Treatment of preterm labor with the oxytocin antagonist atosiban: a double-blind, randomized, controlled comparison with salbutamol

Objective: To compare the efficacy and safety of atosiban and salbutamol in the treatment of preterm labor. Studs, design: A multicenter, double-blind , double-placebo, randomized, controlled trial. Women (n = 241) diagnosed w ith preterm labor at 23-33 gestational weeks were enrolled and received eit her atosiban (n = 119) or salbutamol (n = 122). At randomization, women wer e stratified by gestational age (less than or equal to 28 weeks and > 28 we eks). Atosiban (i.v. bolus dose of 6.75 mg, then 300 mug/min for 3 h and 10 0 mug/rain for up to 48 h) and salbutamol (2.5-45 mug/min) were administere d by i.v. infusion for up to 48 h. Retreatment with study drug or an altern ative tocolytic agent was allowed. Main outcome measures included tocolytic effectiveness which was assessed in terms of the number of women undeliver ed after 48 h and 7 days. Tocolytic efficacy and tolerability were assessed in terms of the proportion of women undelivered and who did not require al ternative tocolytic therapy at 48 h and 7 days of starting treatment. Safet y was assessed in terms of maternal side effects and neonatal morbidity. Re sults: Tocolytic effectiveness at 48 It was 93.3 versus 95.0% (P = 0.67) an d after 7 days was 89.9 versus 90.1% (P = 0.93) in the atosiban and salbuta mol groups, respectively, Tocolytic efficacy and tolerability within 48 h w as 79.8 versus 75.2% (P = 0.15), and after 7 days was 58.8 versus 46.3% (P = 0.021) in the atosiban and salbutamol groups, respectively. Maternal adve rse events, including serious events, occurred more frequently in the salbu tamol group. Neonatal outcomes were comparable between the study groups. Co nclusions: The oxytocin antagonist atosiban was found to be better tolerate d by both mother and fetus than salbutamol, with a comparable neonatal and infant safety profile, and atosiban was as effective as salbutamol in delay ing threatened preterm birth. This study supports the clinical use of atosi ban in the treatment of preterm labor. (C) 2001 Elsevier Science Ireland Lt d. All rights reserved.