The recent Supreme Court decision overturning Roe v. Wade has heightened interest in the use of the oral antiprogestin mifepristone (Mifeprex) for termination of intrauterine pregnancies. Mifepristone binds to progesterone receptors and increases prostaglandin levels by inhibiting prostaglandin dehydrogenase; both actions stimulate uterine contractility. It is generally used with the prostaglandin analog misoprostol (Cytotec, and generics), which has an additive effect on uterine contractility.

The Medical Letter first reviewed mifepristone shortly after it was first approved by the FDA in 2000 for use with oral misoprostol in women with pregnancies of up to 49 days. A large study in women with pregnancies of up to 56 days found that oral mifepristone followed 24 to 72 hours later by intravaginal insertion of misoprostol led to complete abortions in 96-98% of patients. In other studies, oral misoprostol alone led to abortions in 70-80% of women. Vaginal bleeding and abdominal cramps were the main side effects. Bleeding persisted for a median of 9-16 days, somewhat longer than after suction curettage. The original label called for 3 office visits: one to take mifepristone, another 2 days later to take misoprostol, and the last after 14 days to confirm that the pregnancy had been terminated.1

Fifteen years passed before our next article, which described changes in the labeling of the drug. The new label called for use in pregnancies of up to 70 days, a lower dose of mifepristone, a higher dose of misoprostol to be administered buccally, and administration of misoprostol could now take place at home. Mifepristone continued to be available, however, only through a REMS program to certified prescribers and could only be dispensed in a clinic, medical office, or hospital where ultrasound was available.2

Our most recent article on mifepristone, published in January of this year, reported the FDA’s removal of the requirement that mifepristone must be dispensed in person to the patient, which will allow certified prescribers or certified pharmacies to dispense the drug to patients by mail. Our article concluded: A single 200-mg oral dose of mifepristone followed 24-48 hours later by a single 800-mcg buccal dose of misoprostol terminates early intrauterine pregnancies in about 95% of women.3-5

The continued availability of mifepristone in all states of the US is uncertain.

  1. Mifepristone (RU 486). Med Lett Drugs Ther 2000; 42:101.
  2. Mifepristone (Mifeprex) label changes. Med Lett Drugs Ther 2016; 58:55.
  3. In Brief: Mifepristone by Mail for Pregnancy Termination. Med Lett Drugs Ther 2022; 64:11.
  4. UD Upadhyay et al. Safety and efficacy of telehealth medication abortions in the US during the COVID-19 pandemic. JAMA Netw Open 2021; 4:e2122320.
  5. L Schummers et al. Abortion safety and use with normally prescribed mifepristone in Canada. N Engl J Med 2022; 386:57.

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