Atosiban (RW22164; RWJ22164) is indeed a nonapeptide and a competitive antagonist of the vasopressin and oxytocin receptors. It is structurally similar to oxytocin but lacks the amino group at the N-terminus, making it a desamino-oxytocin analogue. Atosiban is primarily used as a tocolytic agent, which means it helps to inhibit premature labor by blocking the action of oxytocin on the uterus. This makes it particularly valuable in the management of spontaneous preterm labor, as it can help delay delivery, providing critical time for administering corticosteroids to enhance fetal lung maturity or for transferring the mother to a facility with appropriate neonatal care.
