A randomized comparison of misoprostol 6 to 8 hours versus 24 hours after mifepristone for abortion

To demonstrate equivalence between mifepristone 200 mg followed 6 to 8 hours later and 24 hours later by misoprostol 800 microg vaginally for abortion in women up to 63 days of gestation.

Mifepristone 200 mg was swallowed by 1,080 women after which they were randomly assigned to self-administer misoprostol intravaginally 6 to 8 hours later (group 1) or 23 to 25 hours later (group 2) at home. Participants returned for an evaluation, including transvaginal ultrasonography, 7 +/- 1 days after initiating treatment. Subjects who had not aborted were offered a second dose of misoprostol. All participants returned approximately 2 weeks after receiving mifepristone. Telephone contact was also attempted approximately 5 weeks after treatment. Treatment was considered a failure if a suction aspiration was performed for any indication.

Complete abortion rates for groups 1 and 2 were 503 of 525 (95.8%, 95% confidence interval 93.7%, 97.3%) and 521 of 531 (98.1%, 95% confidence interval 96.6%, 99.1%), respectively, which were statistically equivalent. Side effects were significantly more common after mifepristone administration for women in group 2. Nausea, vomiting, and heavy bleeding were also significantly greater for women in group 2 after misoprostol treatment. Pain and subject acceptability were similar between groups.

Mifepristone 200 mg followed 6 to 8 hours later by misoprostol 800 microg vaginally is as effective for abortion and has significantly fewer side effects as compared with regimens using a 24-hour dosing interval. Women receiving mifepristone and vaginal misoprostol for abortion can have the flexibility to administer the misoprostol as soon as 6 hours after using the mifepristone.