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Contraception. 1997 Dec;56(6):367-71.

Medical abortion with methotrexate 75 mg intramuscularly and vaginal misoprostol.

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Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee-Womens Hospital, PA 15213-3180, USA.


Methotrexate (50 mg/m2 intramuscularly and 50 mg orally) followed by vaginal misoprostol have proven to be > 90% effective at causing abortion in women at less than 49 days' gestation. Although the effectiveness of the oral dose (which has a lower serum bioavailability) demonstrates that a methotrexate dose of 50 mg/m2 may be more than necessary, an intramuscular regimen is more advantageous because it is less costly. This trial was designed to investigate the potential effectiveness of a single dose of methotrexate, 75 mg intramuscularly, in a regimen for early abortion. One hundred subjects received 75 mg methotrexate intramuscularly followed 5 to 6 days later by 800 micrograms misoprostol vaginally. The misoprostol dose was repeated if the abortion did not occur. 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 abortion occurred in 94 of 99 (94.9%, 95% CI 90.6, 99.3%) patients. The complete abortion rate was no different for earlier gestations: 38 of 40 (95.0%, 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). Abortion occurred in the 24 h following the initial or repeat misoprostol dose (immediate success) in 70.7%; the remaining 24.2% of women who aborted did so after a delay of 22 +/- 10 days (mean + standard deviation). Vaginal bleeding lasted 17 +/- 8 days and 11 +/- 7 days in immediate 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 methotrexate intramuscularly appears to have similar effectiveness to one with 50 mg/m2 methotrexate.


The effectiveness for early abortion of a single dose (75 mg intramuscularly) of methotrexate, followed 5-6 days later by 800 mcg of misoprostol vaginally, was investigated in 99 women presenting to a Pittsburgh, Pennsylvania (US), hospital with pregnancies under 50 days' gestation. Complete abortion occurred in 94 patients (94.9%). There were no significant differences in this rate by gestation (up to 42 days vs. 43-49 days). In 70 cases (70.7%), abortion occurred in the 24 hours following the initial or repeat misoprostol dose. Overall, 77.8%, 86.9%, and 91.9% of women had expelled the fetus by 14, 28, and 35 days, respectively, after receiving methotrexate. Vaginal bleeding lasted an average of 17 days in women who aborted in 24 hours and 11 days in those with delayed abortion. Side effects associated with methotrexate included nausea (47%), warmth/hot flashes (43%), diarrhea (22%), dizziness (21%), headache (16%), and vomiting (12%). These results are comparable to those obtained with an intramuscular dose of 50 mg/sq. m or an oral dose of 50 mg of methotrexate. The lowest effective dose of methotrexate, when combined with misoprostol for abortion, remains to be determined.

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