Medications Used in Evidence-Based Regimens for Medical Abortion: An Overview

OBJECTIVE: Abortion is one of the most common medical procedures a woman experiences in her lifetime. Even though overall rates of abortion are decreasing slightly, medical abortion rates are expected to increase in Canada following approval by Health Canada of a combination of mifepristone and misoprostol for use in medical abortion. METHODS: We conducted a literature review as part of the development of the 2016 Society of Obstetricians and Gynaecologists of Canada's Clinical Practice Guidelines on medical abortion. We searched the PubMed, MEDLINE, and Cochrane databases for articles published between 1986 and 2015 using the MeSH terms "induced abortion," "medical abortion," "mifepristone," "misoprostol," "methotrexate," and "prostaglandin." Additionally, we reviewed existing international medical abortion guidelines and searched reference lists. RESULTS: The most commonly studied medical abortion regimens are combinations of mifepristone and misoprostol, methotrexate and misoprostol, mifepristone and prostaglandin, and misoprostol only. Each of these regimens is a potential therapeutic choice; the advantages and disadvantages of each regimen are discussed. CONCLUSION: Drugs used for medical abortion are safe; however, clinicians who provide medical abortion and those who provide care to women who have undergone medical abortion should have an understanding of the pharmacokinetics and clinical effects of the medications used to improve outcomes and mitigate risk.