Papaverine prior to catheter balloon insertion for labor induction: a randomized controlled trial

BACKGROUND: Catheter balloon insertion is a common method for cervical ripening and labor induction. Papaverine and its derivatives are musculotropic antispasmodic drugs that directly induce smooth muscle relaxation. Used during childbirth, these drugs have been suggested to shorten the duration of labor. OBJECTIVE: This study aimed to evaluate the effect of administering papaverine before catheter balloon insertion on changes in Bishop scores and on the labor induction–to–delivery interval. STUDY DESIGN: This randomized, double-blinded, placebo-controlled trial was conducted in a single tertiary university-affiliated hospital. Participants were admitted at term for labor induction with an initial Bishop score of ≤6. Participants were randomized to receive 80 mg intravenous papaverine or 0.9% normal saline solution within 30 minutes of Foley catheter balloon insertion. The co-primary outcomes were the difference in Bishop score from before catheter balloon insertion to after removal and the labor induction–to–delivery interval. The secondary outcomes included maternal pain and satisfaction scores, delivery within 24 hours, and neonatal outcomes. Both intention-to-treat and per-protocol analyses were performed. RESULTS: Overall, 110 women were enrolled. In the intention-to-treat analysis, the median difference in Bishop score was greater in the papaverine group than in the placebo group (5 [interquartile range, 1-11] vs 4 [interquartile range, 0-7], respectively; P=.025), and the median catheter balloon insertion–to–delivery interval was shorter in the papaverine group than in the placebo group (21 hours [interquartile range, 6–95] vs 26 hours [interquartile range, 3–108], respectively; P=.031). A higher proportion of women delivered within 24-hours in the papaverine group than in the placebo group (65.5% vs 41.8%, respectively; P=.012). Pain and satisfaction scores, delivery, and neonatal outcomes were similar between the groups. Similar results were found in the per-protocol analysis. CONCLUSION: Papaverine administration before Foley catheter balloon insertion for cervical ripening resulted in improved Bishop scores and shorter catheter balloon insertion–to–delivery intervals.