TREATMENT OF PRETERM LABOR WITH THE OXYTOCIN ANTAGONIST ATOSIBAN

The purpose of this study was to describe the course of preterm labor in patients receiving a standard intravenous infusion of the oxytocin antagonist atosiban. An open-labeled, non-randomized study was conduct ed at 4 sites. Successful tocolysis was defined as delay of delivery l arger than 48 hours from starting atosiban and no need for an alternat e tocolytic. Atosiban was administered by continuous intravenous infus ion at a rate of 300 mu g per minute until uterine contractions were a bsent for 6 hours, or up to a maximum infusion time of 12 hours. Sixty -two patients of between 20 and 36 weeks' gestation were enrolled over 6 months. One had rupture of membranes and was excluded. Successful t ocolysis was noted in 43 of 61 (70.5%). Four delivered spontaneously w ithin 48 hours and 14 (23.0%) required an alternate tocolytic agent. T he chance of successful tocolysis was related to the degree of cervica l dilation at the start of therapy. Cessation of uterine contractions was noted in 38 patients (62.3%). A decrease in uterine contraction fr equency of 50% or more was noted in 50 of 61 patients (82.0%). Four pa tients reported side effects (nausea, vomiting, headache, dysguesia, c hest pain), but in no case did side effects require discontinuation of the medication. Intravenous administration of atosiban is associated with a delay in delivery comparable to that seen with other tocolytics . If this effect is confirmed in planned placebo-controlled trials, it s favorable side effect profile may give it a place in the armamentari um.