Calcium channel blockers for the management of preterm birth: a review.

Preterm birth continues to be the leading cause of perinatal morbidity and mortality. A wide range of tocolytics have been utilized for the management of preterm labor. Calcium channel blockers, namely nifedipine, gained popularity as tocolytics due to the oral route of administration, availability of immediate- and slow-release preparations, the low incidence of maternal adverse effects associated with their use, and the fact that they are inexpensive. This article reviews the available literature on the clinical utility of calcium channel blockers for acute and maintenance tocolysis with special emphasis on potential adverse effects, the most appropriate dose/regimen, and contemporary practice patterns among obstetricians. There are no randomized, placebo-controlled studies demonstrating the benefit of nifedipine in preterm labor. A suggested tocolytic protocol would be to start with the lowest dose of oral immediate-release nifedipine. For the first 48 hours thereafter, all attempts should be made not to exceed 60-mg daily doses.