Isosorbide Mononitrate a Nitric Oxide Donor: A Study of Its Efficacy and Safety as an Agent for Cervical Ripening.

OBJECTIVE To study the efficacy and safety profile of isosorbide mononitrate (IMN) as an agent for cervical ripening. METHODOLOGY This study was conducted in the Department of Obstetrics and Gynecology, M Y Hospital & M G M Medical College Indore from September 2011 to February 2013. Pregnant women attending the antenatal clinics were screened for possible participation in the study after explaining the nature of the study. This study was conducted on 150 patients. An initial dose of 40 mg IMN was applied in the posterior vaginal fornix, and the same dose was repeated after 6 h. Cervical ripening was assessed by the change in Bishop Score 12 h after the initial application. RESULTS In a study of 150 cases, mean maternal age was 22.2 ± 2.6 years (range 19-35 years) and mean gestational age was 40.5 ± 1.07 (range 40-42 weeks). 52 women were primigravidas, while 98 were multigravidas. The mean Bishop Score-before drug administration was 1.94 ± 1.3 (range 0-5), and mean fetal heart rate was 137 ± 6.2 bpm. The mean of Bishop scores before IMN administration was 1.94 ± 1.3, while mean of Bishop score after drug administration was 6.7 ± 2.2; mean difference was equal to 4.76. P value was equal to 0.0001. By conventional criteria, this difference is considered to be statistically significant. The mode of delivery 96 (64 %) delivered vaginally, while 54 (36 %) were delivered by Cesarean section. Mean Apgar score at 1 min was 8.2 ± 0.9 SD (range 7-10), while mean Apgar score at 5 min was 9.4 ± 0.6 (range 8-10). The only side effect noted was headache, and 30 cases (20 %) complained of headache. CONCLUSION IMN seems to be effective, safe, inexpensive, and well-tolerated agent for cervical ripening. It is cost effective and safe with minimal side effects.