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

Abstract EN

Aim : the purpose of this study was to compare the efficacy, safety, and acceptability of isosorbide mononitrate (IMN), misoprostol, and the combination therapy for cervical ripening before induction of labor at term.

Patients and Methods : A prospective, double-blind, placebo-controlled, randomized clinical trial in 196 term and post-term nulliparous women with unfavorable cervices who were assigned randomly to receive either 40mg of IMN (n = 65), 50p.g of misoprostol (n = 65), or both of them (n = 66) in the posterior vaginal fornix.

Changes in Bishop score and cervical length, progress and outcomes of labor and adverse effects were assessed.

Results : the combination therapy was more effective than IMN or misoprostol.

Successful induction (vaginal delivery within 24 h of initiation of cervical ripening) was significantly higher in the misoprostol (60 %) and combination therapy (62.1 %) groups compared with the IMN (27.7 %) group (P < 0.0001).

Mean duration (h) from treatment initiation to delivery was greater for IMN (26.7 + 7.5) than 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 persistent non-reassuring FHR pattern (57.9 %) in the misoprostol and (47.6 %) in the combination therapy groups (P = 0.01).

Conclusion : the combination 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.