[Efficiency and tolerance of calcium channel blockers as first-line tocolysis]

Calcium channel blockers are widely used as first-line tocolytic, but prescribed off-label for this indication. The primary objective of this review is to evaluate the efficiency and safety of calcium channel blockers compared to placebo and to all tocolytic agents used. This review concerns the randomized trials, comparative studies and meta-analyzes of randomized trials on the subject. Nifedipine is superior to placebo in reducing the risk of delivery within 48 hours (RR=0.3; 95 % CI [0.21-0.43]), but induces more maternal side effects (RR=3.8; 95 % CI [1.02-16.92]). The effectiveness of nifedipine is greater than that of betamimetics to prolong pregnancy beyond 48 hours (OR=1.52; 95 % CI [1.03-2.24]), and up to 34 weeks (OR=1.87; 95 % CI [1.11-3.15]), with a lower incidence of adverse events requiring discontinuation of treatment in case of use of nifedipine (RR=0.22; 95 % CI [0.10-0.48]), but no significant difference in neonatal mortality. Efficacy of nifedipine is similar to that of oxytocin antagonists to prolong pregnancy beyond 48 hours (RR=0.92; 95 % CI [0.37-2.30]), but causes more mild maternal adverse events (RR=2.61, 95 % CI [1.43-4.74]). Nicardipine is not evaluated as nifedipine as a tocolytic treatment. It appears as effective as salbutamol and appears to have fewer maternal side effects than IV salbutamol.