Administration under the tongue (sublingually) of the abortion medication misoprostol is most effective when taken in three hour intervals, but this can cause more side effects than when taken every 12 hours. The vaginal route of administration should be used if 12 hour intervals are preferred. The findings are reported in the latest edition of The Lancet.
The only approved regimen of medical abortion is mifepristone followed by misoprostol, and this is a highly effective termination method. However, in many countries mifepristone is not available, and doctors have been using misoprostol alone. But there is no evidence on the best route or interval of administration of misoprostol in order to achieve complete abortion.
Dr Helena von Herzen, Department of Reproductive Health and Research, World Health Organisation (WHO), Geneva, Switzerland and colleagues did a study of 2,046 women, who were divided into four groups, and received the treatment either vaginally at three or twelve hour intervals; or sublingually at three or twelve hour intervals.
For women taking misoprostol every 12 hours, pregnancy continued in 9% when administered sublingually and 4% when given vaginally. In the three hour groups, the difference was smaller: pregnancy continued in 6% of women given misoprostol sublingually, and 4% when given vaginally.
Pregnancy-related symptoms, such as nausea and vomiting, increased after the first dose of misoprostol, and the frequency and intensity of these symptoms increased if the second dose was given after three hours, regardless of route of administration. However side effects such as pain, diarrhoea, chills and shivering were slightly higher in women who took misoprostol sublingually.
The authors conclude: "Administration interval can be chosen between three hours and 12 hours when misoprostol is given vaginally. If administration is sublingual, 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."
In an accompanying comment, Dr Beverly Winikoff, Gynuity Health Projects, New York, USA and Dr Anne Rachel Davis, Columbia University Medical Center, New York, USA discuss the ethics surrounding different methods for aborting pregnancies and the difficulties this can cause depending on the society and culture in which the woman concerned finds herself.
They conclude: "What we study about abortion medications should be conditioned by exactly where we want to use the information. Although the biology is universal, the practical implications are not, which is further proof that the best choices for abortion services cannot be made on the basis of medical considerations alone.
"No drug development for abortion makes sense without remembering the centrality of the experience for women themselves."