What Is the Connection between Mifepristone and Misoprostol?

Mifepristone and misoprostol are connected because together they are used to produce medical abortions for women who are less than eight weeks pregnant. The drugs are not identical and perform different actions. Mifepristone, often known by its manufacturing name RU-486™, is almost always used for abortion or to end missed miscarriages. Misoprostol has wider applications and may be used in place of prostaglandins to create cervix softening prior to birth. It can also help prevent stomach ulcers that are caused when people take non-steroidal anti-inflammatory drugs (NSAIDS).

In early pregnancy, defined as eight weeks or less, a medical abortion typically requires mifepristone and misoprostol. Women use an oral dose of mifepristone first, followed by either an oral or vaginal suppository dose of misoprostol several hours later. In slightly over 90% of women, this induces abortion within two days, provided it is used in early pregnancy. Misoprostol becomes increasingly less effective in more advanced pregnancies, and other, more effective drugs may be chosen for pregnancies that are at least eight weeks along.

The different actions of mifepristone and misoprostol explain their effectiveness in inducing abortion. Mifepristone works to separate the placenta from the uterine lining, and it causes uterine contractions. Additionally, the drug has some effect on the cervix and may cause it to soften.

Misoprostol increases cervix softening, especially when used in a suppository form. It also stimulates greater uterine contractions. The combined action of the two drugs terminates the pregnancy, in most cases. Occasionally, the medications do not work, and a surgical abortion is necessary.

Mifepristone and misoprostol can also be connected by the side effects they produce together. Both are likely to cause symptoms of miscarriage like bleeding, cramping, and fatigue. They may also result in shaking, vomiting, and diarrhea. Though these drugs combined represent a way to avoid a surgical abortion, a person using them together should consider having a family member or friend provide support while they are used, as strong feelings of discomfort and illness may occur.

There are some differences between mifepristone and misoprostol. Though both drugs may be used in abortion, misoprostol has some related and unrelated uses. As mentioned, the drug can be used to soften the cervix, since it is a synthetic prostaglandin. This softening may be especially important for women who are undergoing an induced labor. It can improve how quickly and effectively other drugs like pitocin work.

Additionally, misoprostol has a use that is completely unrelated to reproduction. It can effectively prevent gastric ulcers from forming in patients who must use NSAIDs. Unlike misoprostol, mifepristone is not known to have applications except as an abortifacient. It is worth mentioning that women who are pregnant or plan to get pregnant should avoid using misoprostol for ulcer prevention, since it can cause miscarriage.