Role of hyoscine N-butyl bromide (HBB, buscopan) as labor analgesic

Hyoscine N-butyl bromide (HBB) acts by inhibiting cholinergic transmission in the abdomino-pelvic parasympathetic ganglia, thus relieving spasm in the smooth muscles of gastrointestinal, biliary, urinary tract and female genital organs, especially the cervico-uterine plexus and aiding cervical dilatation.

The study was undertaken to observe the effects of 40 mg intravenous HBB as a labor analgesic and labor accelerant.

This prospective randomized control trial was carried out on 104 primigravidae with single live fetus in cephalic presentation, with spontaneous onset of labor, between 37-40 weeks of gestation.

Women were consecutively randomized into study (group I) and control (group II) groups, each with 52 patients after excluding high risk factors like preeclampsia, antepartum hemorrhage, previous uterine scar, and any contraindications to vaginal delivery. Group I received 40 mg HBB as a slow intravenous injection in the active phase of labor while Group II received 2 mL normal saline. Pain scores were assessed at baseline and two hours later. Secondary outcome measures compared were progress of labor based on injection delivery interval, mode of delivery and neonatal condition at birth.

Statistical significance was assessed by using Student's t-test and Chi-square test. P-value < 0.05 was taken as significant.

Pain relief of 35.6% was noted on visual analog score with the use of HBB. Mean duration of labor was 3 hours 46 minutes in Group I compared to 8 hours 16 minutes in Group II (P value: < 0.001). Mode of delivery and neonatal outcome were comparable. No adverse maternal effects were noted.

Intravenous Hyoscine N-Butyl Bromide causes pain relief of up to 36% and shortens the duration of active phase without any untoward short term fetal or maternal effects.