Abortion||3||14,339||0.04-0.6%||3||1,286||0-0.7%|
|Infection without sepsis||1||216||0||1||11,155||0.2%|
|NR= Not reported|
* This outcome represents a single patient who experienced death related to sepsis.
The following adverse reactions have been identified during postapproval use of Mifeprex and misoprostol. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Blood and the lymphatic system disorders: anemia
Psychiatric disorders: anxiety
Respiratory, thoracic and mediastinal disorders: shortness of breath
Gastrointestinal disorders: dyspepsia
Reproductive system and breast disorders: uterine rupture, ruptured ectopic pregnancy, hematometra, leukorrhea
General disorders and administration site conditions: pain
Which drugs interact with Mifeprex (mifepristone)?
Drugs That May Reduce Mifeprex Exposure (Effect Of CYP 3A4 Inducers On Mifeprex)
- CYP450 3A4 is primarily responsible for the metabolism of mifepristone. CYP3A4 inducers such as rifampin, dexamethasone, St. John's Wort, and certain anticonvulsants (such as phenytoin, phenobarbital, carbamazepine) may induce mifepristone metabolism (lowering serum concentrations of mifepristone).
- Whether this action has an impact on the efficacy of the dose regimen is unknown. Refer to the follow-up assessment to verify that treatment has been successful.
Drugs That May Increase Mifeprex Exposure (Effect Of CYP 3A4 Inhibitors On Mifeprex)
- Although specific drug or food interactions with mifepristone have not been studied, on the basis of this drug's metabolism by CYP 3A4, it is possible that ketoconazole, itraconazole, erythromycin, and grapefruit juice may inhibit its metabolism (increasing serum concentrations of mifepristone).
- Mifeprex should be used with caution in patients currently or recently treated with CYP 3A4 inhibitors.
Effects Of Mifeprex On Other Drugs (Effect Of Mifeprex On CYP 3A4 Substrates)
- Based on in vitro inhibition information, coadministration of mifepristone may lead to an increase in serum concentrations of drugs that are CYP 3A4 substrates.
- Due to the slow elimination of mifepristone from the body, such interaction may be observed for a prolonged period after its administration.
- Therefore, caution should be exercised when mifepristone is administered with drugs that are CYP 3A4 substrates and have narrow therapeutic range.
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Related Disease Conditions
Early Pregnancy Symptoms and Signs
Pregnancy symptoms can vary from woman to woman, and not all women experience the same symptoms. When women do experience pregnancy symptoms they may include symptoms include missed menstrual period, mood changes, headaches, lower back pain, fatigue, nausea, breast tenderness, and heartburn. Signs and symptoms in late pregnancy include leg swelling and shortness of breath. Options for relief of pregnancy symptoms include exercise, diet, and other lifestyle changes.
Bleeding During Pregnancy (First Trimester)
Bleeding during pregnancy is never normal. Causes of bleeding during the first trimester of a pregnancy may be caused by implantation bleeding, ectopic or tubal pregnancy, subchorionic hemorrhaging, infections, and miscarriage. Bleeding during the second and third trimesters of pregnancy can be caused by a variety of factors.
Ectopic Pregnancy (Tubal Pregnancy)
An ectopic pregnancy is a pregnancy located outside the inner lining of the uterus. The majority of ectopic pregnancies occur in the Fallopian tube. Signs and symptoms of an ectopic pregnancy may include abdominal pain, lack of menstrual period (amenorrhea), vaginal bleeding, fainting, dizziness, and low blood pressure. Treatment options for an ectopic pregnancy include observation, medication, or surgery.
Early Signs and Symptoms of Pregnancy
The signs and symptoms of pregnancy differ from woman to woman. All the signs of pregnancy may not be seen in one person. Additionally, the signs may appear in different persons at different times.
Treatment & Diagnosis
Medications & Supplements
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.