Treatment of Preterm Labor with the Oxytocin Antagonist Atosiban

Abstract

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 conducted at 4 sites. Successful tocolysis was defined as delay of delivery larger than 48 hours from starting atosiban and no need for an alternate tocolytic. Atosiban was administered by continuous intravenous infusion at a rate of 300 micrograms per minute until uterine contractions were absent 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 tocolysis was noted in 43 of 61 (70.5%). Four delivered spontaneously within 48 hours and 14 (23.0%) required an alternate tocolytic agent. The chance of successful tocolysis was related to the degree of cervical dilation at the start of therapy. Cessation of uterine contractions was noted in 38 patients (62.3%). A decrease in uterine contraction frequency of 50% or more was noted in 50 of 61 patients (82.0%). Four patients reported side effects (nausea, vomiting, headache, dysguesia, chest 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, its favorable side effect profile may give it a place in the armamentarium.

Effectiveness and safety of the oxytocin antagonist atosiban versus beta‐adrenergic agonists in the treatment of preterm labour

“…Earlier studies of atosiban in the treatment of preterm labour have shown that the inhibition of uterine contractility by intravenous administration was associated with a delay in delivery at least comparable to that of other tocolytic agents 20,21,24 . Goodwin et al…”

Direct Identification of Human Oxytocin Receptor-binding Domains Using a Photoactivatable Cyclic Peptide Antagonist

“…Because (i) 125 I-ZOTA displays an equivalent affinity for the human OTR and the human V 1a receptor, (ii) several residues involved in the binding of all classes of antagonists are conserved throughout the AVP/OT receptor family, and (iii) OTR and V 1a share a significant sequence identity in the upper part of TMD II, TMD III, TMD VI, and TMD VII as well as in the first extracellular loop, we propose that binding sites for 125 I-ZOTA in the OTR and V 1a receptor could be equivalent. However, to allow a more complete definition of the binding sites of the OTR for cyclic peptide antagonists such as 125 I-ZOTA or Atosiban (14,15) and to generate meaningful information on receptor/antagonist interactions, it will be necessary to perform other photolabeling studies.…”

“…The utility of such OT antagonists has been demonstrated clinically by using intravenously administered 1-deamino[DTyr(Et) 2 ,Thr 4 ,Orn 8 ]vasotocin (Atosiban). This peptide antagonist has been shown to inhibit uterine contractions in women with threatened and established preterm labor (14,15). However, the structure/function relationships of the functional domains of the OTR and the topography of the ligand-binding sites are still poorly investigated.…”

Different effects of tocolytic medication on blood pressure and blood pressure amplification

“…[35][36][37] For atosiban, no significant fall in DBP occurred, which is consistent with earlier work. [3,32,38,39] …”