A comparison of isosorbide mononitrate, misoprostol, and combination therapy for preinduction cervical ripening at term: a randomized controlled trial

Abstract

AimThe purpose of this study was to compare the efficacy, safety, and acceptability of isosorbide mononitrate (IMN), misoprostol, and combination therapy for cervical ripening before induction of labor at term.Patients and methodsA prospective, double-blind, placebo-controlled, randomized clinical trial was carried out on 196 term and post-term nulliparous women with unfavorable cervices who were assigned randomly to receive either 40 mg of IMN (n = 65), 50 ΅g of misoprostol (n = 65), or both of them (n = 66) in the posterior vaginal fornix. Changes in the Bishop score and cervical length, progress, and outcomes of labor and adverse effects were assessed.ResultsCombination therapy was more effective than IMN or misoprostol alone. Successful induction (vaginal delivery within 24 h of initiation of cervical ripening) was significantly higher in the misoprostol (60%) and the combination therapy (62.1%) groups compared with the IMN (27.7%) group (P < 0.0001). The mean duration (h) from treatment initiation to delivery was greater for IMN (26.7 ΁ 7.5) than for misoprostol (16.5 ΁ 6.7) and combination therapy (14.8 ΁ 6.2) groups (P < 0.0001). Oxytocin was needed more in the IMN group (93.8%) than in the misoprostol (21.5%) and combination therapy (25.8%) groups (P < 0.0001). IMN was safer and more acceptable than misoprostol and combination therapy. The cesarean rate was not significantly different among groups, but the major indications were different: dystocia (54.5%) in the IMN group versus a persistent nonreassuring fetal heart rate pattern (57.9%) in the misoprostol and (47.6%) the combination therapy groups (P = 0.01).ConclusionCombination therapy was more effective than either IMN or misoprostol alone for preinduction cervical ripening at term. However, IMN was safer, well tolerated, and more acceptable.