A Closer Look at the Abortion Medication Mifepristone

Research Corner
April 18, 2023

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Soleil Shah, MSc, Research Reporter

Soleil Shah writes Tradeoffs’ Research Corner, a weekly newsletter bringing you original analysis, interviews with leading researchers and more to help you stay on top of the latest health policy research.

A closer look at the abortion medication mifepristone

A pair of recent, conflicting court rulings has thrust a small white pill into the center of the country’s ongoing reckoning with abortion rights.

The pill, known generically as mifepristone and sold under the brand name Mifeprex, is used to facilitate hundreds of thousands of medication abortions each year. Now its availability is in jeopardy.

While we don’t yet know how the Supreme Court will rule next on this issue, I wanted to focus today’s Research Corner on what we do know about the drug at the center of this legal maelstrom.

What is mifepristone?

Mifepristone, also known as the abortion pill or RU-486, was approved by the FDA in 2000 for ending pregnancies within the first 10 weeks. It works by blocking the hormone progesterone, which is needed for a pregnancy to continue. This causes the lining of the uterus to break down and the fetal tissue to be released from the body.

One to two days after taking a single mifepristone tablet, patients usually receive another medication known as misoprostol, which helps to empty the uterus. Over half of abortions performed in the U.S. use this combination of medications.

Mifepristone is also frequently used off-label, meaning without explicit approval from the FDA, to help the 10 to 20% of pregnant people who suffer miscarriages each year.

How effective is mifepristone? 

Studies have shown that mifepristone, when used in combination with misoprostol, is successful at ending 95 to 98% of first-trimester pregnancies. This medication combination has also been shown to be a more reliable way to treat miscarriages, with fewer complications, than using misoprostol alone. 

Known side effects of mifepristone include vaginal bleeding, stomach pain, nausea, and vomiting. These are expected since the drug works by essentially causing a miscarriage, and eventually go away on their own.

Despite these side effects, the evidence on mifepristone’s use overwhelmingly suggests that it is safe for medication abortions, with a complication rate less than 1%. Compare this to the complication rate for appendix removal, a common surgery, which can be as high as 31%

What options do patients have if mifepristone comes off the market? 

If mifepristone becomes harder to access, a few options remain. Patients seeking abortion could:

  1. Use the drug misoprostol on its own.
    Although evidence suggests misoprostol alone can be nearly as effective as mifepristone and misoprostol together, there may be higher rates of complications with misoprostol alone. Complications can lead patients to the emergency department, which could increase their legal risk in states with strict abortion restrictions.
  2. Undergo a procedure known as aspiration or suction. 
    Aspiration abortions tend to be somewhat more effective than medication abortions, but take longer to perform, can cost more and carry a slightly higher complication risk. 
  3. Buy mifepristone internationally or try to get a doctor to prescribe a version of mifepristone approved for a rare disease.
    Patients who take either of these routes may be able to access mifepristone, but not receive insurance coverage, making it less affordable. Depending on the state they live in, they could also be at legal risk

A court has never overturned an FDA drug approval, but the possibility now casts uncertainty over the lives of thousands of pregnant people, abortion providers – and even the entire pharmaceutical industry

One researcher I spoke with, Ushma Upadhyay, told me that it’s too early to say how all this will play out, but that the FDA could use a legal tool called “enforcement discretion” to keep mifepristone available. 

Family doctor Vanessa Ramirez, a fellow at Physicians for Reproductive Health, said her clinic in California is preparing to offer more aspiration procedures and misoprostol-only medication abortions. 

We will continue to follow this case and its implications in the weeks to come.