Simultaneous Administration Compared With a 24-Hour Mifepristone-Misoprostol Interval in Second-Trimester Abortion: A Randomized Controlled Trial

Abstract

Objective: To compare outcomes with simultaneous administration of mifepristone and misoprostol with a regimen in which the drugs are administered at a 24-hour interval for second-trimester abortion.

Methods: In this placebo-controlled, double-blind trial, participants were randomized to receive mifepristone either 24 hours before or at the same time as misoprostol. Participants were hospitalized to receive 400 micrograms buccal misoprostol at 3-hour intervals up to 48 hours or until uterine expulsion. The primary outcome was the proportion of women who experienced uterine expulsion within 24 hours after the first misoprostol dose and this required 504 women to examine our hypothesis that this rate would be 85% in the 24-hour interval arm compared with 70% in the simultaneous arm. Secondary outcomes included total abortion time from mifepristone and misoprostol.

Results: From February 2013 to April 2014, 509 women were enrolled. Women in the 24-hour interval arm were more likely to abort within 24 hours (94.4% compared with 85.0%, relative risk 1.11, 95% confidence interval [CI] 1.05-1.18). At 48 hours, the rate was similar in the two arms (96.8% [24-hour interval] and 95.7% [simultaneous], relative risk 1.01, 95% CI 0.97-1.04). Median misoprostol dosing time was shorter in the 24-hour interval arm (7.7 compared with 13 hours; P<.001) and consistent with the median misoprostol doses required (three compared with five; P<.001). Median time from mifepristone to uterine expulsion was longer in the 24-hour interval arm (32.3 compared with 13 hours; P<.001). Both regimens had high acceptability rates and reported similar side effects and pain scores.

Conclusion: Administering mifepristone and misoprostol simultaneously results in lower expulsion rates within 24 hours of taking misoprostol, longer median misoprostol treatment times, and requires more misoprostol doses. At 48 hours, both regimens work equally well. Simultaneous dosing results in less total time from the first clinical contact to complete abortion.

Clinical trial registration: ClinicalTrials.gov, https://clinicaltrials.gov, NCT01768299.