Cardiac effects of oxytocin 2.5 U or carbetocin 100 µg after caesarean
delivery: study protocol for a prospective randomized controlled
Objective: Oxytocin may cause dose-dependent ischaemic echocardiogram
changes, prolongation of QT time and release of myocardial biomarkers.
We have previously demonstrated comparable vasodilatory effects of
oxytocin and carbetocin and are now undertaking a Phase 4 trial to
investigate whether carbetocin causes changes to myocardial markers.
Design: Randomized controlled trial. Setting: Obstetrics units at Oslo
University Hospital or and Akershus University Hospital, Norway.
Population or sample: Planned enrolment of 240 healthy, singleton
pregnant women aged 18 to 50 years, who are undergoing planned caesarean
delivery Methods: Based on pilot study data, each participant will
receive a 1 -minute intravenous injection of either oxytocin 2.5 U or
carbetocin 100 µg during caesarean section. Main outcome measures: The
primary outcome is prespecified as the change from baseline in
high-sensitive troponin I plasma concentrations at 6–10 hours after
study drug administration. Secondary outcomes include uterine tone grade
at 2.5 and 5 minutes after study drug administration, adverse events for
up to 48 hours after study drug administration, estimated blood loss
within 8 hours of delivery, need for rescue treatment and
direct/indirect costs. Results: Enrolment and primary analysis is
expected to be completed by the end of 2021. Conclusions: Any potential
cardiotoxicity difference between oxytocin and carbetocin will help
inform treatment decisions for pregnant women.