Mifepristone & Misoprostol (RU-486, abortion pill)
This is the most common medical abortion method used worldwide. Mifepristone was recently approved in Canada despite the death of a woman from toxic shock due to her abortion related bacterial infection during a Canadian trial of the drug in 2001 and similar deaths recorded elsewhere.
Mifepristone causes abortion by blocking the action of progesterone. Progesterone prepares the uterine lining for implantation and is essential for maintenance of the pregnancy. Progesterone also suppresses uterine contractions.
Mifepristone causes the uterine lining to break down, resulting in detachment of the embryo from its source of nutrition. It causes the cervix to soften and dilate. It also makes the body release prostaglandins and increases the effects of these prostaglandins in causing the uterus to contract.
Mifepristone/misoprostol abortions are quicker than methotrexate/misoprostol abortions. Both regimens have similar rates of complete abortion, side effects and complications. Serious infection and heavy, prolonged bleeding are the most notable side effects, along with nausea, vomiting, diarrhea and headache.
Methotrexate and Vaginal or Oral Misoprostol
In Canada, methotrexate and misoprostol are used together for medical abortion up to 49 days of pregnancy.
Methotrexate breaks down the cell layer that attaches the embryo to the wall of the uterus, depriving the embryo of essential nutrients and resulting in its death.
Misoprostol is a synthetic prostaglandin that causes the cervix to soften and dilate and the uterus to contract and expel the embryo or fetus.
Abortion with methotrexate and misoprostol requires several clinic visits. During the first visit, methotrexate is injected, followed at 2-7 days with misoprostol pills at home or at a clinic, either inserted into the vagina or taken by mouth. A follow-up visit is required after 1 to 3 weeks to determine if the abortion has occurred.
The methotrexate and misoprostol abortion regimen causes complete abortion in 70-97% of cases. While most of the abortions occur within the first hours or days after taking the misoprostol, 20 to 35% will take up to several weeks. A surgical abortion is scheduled to complete the abortion if it has not occurred by that point because the drugs used can cause birth defects.
Side effects of medical abortion using methotrexate and misoprostol include: significant cramping pain and heavy bleeding during the abortion, along with nausea, vomiting, diarrhea, headache, fever, and chills; prolonged bleeding for one to seven weeks afterwards, and infection; birth defects if the pregnancy is ongoing and the fetus survives.
Misoprostol is a synthetic prostaglandin that causes the cervix to soften and dilate, and the uterus to contract and expel the embryo or fetus. It is used vaginally in abortions up to 56 days since the first day of the last menstrual period.
When used alone, Misoprostol causes complete abortion in 22-94% of cases.
Early side effects are worse with this method than with other methods of medical abortion, and include pain, dizziness, nausea, vomiting, diarrhea, chills and rashes. Heavy and prolonged bleeding and infection are associated with medical abortion in general. Misoprostol is generally used with another drug because of the higher incidence of side effects and lower rate of effectiveness when it is used alone.
Misoprostol is commonly used in surgical abortions as well, to soften and dilate the cervix, and to reduce bleeding.