A Prospective Randomized Comparison Trial on the Use of Mifepristone With Sublingual or Buccal Misoprostol for Medical Abortions of Less Than 9 Weeks Gestation

After mifepristone was approved by the United States Food and Drug Administration in 2000, the combination of mifepristone 200 mg and vaginal use of misoprostol 800 mcg became almost a standard of care in early medical abortion up to 63 days of gestation. When combined with mifepristone for medical abortion in the first trimester, vaginal administration of misoprostol is more effective, faster, and has a lower rate of ongoing pregnancy, and fewer gastrointestinal side effects than oral misoprostol.

Although misoprostol is more effective when given vaginally, most women prefer the oral route because this can avoid the uncomfortable vaginal examination and provide more privacy during medical induction. Another concern about vaginal administration is the potential risk of infection. In late March 2006, analyses of serious uterine infections following medical abortions by a regimen of oral mifepristone followed by vaginal misoprostol led Planned Parenthood Federation of America health centres to change the route of misoprostol administration. Given these concerns, alternative administration via sublingual (holding pills under the tongue) and buccal (holding pills in the cheek) routes have been investigated, as the misoprostol is absorbed directly and avoids the gastrointestinal system similar to vaginal administration.

A pharmacokinetic study showed that sublingual administration of misoprostol resulted in the greatest bioavailability when compared with oral or vaginal administration. In a randomized, cross-over pharmacokinetic study of 10 women by Schaff and colleagues of sublingual versus buccal misoprostol 800 mcg, the mean misoprostol plasma concentration-time curves at 4 hours and the maximum concentration were significantly higher for sublingual administration than the buccal route. However, buccal misoprostol administration resulted in fewer symptoms and was found to be more acceptable by women.

Buccal misoprostol 800 mcg after mifepristone 200 mg for terminating pregnancy through 63 days of gestation has a higher success rate and less ongoing pregnancy when compared with oral misoprostol, especially in pregnancies of 57-63 days. Adverse effect profiles were similar, although fever and chills were reported approximately 10% more often among women who took buccal misoprostol. When used for abortion through 56 days of gestation, buccal administration of misoprostol after mifepristone appears to be a highly effective and acceptable alternative compared with vaginal administration, and with similar adverse effects profile.

Medical abortions of less than 9 weeks gestation using sublingual misoprostol 800 mcg after mifepristone 200 mg has achieved complete abortion rate of 98.2% but is associated with more gastrointestinal side effects, fever, and chills when compared with vaginal route.

Both buccal and sublingual administration of misoprostol following mifepristone have been shown to be effective in inducing first trimester medical abortions, but with different side effects profile. No clinical trials have been conducted comparing buccal and sublingual administration of misoprostol in first trimester medical abortion. The purpose of the present study is to compare the incidence of side effects of buccal and sublingual misoprostol when combined with mifepristone.