Efficacy of hyoscine butylbromide and promethazine on the labor's active phase duration: a systematic review and meta-analysis of randomized controlled trials

 There are different types of drugs to shorten prolonged labor. Spasmolytic drugs are used frequently in the delivery section to overcome cervical spasms and reduce the duration of labor. The study's objective was to evaluate the therapeutic efficacy of hyoscine N-butyl bromide (HBB) and Promethazine on the duration of the active phase of labor.

We searched the Science Direct, PubMed Scopus, Google Scholar, MEDLINE, Web of Science, Cochrane Library, PsycINFO, and ProQuest databases, and reviewed the literature and reference lists of retrieved articles. We included reports of quantitative studies published in all Persian and English articles from 2000 to 2021 that focused on Promethazine or Hyoscine during. Two authors independently screened titles and abstracts and assessed articles in full text against the inclusion criteria. These criteria included vertex presentation, no previous uterine surgery, intact membranes, and spontaneous labor, with mothers having no contraindications for normal vaginal delivery.   

 Out of a total of 170 records initially screened, we included 44 articles in our review, and other studies were excluded. The results showed that 10, 20, 40 mg of HBB decreased the first stage of labor duration by 147.02 min, 58.95 min, and 71.60 min, respectively. Additionally, HBB decreased the first stage of labor duration by 100.61 min in multiparous women and 66.04 min in primipara women. To evaluate the Promethazine effect on labor duration, the results showed that the combined MD was not significant (p=0.67, 0.85, and 0.44 in the first, second, and third stages, respectively).

 HBB is more effective in multiparous women compared to primiparous women. On the other hand, Promethazine has no effect on reducing total labor duration and any stages of labor, so its use is not recommended.