Ulipristal acetate can be used in a medication abortion regimen

Ulipristal acetate, a treatment for uterine fibroids and an emergency contraceptive, can be used in combination with misoprostol as part of a medication abortion regimen, according to a proof-of-concept study. The results suggest that ulipristal acetate is as effective as mifepristone, which is also used with misoprostol for medication abortions. The finding could expand access to medication abortions because ulipristal acetate is more widely available than mifepristone. In Mexico, for example, it is sold over the counter without a prescription.

Researchers led by Beverly Winikoff, a physician and president of the reproductive health research organization Gynuity Health Projects, studied the ulipristal acetate–misoprostol regimen in 133 participants. People in the study had pregnancies of up to 63 days. They swallowed 60 mg of ulipristal acetate—twice the dose used for emergency contraception—in the clinic and then took 800 µg of misoprostol at home 24 h later. The regimen terminated pregnancy in 129 of the participants with no serious adverse side effects (NEJM Evidence 2025, DOI: 10.1056/EVIDoa2400209).

Medication abortions accounted for 63% of abortions in the US in 2023—up from 53% in 2020, according to research from the Guttmacher Institute, a reproductive health research and policy organization. That jump is likely due to a combination of state restrictions on abortion along with increased use of telehealth and mail-order drug delivery.

Winikoff says the team decided to study ulipristal acetate’s ability to induce abortion because of its structural similarity to mifepristone. The molecules differ by only two substituents. Ulipristal acetate “is in commerce already, so why not see what it can do?” she says.

Both molecules work by binding to progesterone receptors. Blocking progesterone thins the uterine lining so that it can’t support pregnancy, although researchers have not studied how ulipristal acetate induces abortion. The 30 mg dose used as an emergency contraceptive doesn’t affect an established pregnancy.

Daniel Grossman, a physician and professor of obstetrics, gynecology, and reproductive sciences at the University of California, San Francisco, who was not involved in the study, says that while the new data on ulipristal acetate look promising, “it's not enough yet to change practice.”

There was no comparison group used in the study, he says, so “we don't know if this is more effective than using misoprostol on its own, which can also be an effective abortion-inducing regimen.” Grossman says what’s needed next is a larger study with a comparison group using either mifepristone and misoprostol or misoprostol alone.

Perrigo markets ulipristal acetate as the emergency contraceptive Ella in the US and as EllaOne elsewhere. The company tells C&EN in an email that it has no plans to study the drug for medication abortion.

Grossman, who wrote a commentary that accompanies the study, says he worries that the results will lead to restrictions on ulipristal acetate, which has been a useful emergency contraceptive for more than a decade (NEJM Evidence 2025, DOI: 10.1056/EVIDe2400460). The drug can prevent pregnancy up to 5 days after unprotected sex and is more reliable than levonorgestrel, another emergency contraceptive, for people who have a high body mass index.

“The antiabortion movement has been saying for a long time that all hormonal contraception can cause an abortion, which is not true,” Grossman tells C&EN. “I'm worried that the antiabortion movement could misapply these findings to try to argue that ulipristal acetate for emergency contraception also causes an abortion, even though that's not what the study looked at, and that's not what the study found.”