The efficacy of intravenous hyoscine-n-butylbromide for the acceleration of labour in primiparous women: a randomised controlled trial

Abstract

Background: Antispasmodic agents have been used to hasten labour despite little high-quality evidence to support their efficacy.

Objective: To establish the safety and efficacy of hyoscine-N-butylbromide in accelerating labour in primiparous women.

Methods: A randomised, double-blinded, placebo-controlled clinical trial was conducted at the Aga Khan University Hospital Nairobi, Kenya. Consenting primiparous women in spontaneous labour at term were randomised to receive either 40mg of hyoscine-N-butylbromide or sterile water-for-injection intravenously once confirmed to be in active labour. The dose could be repeated once after four hours. The main outcome measure was the duration of labour. Secondary outcome measures were rate of cervical dilatation and postpartum satisfaction score. Safety aspects such as drug adverse effects, APGAR scores and postpartum hemorrhage were also explored.

Results: Between October 2009 and July 2010 a total of 85 women were randomised and 79 yielded data for analysis. Of these 37 received hyoscine-N-butylbromide and 42 received placebo. There was no significant difference in the mean duration of active labour to second stage between the drug and placebo arms (396.2 versus 389.3 minutes, respectively, p=0.881, 95% CI -85.9 to 99.8). The mean rate of cervical dilatation in the drug arm was 1.17 centimetres per hour (cm/hr) compared to 1.22cm/hr in the placebo arm. This difference was not statistically significant (p value=0.832). The postpartum satisfaction scores were similar between the two arms. Hyoscine-N-butylbromide was well tolerated without any major adverse effects observed in either arm.

Conclusion: Hyoscine-N-butylbromide does not shorten the duration of labour in first time parturients in spontaneous labour. It also does not change maternal satisfaction with care received and is not associated with major adverse outcomes in the mother or newborn.

Keywords: Antispasmodics, Hyoscine-N-butylbromide, Labour