Carbetocin
Long-acting synthetic oxytocin analog used for postpartum hemorrhage prevention with extended duration of uterotonic action.
Chemical Identity
| Property | Value |
|---|---|
| Chemical Formula | C45H69N11O11S |
| Molecular Weight | 988.17 Da |
| CAS Number | 37025-55-1 |
| Peptide Class | Oxytocin Analog (Nonapeptide) |
| Route | IM, IV |
Structure
Carbetocin is a synthetic long-acting analog of oxytocin with a methyl ether group on the tyrosine residue at position 2 and 2-O-methyltyrosine substitution. These modifications increase resistance to oxytocinase degradation and extend the half-life from minutes to approximately 40 minutes.
Mechanism of Action
Carbetocin binds to oxytocin receptors on uterine myometrium, triggering sustained rhythmic contractions that compress uterine blood vessels. The extended half-life provides prolonged uterotonic effect compared to oxytocin, reducing the need for continuous infusion.
Clinical Applications
- Postpartum hemorrhage prevention: After cesarean section (WHO essential medicine)
- Active management of third stage of labor: Uterotonic prophylaxis
- Vaginal delivery: Alternative to oxytocin for PPH prevention
- Heat-stable formulation: WHO-approved for resource-limited settings
Pharmacokinetics
- Half-life: 40 minutes (vs 3-5 minutes for oxytocin)
- Onset: 2-5 minutes (IM)
- Duration: 1-2 hours (vs 30-60 minutes for oxytocin)
- Bioavailability: 80% (IM)
- Route: IM (single dose), IV
Safety and Side Effects
Abdominal pain, nausea, vomiting, headache, flushing, tremor, and pruritus. Less hypotension than oxytocin with IV use. Contraindicated before delivery and in patients with cardiovascular disease.
References
- Widmer, M., et al. (2018). Room temperature stable carbetocin for PPH prevention. Lancet, 392, 1359-1367.
- Attilakos, G., et al. (2010). Carbetocin versus oxytocin for cesarean section. BJOG, 117, 1453-1461.
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