THURSDAY, June 7, 2007 (HealthDay News) -- Taking the abortion drug misoprostol under the tongue is most effective when the doses are taken in three-hour intervals, but this approach can cause more side effects than if the drug is taken in 12-hour intervals, according to a study published Thursday in The Lancet.
If a patient prefers 12-hour intervals, vaginal administration of the drug is the recommended method, the researchers say.
While the use of another drug, mifepristone, followed by misoprostol, is the only approved method of medical abortion in the U.S., there are many countries where mifepristone isn't available and doctors use misoprostol alone to induce abortion, according to background information in the study.
Until now, there hasn't been any evidence about the best method or interval of administering misoprostol alone to achieve complete abortion.
In this study, Dr. Helena von Hertzen, of the Department of Reproductive Health and Research at the World Health Organization, and her colleagues studied 2,046 women who were divided into four groups that received misoprostol either vaginally at three- and 12-hour intervals, or under the tongue at three or 12-hour intervals.
Among women who took misoprostol at 12-hour intervals, pregnancy continued in 9 percent of those who took the drug orally and in 4 percent of those who took it vaginally. Among those who took the drug at three-hour intervals, pregnancy continued in 6 percent of those who took it orally and in 4 percent of those who took it vaginally.
Side effects such as nausea and vomiting were more common among women who took misoprostol under the tongue and vaginally at three-hour intervals than among those who took the drug at 12-hour intervals. Side effects such as pain, diarrhea, chills and shivering were slightly higher among women who took the drug orally.
"Administration interval can be chosen between three hours and 12 hours when misoprostol is given vaginally. If administration is [oral], the intervals between misoprostol doses need to be short, but side effects are then increased. With 12-hour intervals, vaginal route should be used, whereas with three-hour intervals either route could be chosen," the study authors concluded.
More information
MedlinePlus has more about misoprostol.
