A Cochrane review included 58 studies. Mifepristone (MIF, antiprogesterone) alone is less effective compared to the combined regimen mifepristone/prostaglandin (RR 3.76 95% CI 2.30 to 6.15; effectiveness measure = failure to achieve complete abortion). MIF 600 mg compared to 200 mg in the combined regimen shows similar effectiveness (4 trials, RR 1.07, 95% CI 0.87 to 1.32). Misoprostol (MIS, prostaglandin) administered orally is less effective (more failures) than the vaginal route (RR 3.00, 95% CI 1.44 to 6.24) and may be associated with more frequent side effects such as nausea and diarrhoea. Sublingual and buccal routes were similarly effective compared to the vaginal route, but had higher rates of side effects. Five trials comparing prostaglandin alone to the combined regimen (mifepristone/prostaglandin) reported in all but one higher effectiveness with the combined regimen. In one trial comparing gemeprost 0.5 mg with MIS 800 mcg, MIS was more effective (failure with gemeprost: RR 2.86, 95% CI 1.14 to 7.18). There was no difference in effectiveness with use of a divided dose compared to a single dose of prostaglandin. In the combined regimen methotrexate (MTX)/prostaglandin, there was no statistically significant difference in failure to achieve complete abortion comparing MTX administered intramuscular to oral (RR 2.04, 95% CI 0.51 to 8.07). Similarly, early (day 3) vs late (day 5) administration of prostaglandin showed no significant difference (RR 0.72, 95% CI 0.36 to 1.43). One trial compared the effect of tamoxifen vs methotrexate and no statistically significant differences were observed in effectiveness between the groups.
A systematic review including 54 studies with more than 32 000 subjects was abstracted in DARE. The review covered wither mifepristone (MIF, 200 to 600 mg) or methotrexate (MTX, 25 to 75 mg/m2) in combination with a prostaglandin analogue, i.e. misoprostol (MIS, 200 to 800 µg) or non-MIS. The three regimens had similar success rates within the gestational age groups of at most 49 days (94 to 96%) and 50 to 56 days (91%). For gestational age of at least 57 days, MIF with MIS had a lower success rate (85%) than MIF with other agent (95%); there were no studies for MTX with MIS. Success was also similar (94 to 96%) for the studies with unspecified gestational age. There were not direct comparisons between MIF-MIS and MTX-MIS. Protection against ectopic pregnancy favours MTX.