OBJECTIVE

Although valethamate bromide is used liberally to facilitate cervical dilatation, there is little and inconclusive data about its efficacy. The aim of this study was to determine the effect of valethamate bromide on the duration of labor.

Patient(s) and Method(s)

A total of 98 women with term pregnancies admitting to our clinic for vaginal delivery were included in this study. Patients were randomized to receive intramuscularly either 8mg/mL valethamate bromide (n=48) or a similar amount of placebo (1 mL 0.9% NaCl; n=50) at the beginning of the active phase (i.e. cervical dilatation 4-5cm) of labor. The medications were given at hourly intervals for a total of three doses. Primary outcome measures were (1) time elapsed until the second stage of labor, (2) duration of the second stage of labor and (3) need for augmentation of labor with oxytocine. Secondary outcome measure was the subjective impression of the physician about the efficacy of the medication and associated adverse effects.

Result(s)

Maternal age (25.6 ± 5.7 vs. 26.4 ± 6.3 years), gestational age at delivery (39.0 ± 1.5 vs. 38.9 ± 1.8 weeks), birth weight (3285 ± 334 vs. 3252 ± 460g) and parity (27/48 vs 28/50 primipara) of both groups were comparable (p>0.05). The active phase of labor was significantly shorter in the Valethamate bromide group than in the placebo group (200.2 ± 88.3 vs. 267.2 ± 131.3 minutes; p=0.04). Valethamate bromide shortened the active phase of labor in primiparas (210.3 ± 93.5 vs. 287.1 ± 130.3 minutes; p=0.015) but not in multiparas (187.1 ± 81.4 vs. 241.9 ± 131.1 minutes; p=0.11). The duration of the second stage of labor was comparable between both groups (39.1 ± 50.9 vs. 58.0 ± 120.9 minutes; p>0.05). The need for oxytocine was similar in both goups (9/48 vs. 6/50; p>0.05). The number of physicians who found that the medication was effective was significantly higher in the valethamate bromide group (39/48) than in the placebo group (28/50) (p=.001).

Conclusion(s)

Valethamate bromide administered during the active phase of labor significantly shortens the duration of the first stage of labor when compared with placebo.

Keywords: valethamate bromide, labor, delivery, cervical dilatation, duration, spasmolytic