Carbetocin Monotherapy Versus Carbetocin Plus Oxytocin Infusion in Elective Cesarean Delivery: A Non-Inferiority Trial

Summary

Background: Carbetocin is an established single-dose uterotonic agent for postpartum hemorrhage prophylaxis at elective cesarean delivery. Despite its proven efficacy, many clinicians routinely add a supplemental oxytocin infusion following carbetocin administration without evidence-based justification. Concurrent oxytocin receptor stimulation may be redundant, counterproductive through receptor desensitization, or incrementally beneficial - a mechanistic uncertainty that remains unresolved in the published literature.

Objectives: To determine whether carbetocin monotherapy (100 micrograms IV bolus plus placebo infusion) is non-inferior to carbetocin plus supplemental oxytocin infusion (10 IU over 4 hours) in preventing the need for additional uterotonic agents within 24 hours of elective cesarean delivery.

Study Design: Prospective, randomized, double-blind, placebo-controlled, non-inferiority trial with an integrated pilot phase. Phase 1 (Pilot, n=60) establishes local feasibility and event rate. Phase 2 (Full trial, n=332) provides the definitive non-inferiority analysis.

Participants: Women aged 18-45 years undergoing elective cesarean delivery under spinal anesthesia at Qassim University Medical City, singleton pregnancy at or beyond 37 weeks, ASA physical status II, preoperative hemoglobin 9 g/dL or more.

Interventions: Group C (Monotherapy): Carbetocin 100 micrograms IV bolus plus placebo saline infusion 500 mL over 4 hours. Group C+O (Combination): Carbetocin 100 micrograms IV bolus plus oxytocin 10 IU in 500 mL saline over 4 hours.

Primary Outcome: Proportion of patients requiring at least one additional uterotonic agent within 24 hours of delivery.

Secondary Outcomes: Quantitative intraoperative blood loss by gravimetric measurement; total 24-hour blood loss; actual blood loss by Gross formula; hemoglobin and hematocrit changes; uterine tone scores by verbal numerical rating scale (0-10) at 2, 5, and 10 minutes; incidence of postpartum hemorrhage; blood transfusion requirement; hemodynamic profiles; adverse effects.

Sample Size: 332 patients (166 per group), non-inferiority margin 10 percentage points, one-sided alpha 0.025, 80% power, estimated baseline event rate 10%, with 15% dropout allowance.

Conditions

• Postpartum Hemorrhage
• Uterine Atony
• Cesarean Section
• Blood Loss, Surgical

Interventions

DRUG

Carbetocin

Carbetocin 100 micrograms (1 mL) IV bolus administered over 1 minute immediately after umbilical cord clamping. Identical administration in both arms.

DRUG

Oxytocin

Oxytocin 10 IU added to 500 mL 0.9% sodium chloride, infused at 83 mL/hour over 4 hours, initiated within 2 minutes of carbetocin bolus. Administered in the combination arm only.

DRUG

Placebo Saline Infusion

500 mL 0.9% sodium chloride infused at 83 mL/hour over 4 hours, initiated within 2 minutes of carbetocin bolus. Visually identical to the active oxytocin infusion. Administered in the monotherapy arm only.

Sponsors & Collaborators

• Mansoura University

  lead OTHER

Principal Investigators

• Mohamed A Tolba, MD · Qassim University Medical City

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

45 Years

Sex

FEMALE

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-08-31

Primary Completion

2028-04-30

Completion

2028-08-31

Countries

• Saudi Arabia

Study Locations