What will happen if medication abortion challenge succeeds?

Medication abortions in the United States usually involve two different drugs.

In the latest effort to limit abortion access, opponents of the procedure are seeking to ban one of those medications. If they succeed, only one of the pills would be available, but women would still be able to get abortions.

Here’s a look at medications, efforts to curtail them and how clinics are responding.

The drugs

The Food and Drug Administration regimen for medication abortions involves two drugs, mifepristone and misoprostol. The drugs can be taken at home and are used in just over half of U.S. abortions.

Mifepristone dilates the cervix and blocks the action of the hormone progesterone, which enables a pregnancy to continue. Misoprostol causes contractions that empty the uterus. Typically, mifepristone is taken by mouth first, followed by misoprostol a day or two later.

Studies show medication abortions are safe and effective, though with a slightly lower success rate than ones done by procedure in a clinic.

Mifepristone was developed in France in the 1980s as an abortion drug to be used with misoprostol. The FDA approved it in 2000. It’s indicated for use during the first trimester. It’s also approved in the U.S. to treat Cushing’s syndrome, a hormonal disorder.

Misoprostol, which is made by several companies, is approved for treating gastric ulcers. It’s sometimes used in miscarriages to help expel tissue, in addition to its use in abortions.

In countries where mifepristone is banned for abortions, misoprostol alone is often used instead. Some U.S. clinics and telehealth providers also offer misoprostol-only abortions.

In these instances, one four-tablet dose of misoprostol is typically recommended for very early abortions. Additional doses taken four hours apart are recommended for later abortions.

Medication abortions are generally less expensive than procedures. At Carafem, a reproductive health group with clinics in four states and telehealth services in 16 states, medication abortions with both drugs cost $249.

ALLEN G. BREED — THE ASSOCIATED PRESS Bottles of the drug misoprostol sit on a table at the West Alabama Women’s Center in Tuscaloosa on March 15. Misoprostol induces uterus contractions that expel an embryo or fetus and other tissue.