Calcium channel blockers for tocolysis: a review of their role and safety following reports of serious adverse events

Abstract

The use of nifedipine and other calcium channel blockers has become commonplace in the management of preterm labour. Several relatively small randomised trials have compared calcium channel blockers with beta-agonists and the meta-analyses of these studies have demonstrated superior or comparable efficacy and a superior adverse events profile. The safety of calcium channel blockers in pregnancy has not been rigorously evaluated and they remain unlicensed for use as tocolytics. Indeed, there is concern following a number of recent case studies that have reported serious adverse events after the administration of a calcium channel blocker as a tocolytic. In this article all these recently reported cases are critically reviewed and the pros and cons of tocolytic treatment options are discussed. Based on the findings of this review the following recommendations can be made with regard to tocolysis with calcium channel blockers: firstly, calcium channel blockers should not be combined with intravenous beta-agonists; secondly, intravenous nicardipine or high oral doses of nifedipine should not be used in cases where the mother is cardiovascular compromised or in cases of multiple gestation; finally, blood pressure should be monitored and cardiotocography recorded during the administration of immediate release tablets and patients should be advised to avoid chewing them. To truly establish the safety of tocolytics, all serious adverse effects of tocolytics should be reported to a central point and be critically reviewed.