Meperidine versus valethamate bromide in shortening the duration of labor

Painless and short labor without causing any adverse effects on the mother and fetus is desired by every pregnant women and a constant aim of active management for obstetricians. The progress of labor is assessed by progressive dilatation of cervix and progressive descent of the presenting part. Protraction of the first stage of labor, one of the components of prolonged labor, is multifactorial, and cervical dilatation is one of the important factors which determines the duration of the first stage of labor and is the end result of all driving forces of uterine contraction against passive tissue resistance. Failure of progressive dilatation of cervix in labor can cause prolonged labor. In addition to mechanical methods such as cervical membrane sweeping, cervical stretching, and amniotomy, there are various pharmacological methods to facilitate cervical dilatation. The role of oxytocin has been established worldwide in the inducing and augmentation of labor, and prostaglandins have been used in various formulations for induction of labor. Cervical application of hyaluronidase, estradiol and relaxin has also been used with some success. Various drugs such as phloroglucinol, tranquilizers, especially diazepam, opioids, especially meperidine, and antispasmodics such as valethamate bromide, drotaverine hydrochloride and hyosin-N-butyl bromide have been used for shortening the duration of labor. Meperidine has been widely used for relief of labor pain and dystocia during the first stage of labor since its introduction in the late 1940s. Whereas analgesia is maximal about 30 to 45 minutes after an intramuscular (IM) injection, it develops almost immediately following intravenous administration. Meperidine readily crosses the placenta, and the half life is approximately 13 hours or longer in the newborn. Its depressant effect in the fetus follows closely behind the peak maternal analgesic effect. In the first randomized controlled trial to evaluate the use of meperidine as a way to shorten the duration of labor, meperidine was found the absent of any benefit on labor duration and presence of maternal adverse effects as well as other deleterious effects in the newborn. Valethamate bromide is both a central and a peripheral antimuscarinic agent, which is a competitive inhibitor of acetylcholine at the muscarinic receptors. After IM administration, onset of action occurs in about 20–30 minutes. Plasma half-life is 4 hours. It crosses the placenta and is secreted in the breast milk. It is completely metabolized in the liver and is excreted in the urine as both unchanged drug and metabolites. Neurotropic and musculotropic actions of valethamate bromide result in relaxation of cervical musculature leading to quick dilatation of the cervix and shortened labor. The objective of this study was to compare the efficacy, safety and side effects of meperidine, valethamate bromide and placebo in shortening the duration of labor.