What Is Misoprostol, the Other Drug Commonly Prescribed for Abortions?

An order by a federal judge in Texas invalidating the approval of the abortion pill mifepristone did not apply to the second drug used in the typical two-medication abortion regimen, misoprostol.

For now, mifepristone remains legally approved, and it’s possible the drug will remain available while the court case winds through the appeals process.

But if the Texas ruling is ultimately upheld, many clinics and services are prepared to prescribe misoprostol on its own to patients seeking abortions in early pregnancy, an option that the World Health Organization endorses as safe and effective.

What is misoprostol?

Misoprostol has several medical uses, including as a treatment for stomach ulcers. It is used by obstetricians to help some patients give birth because it can help induce labor and ripen the cervix.

Misoprostol is readily available by prescription at retail pharmacies and has never been subject to the regulatory restrictions that the Food and Drug Administration applied to mifepristone.

How is it used in abortions?

In the United States, medication abortion is used for patients who are less than 12 weeks into pregnancy. The typical protocol for medication abortion has been to take one pill of mifepristone, which blocks a hormone necessary for a pregnancy to develop, followed 24 to 48 hours later by misoprostol, which causes contractions and helps the body expel the pregnancy tissue. The same regimen is also used to treat patients who are experiencing miscarriages.

The typical dose is four misoprostol tablets placed in the cheeks or under the tongue to dissolve or inserted vaginally. For patients whose pregnancies are between 10 weeks’ and 12 weeks’ gestation, doctors usually prescribe a second dose of four tablets to be taken several hours after the first dose.

Is it safe to use without taking mifepristone first?

Misoprostol alone is used in abortions in a number of other countries, especially those where mifepristone is unavailable.

A recent analysis, published in the journal Contraception, reported that misoprostol on its own is “very safe”; at most 0.7 percent of patients experienced complications that needed hospitalization or a blood transfusion. It can be more likely than the two-drug regimen to cause side effects like nausea, chills and diarrhea, the analysis said.

Studies suggest that taking only misoprostol may be somewhat less effective than taking it in combination with mifepristone, meaning that some patients may need additional medication or, in a subset of cases, a surgical evacuation procedure to complete the abortion.

The new analysis said studies had found that misoprostol-only protocols resulted in a complete abortion 78 percent to 98 percent of the time. The variation in effectiveness appeared to be related to factors like how many doses of misoprostol patients received and how the drug was taken. There was also some variation in the circumstances of patients in different countries where the studies were reported.

The analysis said that, based on the studies, giving patients three or more four-tablet doses of misoprostol every three hours, either under the tongue or vaginally, gave the protocol the greatest chance of resulting in a complete abortion. It said there was less research on using misoprostol on its own between 10 and 12 weeks of pregnancy.

The effectiveness of the two-drug combination of mifepristone and misoprostol is consistently about 95 percent, the study said.

Is misoprostol in danger of being banned too?

In the Texas lawsuit, the plaintiffs, a coalition of groups and doctors opposed to abortion, also seek to ban the use of misoprostol for abortion, but their request for a preliminary injunction focused on mifepristone and the judge ruled only on that. Wyoming recently passed a law that bans all forms of medication abortion in that state. That law is scheduled to take effect on July 1 unless a legal challenge succeeds in blocking it.