RESUMO
Background: Drotaverine, a spasmolytic, has been found to have potential to achieve a reduction in the duration of labor and prevent prolonged labor. Objective: To compare the effects of intravenous drotaverine hydrochloride with placebo for shortening the duration of active phase of labor in primigravida's. Methods: A double-blind, placebo-controlled randomized trial of 246 primigravida's in active phase of labor at term was conducted. They were randomly (1:1 ratio) administered intravenous 2 ml (40mg) of drotaverine hydrochloride or 2 ml of Vitamin B complex as placebo. The primary outcome measure was the duration of active phase of labor. The secondary outcome measures were cervical dilatation rate, oxytocin augmentation rate, incidence of prolonged labor, labor pain scores, mode of delivery, maternal and neonatal outcomes. Results: The mean duration of active phase of labor (hour) was significantly lower in the drotaverine group compared to the control (drotaverine; 6.22 ± 2.41 vs placebo; 8.33 ± 3.56; p <0.001). Also, the cervical dilatation rate (cm/hr) was significantly faster in the drotaverine arm (drotaverine; 1.68 ± 1.02 versus placebo; 1.06 ± 0.53, p <0.001). There was a significantly higher probability of faster delivery among women who were given drotaverine (log-rank test, p < 0.001). The oxytocin augmentation rate, incidence of prolonged labor, labor pain scores, mode of delivery, maternal and neonatal outcomes were not significantly different among the groups. Conclusions: Drotaverine hydrochloride is effective in shortening the duration of active phase of labor without adverse maternal and neonatal outcomes. However, more evidence is needed to explore its role in active phase of labor among primigravid women. Trial registration number: PACTR201810902005232