Background: Misoprostol and Isosorbide Mononitrate have emerged as potential options for inducing medical abortions and promoting cervical ripening, with Misoprostol being a prostaglandin E1 analogue known for its effectiveness in various obstetric applications, and Isosorbide Mononitrate showing promise in this context. The present study aimed to compare the effects of vaginal misoprostol versus isosorbide mononitrate on cervical ripening in induction for first-trimester missed abortion.

Subjects and methods: This prospective randomized interventional study was carried out on 58 patients with missed abortions divided into two groups: Group A, comprised 29 patients who received vaginal misoprostol (800 μg every 8 hours, 2400mg per day), and Group B, consisting of 29 patients who received 80 mg isosorbide mononitrate vaginally, repeatable every 6 to 12 hours if needed, up to 320mg per day. Induction to abortion interval, abortion timing, in addition to side effects were evaluated among the two studied groups.

Results: The mean induction to abortion interval in Group A was significantly less than in Group B (17.25 ± 2.41 hours vs. 27.7 ± 1.77 hours). Significantly more patients in Group A experienced successful abortions within 24 hours (68.97%) and 48 hours (89.66%) compared to Group B (31.03% and 65.52%, respectively).

Conclusion: Misoprostol demonstrated superiority in several key aspects. It aided in the significantly higher rate of complete abortions, achieved a faster induction to abortion interval, and resulted in more successful abortions within 24 and 48 hours of administration.