MEDICAL ABORTION WITH METHOTREXATE 75 MG INTRAMUSCULARLY AND VAGINAL MISOPROSTOL

Methotrexate (50 mg/m(2) intramuscularly and 50 mg orally) followed by vaginal misoprostol have proven to be > 90% effective at causing abor tion in women at less than 49 days' gestation. Although the effectiven ess of the oral dose (which has a lower serum bioavailability) demonst rates that a methotrexate dose of 50 mg/m(2) may be more than necessar y, an intramuscular regimen is more advantageous because it is less co stly. This trial was designed to investigate the potential effectivene ss of a single dose of methotrexate, 75 mg intramuscularly, in a regim en for early abortion. One hundred subjects received 75 mg methotrexat e intramuscularly followed 5 to 6 days later by 800 mu g misoprostol v aginally. The misoprostol dose was repeated if the abortion did not oc cur. Outcome measures included successful abortion (complete abortion without requiring a surgical procedure), duration of vaginal bleeding, and side effects. One subject was lost to follow-up. Complete abortio n occurred in 94 of 99 (94.9%, 95% CI 90.6, 99.3%) patients. The compl ete abortion rate was no different for earlier gestations: 38 of 40 (9 5.0%, 95% CI 88.2, 100%) at up to 42 days' gestation and 56 of 59 (94. 9%, 95% CI 89.3, 100%) at more than 42 days' gestation (p = 0.99). Abo rtion occurred in the 24 h following the initial or repeat misoprostol dose (immediate success) in 70.7%; the remaining 24.2% of women who a borted did so after a delay of 22 +/- 10 days (mean + standard deviati on). Vaginal bleeding lasted 17 +/- 8 days and 11 +/- 7 days in immedi ate success and delayed success patients, respectively. Overall, 77.8% , 86.9%, and 91.9% of patients had passed the pregnancy by 14, 28, and 35 days, respectively, after receiving methotrexate. This preliminary evaluation demonstrates that a medical abortion regimen using 75 mg m ethotrexate intramuscularly appears to have similar effectiveness to o ne with 50 mg/m(2) methotrexate. (C) 1997 Elsevier Science Inc. All ri ghts reserved.