Ritodrine and nifedipine as tocolytic agents: a preliminary comparison.

The effectiveness of the tocolytic agent and other betamimetic drugs in the treatment of preterm labor remains controversial. Effectiveness or efficancy of ritodrine has not yet convincingly been proven. A major concern are the marked side effects of beta-mimetics. The calcium channel blocker nifedipine has been used for tocolysis shortly after its introduction in clinical practice and is considered to be a probable good alternative for ritodrine. The efficacy of nifedipine versus ritodrine in the treatment of preterm labor was assessed in a retrospective study. 32 patients received intravenous ritodrine and 29 oral nifedipine. As endpoints were used: postponement of delivery, maternal side effects and perinatal outcome. The results of this retrospective study suggest that nifedipine is more successful in postponing delivery than ritodrine. Maternal side effects seemed to occur more frequently and be more serious in patients treated with ritodrine as compared to nifedipine. Perinatal outcome seemed better in the nifedipine group than in the ritodrine group. The promising data from small prospective studies and the results of this retrospective study warrant further large prospective studies on the definitive place of nifedipine in the treatment of premature labor. Until the results of such a trial are available we advocate the use of nifedipine in case of preterm labor, especially in a patient with diabetes mellitus, ruptured membranes, cardiac disease or multiple pregnancy, in order to avoid the characteristic side effects of beta-mimetics.