Misoprostol-Only for Abortion: Viable Option but Not 'the Best'

Robert Fulton

April 13, 2023

With a federal judge's recent ruling clouding the future availability of mifepristone for terminating pregnancies, attention has shifted to the efficacy of another abortion drug, misoprostol.

Experts said a misoprostol-only regimen for medical abortions is as safe as but not as effective as the combination of mifepristone and misoprostol. A misoprostol-only approach also comes with more pronounced side effects.

"Misoprostol only is a good alternative; it's not the best alternative," said Beverly Gray, MD, an associate professor in the Department of Obstetrics and Gynecology at Duke University, in Durham, North Carolina, during a video conference Wednesday. "The best medication would be to use mifepristone and misoprostol together because they're efficacious with fewer side effects."

To medically terminate a pregnancy using the two-drug regimen, patients first take the progesterone blocker mifepristone, which ends the pregnancy. That is followed 24 to 48 hours later with misoprostol, which causes the uterus to expel the pregnancy tissue. Used in combination, the two drugs have an efficacy rate of 98% in terminating a pregnancy.

An alternative approach is a misoprostol-only regimen. Patients take multiple doses of the drug over the course of hours until the pregnancy passes. This method is considered effective and safe, although patients may experience more nausea, vomiting, diarrhea, bleeding, and cramping.

Dr Mitchell Creinin

"It's effective, but not as effective as the combination treatment," said Mitchell Creinin, MD, a professor in the Department of Obstetrics and Gynecology at UC Davis Health. "It also requires much higher doses. To get misoprostol by itself to have relatively high efficacy, you have to use multiple doses. It causes significantly more side effects, and it's less effective."

Creinin was part of a team that earlier this year conducted a study of misoprostol-only medical abortions. In that study, which was published in the journal Contraception, the investigators found that the misoprostol-only regimen was 78% effective at aborting completely without a procedure or unplanned additional medications. The investigators concluded that prohibiting the use of mifepristone was "senseless" but that offering misoprostol-only abortions would be a "safe, effective and patient-centered approach."

Both drug regimens are intended to be used during the first trimester of pregnancy, and their effectiveness is influenced by the gestation period.

Medical abortions have grown in popularity. They now account for more than half of all abortions. Last year's US Supreme Court decision in Dobbs v. Jackson Women's Health Organization overturned the court's 1973 ruling in Roe v. Wade, leaving it up to states to regulate abortion. Currently, nearly half of states have banned or are considering some sort of ban on the procedure, according to the Guttmacher Institute, a reproductive health advocacy group.

"Medication abortion is good for privacy in many ways," said Jolynn Dellinger, JD, a visiting lecturer at Duke Law School, during the conference call with Gray. "It's incredibly safe and effective and can be the very best choice for people."

On April 7, a federal judge in Texas suspended the US Food and Drug Administration approval of mifepristone. The drug has been on the market for 23 years. A federal judge in Washington State issued a competing ruling, and the Biden Administration has appealed the Texas decision.

The future of the use of mifepristone is now in the courts, but not that of misoprostol ― for now. The latter is used to prevent ulcers; its use in medical abortions is secondary. Creinin said that that will make it much more difficult for antiabortion advocates to challenge.

While courts, lawmakers, and regulators at the state and federal levels work through what is allowable for medical abortions, the medical community sits and waits.

"We're working out a variety of scenarios," Gray said. "I think right now we're just hoping that the legislative dust will settle enough so that we'll have a better understanding. In the meantime, we're creating protocols and trying to be as prepared as we can."

Robert Fulton is a journalist living in Los Angeles.

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