Background/purpose: Management of preterm labor involves the use of tocolytic drugs to inhibit preterm uterine contractions. This study compared the efficacy and safety of intravenous administration of atosiban and ritodrine in the treatment of spontaneous preterm labor.
Methods: A randomized study was conducted in pregnant women of Chinese origin in Taiwan with threatened preterm delivery. Patients were randomized to receive either atosiban (n = 23) or ritodrine (n = 22). Tocolytic efficacy of the drug was assessed as the proportion of women who did not deliver and did not need alternative tocolytic treatment at 7 days after therapy initiation. Safety of the drugs was assessed as the number of adverse events or neonatal morbidity.
Results: The number of women who did not deliver and did not require alternative tocolytic therapy at 7 days was similar between the atosiban and ritodrine groups. There were no serious adverse events, but maternal cardiovascular adverse events, particularly tachycardia, occurred significantly more in women treated with ritodrine (0% atosiban vs. 18.18% ritodrine, p < 0.05). There was no difference in neonatal or infant outcome between the two drugs.
Conclusion: The present study showed similar effectiveness between atosiban and ritodrine, while tachycardia occurred more frequently in women treated with ritodrine. These results indicate that atosiban is an effective tocolytic drug without the conventional cardiovascular side effects often seen with beta-agonist treatment.