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U.S. Mifepristone Clinical Trial: Summary of Findings

Early pregnancy termination with mifepristone and misoprostol in the United States, Irving M. Spitz, M.D. D.Sc., C. Wayne Bardin, M.D., Lauri Benton, M.D., and Ann Robbins, Ph.D., New England Journal of Medicine, April 30, 1998 and

Acceptability and feasibility of early pregnancy termination by mifepristone-misoprostol: Results of a large multi-center trial in the United States, Beverly Winikoff, M.D., M.P.H., Charlotte Ellertson, Ph.D., Batya Elul, M.Sc., and Irving Sivin, M.A., Archives of Family Medicine, July/August 1998


The U.S. study of mifepristone medical abortion was a success:


Goals of the U.S. clinical trials

The U.S. trials were conducted:

Sites and women were diverse and inclusive

Medical abortion can be provided safely and well in the U.S.

Efficacy results up to 49 days with mifepristone and misoprostol are comparable to other studies

Side effects are similar to a natural miscarriage

Women were highly satisfied with the procedure

Rigorous definition of failure affected study results

We had a rigorous definition of failure. We considered the method a failure if a woman chose to try medical abortion but then had a surgical intervention during the study period-for any reason at all. In other words, success meant no surgery during the study period. Failure under this definition resulted if a surgical procedure was used for any of these reasons:

Provider experience is key to successful outcome

The various studies of the mifepristone-misoprostol regimen produce different rates of success and failure. Why might the success rate from this U.S. clinical trial be somewhat lower than the results from the latest French study? The drug combination is the same; the difference may lie in the providers' experience. Although this study was not designed to test whether success rates improved with provider experience, clinicians associated with the trial report that their success rate increased as they became more comfortable with the method.


General Information about Mifepristone in the United States

Were any U.S. government funds used for this project?

No government funds were used for these trials or any other part of the project.

What does the approval process involve?

The U.S. rights were donated to the Population Council in May 1994. Our clinical trial started in September 1994 and concluded a year later. The 164-volume NDA, which was submitted in March 1996, was based on data from the French pivotal studies, which we translated, audited, and re-analyzed. In July, after a public hearing, an FDA advisory committee recommended that the FDA approve use of mifepristone for medical abortion. The FDA issued an approvable letter in September 1996, saying that mifepristone was safe and effective, but that the Council needed to provide additional information on labeling and manufacturing. Since then, we have given the agency revised labeling and four volumes with the U.S. clinical trial data. In June 1997, we gave the FDA a safety update on all worldwide experience on the use of mifepristone for all indications. Additional information on manufacturing still has to be provided before the drug can be approved

Is it unusual for the FDA to approve a drug based on data from other countries?

No. The FDA routinely approves drugs already approved by regulatory agencies in Europe. The New Drug Application for mifepristone was based on good-quality French studies and extensive additional data from Europe and around the world. The FDA requires NDA sponsors (the Council in this case) to provide all information related to safety regardless of the geographic source.

When will mifepristone be available in the U.S.?

Our licensee, The Danco Group, has said it expects the drug to be approved and available in 1999.

How much will the mifepristone-misoprostol regimen cost when it is available?

It is not yet possible to determine the cost. In general use, we believe the cost of medical abortion will be comparable to surgical abortion. The cost of the pills themselves is only one factor in overall cost determination. Our distributor also plans to make the drug accessible to women with limited financial resources through Medicaid where available.

Who will be able to provide mifepristone?

Any properly trained provider, working in a hospital, clinic, or office setting, with access to backup facilities for treating incomplete abortion and medical emergencies, will be able to provide mifepristone. Providers must be able to date a pregnancy and detect an ectopic pregnancy. Mifepristone will not be available at commercial pharmacies.

Will young women have access to this drug?

Once it is approved by the FDA, physicians will be able to prescribe the drug for women of any age who do not have medical contraindications to it, in accordance with state laws.

Will availability of mifepristone eliminate the need for surgical abortion?

Mifepristone is effective only during early pregnancy. Surgical abortion will still be needed for the small number of cases where mifepristone fails; for later abortions; and as an option for women who prefer it.

How will mifepristone change the abortion picture?

Abortion may be more accessible and more private. We expect that women will be able to locate providers closer to their homes who are willing to provide nonsurgical abortions. Eventually, women obtaining medical abortions may have greater privacy than women undergoing surgical abortions. In addition, over time, women will become more accustomed to seeking their abortions earlier in pregnancy. We do not anticipate an increase in the number of abortions; in France, for example, the total number of abortions per year has not increased since the method was introduced in 1989.


    The Population Council is a nonprofit, nongovernmental institution that seeks to improve the wellbeing and reproductive health of current and future generations around the world and to help achieve a humane, equitable, and sustainable balance between people and resources. The Council conducts biomedical, social science, and public health research and helps build research capacities in developing countries. Established in 1952, the Council is governed by an international board of trustees. Its New York headquarters supports a global network of regional and country offices

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