Evaluation of Isosorbide Mononitrate for Preinduction of Cervical Ripening: A Randomized Placebo-Controlled Trial.
AbstractObjective:To evaluate the safety and efficacy of Isosorbide mononitrate (IMN) as a cervical ripening agent prior to induction of labour in term pregnant women.Materials and methods: A randomized placebo-controlled study was conducted on 100 term singleton pregnancies planned for induction of labour. The participants were randomly assigned to two groups. One group received 40 mg IMN and the other group received 40mg of placebo kept vaginally. The main outcome of this study was to evaluate the efficacy of IMN in cervical ripening based on the change in modified Bishop score and the effect on time duration between the drug insertion and delivery. Safety of isosorbide mononitrate was assessed by measuring variables related to maternal and neonatal outcomes.Results:Baseline demographic characteristics were similar in both groups. The mean change in modified Bishop score after 2 doses of 40mg IMN was insignificant when compared to placebo. Though IMN shortened the time duration between the drug insertion to delivery when compared to placebo, it was statistically insignificant. The need for oxytocin and 2(nd) ripening agent was less in IMN group when compared to placebo group but statistically this also proved to be insignificant. It was noted that there was an increase in caesarean deliveries in IMN than in placebo group. IMN did not cause any significant change in maternal hemodynamics and adverse side effects. Though NICU admission and stay was less in IMN than in placebo group, it was statistically insignificant.Conclusion:Though IMN did not cause any maternal and neonatal adverse effects, it was found to be inefficient in comparison to placebo as a cervical ripening agent.
Cunningham FG, Leveno KT, Bloom SL, Hauth JC, Rouse DJ, Spong CY. Labor induction. Williams Obstetrics. 23rd ed. New York: McGraw-Hill Medical, 2010.
Chwalisz K, Garfield RE. Nitric oxide as the final metabolic mediator of cervical ripening. Hum Reprod 1998; 13: 245-8.
Edwards RK, Richards DS. Preinduction cervical assessment. Clin Obstet Gynecol 2000; 43: 440-6.
Bollapragada SS, MacKenzie F, Norrie JD, Eddama O, Petrou S, Reid M, et al. Randomised placebo-controlled trial of outpatient (at home) cervical ripening with isosorbide mononitrate (IMN) prior to induction of labour--clinical trial with analyses of efficacy and acceptability. The IMOP study. BJOG 2009; 116: 1185-95.
Osman I, MacKenzie F, Norrie J, Murray HM, Greer IA, Norman JE. The "PRIM" study: a randomizedcomparison of prostaglandin E2 gel with the nitric oxide donor isosorbide mononitrate for cervical ripening before the induction of labour at term. Am J Obstet Gynecol 2006; 194: 1012-21.
Agarwal K, Batra A, Batra A, Dabral A, Aggarwal A. Evaluation of isosorbide mononitrate for cervical ripening prior to induction of labor for post-dated pregnancy in an outpatient setting. Int J Gynaecol Obstet 2012; 118: 205-9.
Habib SM, Emam SS, Saber AS. Outpatient cervical ripening with nitric oxide donor isosorbide mononitrate prior to induction of labor. Int J Gynaecol Obstet 2008; 101: 57-61.
Bullarbo M, Orrskog ME, Andersch B, Granström L, Norström A, Ekerhovd E. Outpatient vaginal administration of the nitric oxide donor isosorbide mononitrate for cervical ripening and labor induction post term: a randomized controlled study. Am J Obstet Gynecol 2007; 196: 50. e1-5.
Ekerhovd E, Brännström M, Delbro D, Norström A. Nitric oxide mediated inhibition of contractile activity in the human uterine cervix. Mol Hum Reprod 1998; 4: 915-20.