title: Effect of an oxytocin receptor antagonist (atosiban) on uterine electrical activity.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effect of atosiban (Tractocile; Ferring, Limhamn, Sweden), an oxytocin receptor antagonist, on uterine electrical activity in women with preterm labor and to determine whether this information can assist in the prediction of preterm delivery.
  
  
  METHODS
  Uterine electrical activity was recorded prospectively in 21 women with preterm labor before and during treatment with Tractocile and, for purpose of comparison, in 4 pregnant women without uterine contractions to set the baseline of uterine electrical activity in a quiescent uterus. Uterine activity was recorded with a noninvasive, 9-channel recorder with an electromyography amplifier and a 3-dimensional position sensor with an automatic data analyzer. Uterine electrical activity was quantified by an electrical uterine monitor (EUM) and measured in microwatts per second (μW/s).
  
  
  RESULTS
  The overall pre-Tractocile EUM index was 3.43 ± 0.58 μW/s, which was significantly higher than baseline uterine activity in women without preterm contractions (2.3 ± 0.11 μW/s; P = .001). During the administration of Tractocile, the EUM index gradually decreased in a relatively constant rate from 3.43 ± 0.58 μW/s to 2.56 ± 0.88 μW/s after 330 minutes of continuous therapy (P < .001). The peak effect of Tractocile was observed 4 hours after the initiation of treatment and was followed by a relative plateau. Women with a latency of <7 days from treatment to delivery were characterized by a distinct EUM-pattern in response to Tractocile, compared with women with a latency of ≥7 days (P < .001). A similar EUM-pattern after the administration of Tractocile was also observed for women who delivered at <37 weeks of gestation compared with the women who delivered at term.
  
  
  CONCLUSIONS
  Tractocile reduces uterine electrical activity in women with preterm labor. This information can provide more insight into the effects of tocolytic agents and to aid in the risk stratification of preterm delivery in women with preterm contractions.
authors.affiliation: Helen Schneider Hospital for Women, Department of Obstetrics and Gynecology, Rabin Medical Center, Petach Tikva, and the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Hadar
authors.forename: Nir
authors.initials: N
authors.lastname: Melamed
authors.forename: Amir
authors.initials: A
authors.lastname: Aviram
authors.forename: Oded
authors.initials: O
authors.lastname: Raban
authors.forename: Liat
authors.initials: L
authors.lastname: Saltzer
authors.forename: Liran
authors.initials: L
authors.lastname: Hiersch
authors.forename: Yariv
authors.initials: Y
authors.lastname: Yogev
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000188:drug therapy*; D011247:Pregnancy; D047928:Premature Birth / Q000517:prevention & control*; D011446:Prospective Studies; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors*; D015149:Tocolytic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016896:Treatment Outcome; D014599:Uterus / Q000187:drug effects* / Q000502:physiology; D014668:Vasotocin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D018045:Receptors, Oxytocin; D015149:Tocolytic Agents; C047046:atosiban; D014668:Vasotocin
keywords: EMG; Tractocile; electrical uterine activity; preterm birth