Randomized trial of isosorbide mononitrate versus misoprostol for cervical ripening at term.
OBJECTIVE
To assess the adverse effects of isosorbide mononitrate (IMN) compared with misoprostol for cervical ripening at term.


METHODS
One hundred and seven women with term pregnancies referred for induction of labor with Bishop scores of 6 or less were randomly allocated to receive either a 40-mg IMN tablet vaginally (n = 55) or 50 microg misoprostol vaginally (n = 52) every 6 h for a maximum of three doses. They were sent to the labor ward for amniotomy or oxytocin if either their Bishop scores were more than 6 or their cervices were not ripe 24 h after the treatment. Adverse effects, progress, and outcomes of labor were assessed.


RESULTS
Isosorbide mononitrate was associated with fewer adverse effects especially uterine tachysystole (0 vs. 19.2%, P < 0.01) and hyperstimulation (0 vs. 15.4%, P < 0.01). The time from start of medication to vaginal delivery in IMN group was significantly longer (25.6 +/- 6.1 vs. 14 +/- 6.9 h, P < 0.01). Oxytocin was needed in 51 women (92%) of the isosorbide mononitrate group and six women (11%) of the misoprostol group (P < 0.001). The cesarean rate was not significantly different between the groups, but the major indications were different: dystocia (45%) in the IMN group vs. persistent non-reassuring fetal heart rate pattern (56%) in the misoprostol group.


CONCLUSIONS
Cervical ripening with IMN resulted in fewer adverse effects, but was less effective than misoprostol.
Chanrachakul
B
B
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynaecology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. mgxbc@nottingham.ac.uk
Herabutya
Y
Y
Punyavachira
P
P
D000328:Adult; D020070:Cervical Ripening / Q000187:drug effects*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007548:Isosorbide Dinitrate / Q000009:adverse effects* / Q000031:analogs & derivatives*; D016595:Misoprostol / Q000009:adverse effects*; D007744:Obstetric Labor Complications / Q000175:diagnosis*; D010120:Oxytocics / Q000009:adverse effects*; D011247:Pregnancy; D011256:Pregnancy Outcome; D013997:Time Factors; D014599:Uterus / Q000187:drug effects; D014665:Vasodilator Agents / Q000009:adverse effects*
D010120:Oxytocics; D014665:Vasodilator Agents; D016595:Misoprostol; D007548:Isosorbide Dinitrate; C030397:isosorbide-5-mononitrate