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Study Finds Lower Dose of Mifepristone Still Effective When Used With Misoprostoli Early Termination of Pregnancy

PITTSBURGH, August 31, 2001 — A 100-milligram dose of mifepristone may be an effective alternative to larger doses of the drug when used with misoprostol for early pregnancy termination, according to the results of a recent study published in the September issue of Obstetrics and Gynecology.

Previously, dosages of mifepristone given to women have ranged from 200 to 600 milligrams.

Sold under the name Mifeprex®, mifepristone was approved by the U.S. Food and Drug Administration in September for use in the United States. The drug is commonly known in Europe as RU-486, or the abortion pill. It is part of a regimen prescribed by doctors in many countries that includes misoprostol, an ulcer drug.

“The long-term benefit of the study shows that a lower effective dose of mifepristone could lower overall cost of treatment,” said Mitchell Creinin, M.D., lead study author and director of family planning in the department of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine. “Most importantly, this information provides more knowledge for future developments of antiprogestins.”

In addition to Dr. Creinin, study authors include Helen C. Pymar, M.D. and Jill L. Schwartz, M.D.

Mifepristone blocks the hormone progesterone, which is necessary for an established pregnancy to continue. Misoprostol causes the uterus to contract and expel the fetus. The drug combination was approved in 1988 for use in France as an abortifacient. It has been used in Britain since 1991, and Sweden since 1992. It is only effective early in pregnancy, usually within the first 49 days.

In the study, 80 women were given 100-milligram doses of mifepristone, followed 48 hours later by the administration of misoprostol in either a dose of 400 micrograms orally or 800 micrograms vaginally. Participants returned for evaluation approximately 24 hours following use of misoprostol, and then again two to three weeks later.

In the 24 hours following administration of misoprostol, a majority of women – 72 out of 80 – had experienced complete abortions. Four women who had received a 400-microgram dose of misoprostol orally required a surgical abortion after two weeks. None of those who received an 800-microgram dose of misoprostol vaginally required further intervention.

Side effects, mainly nausea, vomiting, cramping and diarrhea, were comparable for both groups. Dr. Creinin notes that women who suffer spontaneous abortion, or miscarriage, early in pregnancy suffer similar symptoms. Many participants reported that pain was manageable by using nonprescription painkillers such as ibuprofen or acetaminophen.

“This study suggests that both regimens tested in this trial, using a mifepristone dose of 100 milligrams, provides clinical efficacy in the same range as regimens using higher doses,” wrote Dr. Creinin. “Prospective trials are needed to find the mifepristone and misoprostol regimen with the most acceptable side-effect profile.”

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