Misoprostol vaginal insert significantly reduces time to delivery in labor induction

FDA Highlights by Bruce Sylvester – Misoprostol vaginal insert used for labor induction has significantly reduced time to vaginal delivery compared with dinoprostone vaginal insert, researchers reported at the European Congress on Intrapartum Care held in Amsterdam in May 2013.

Dinoprostone is the only prostaglandin currently FDA-approved for use in the induction of labor. Misoprostol, a PGE1 analogue which is FDA-approved for prevention of NSAID-induced gastric ulcers, has been used off-label to induce labor.

The authors noted that such use of misoprostol involves breaking up tablets and inserting them intra-vaginally, leading to variable amounts of availability of active drug. The vaginal ring delivery system provides controlled drug-release.

At the European Congress on Intrapartum Care, Deborah Wing, MD, associate clinical professor, of obstetrics & gynecology and director of the Division of Maternal-Fetal Medicine at the School of Medicine of the University of California in Irvine, California, presented data from a phase III study comparing misoprostol 200µg vagina insert (MVI) and dinoprostone (10mg) vaginal insert (DVI).

The researchers enrolled 1358 pregnant women undergoing cervical ripening (modified baseline Bishop score ≤ 4) and induction of labor. They randomized the subjects to receive MVI (n=678) or DVI (n=680) at 35 sites in the US.

They reported a median time to vaginal birth of 21.5 hours (95% CI: 20.0-23.4) with MVI compared to 32.8 hours (95%CI: 30.2-34.9) with DVI, a difference of 11.3 hours.

There was no statistically significant difference in terms of caesarean delivery rates. There were significant differences between MVI and DVI in time to any delivery (18.3 v 27.3 hours), time to onset of active labour (12.1 v 18.6 hours) and proportion of women needing pre-delivery oxytocin (48.1% v 74.1%).

There were no statistically significant differences in overall rates of neonatal treatment-emergent adverse events. Uterine-related adverse events such as tachysystole requiring an intervention were more frequent in the MVI group (13.3% v 4.0%: p< 0.001).

An application for marketing authorization for misoprostol vaginal insert used for labor induction was submitted to the FDA in 2012, and action on the application is pending.