Carbetocin is a synthetic, long-acting version of oxytocin. It was built by modifying the natural hormone so the molecule resists the enzymes that break oxytocin down quickly, which gives it a half-life of roughly 40 minutes instead of a few. Doctors use it for one job: stopping the uterus from bleeding too much after a baby is delivered. It goes by the brand names Pabal and Duratocin (also Lonactene and Duratobal in some markets), and it first reached the market in Canada in 1997.
The full chemical name in the synonym lists, deamino-1-monocarba-2-O-methyltyrosine-oxytocin, describes exactly what was changed from the parent hormone. CAS registry number 37025-55-1.
What it does in the body
Carbetocin binds to oxytocin receptors on the smooth muscle of the uterus. That triggers rhythmic contractions, raises the frequency of contractions already happening, and increases uterine tone. A firmly contracted uterus clamps down on the blood vessels that fed the placenta, which is how the drug reduces bleeding. The UK product information for Pabal describes it as "a long-acting oxytocin agonist" that "selectively binds to oxytocin receptors in uterine smooth muscle." A single 100-microgram dose, given by injection, starts working within about two minutes and keeps the uterus contracting for roughly an hour (Pabal SmPC, electronic Medicines Compendium).
That single-shot profile is the practical selling point. Oxytocin often has to be run as an infusion; carbetocin is one intravenous or intramuscular injection.
What it is approved for
The approved indication is narrow and specific. Per the SmPC, "PABAL is indicated for the prevention of postpartum haemorrhage due to uterine atony." It was originally cleared for use after caesarean section and has since been approved in dozens of countries for use after vaginal delivery as well. This is a hospital drug given by clinicians at the moment of birth. It is not a consumer product, and nothing here is medical or dosing advice.
The evidence base
Carbetocin is unusually well studied for a peptide of this kind. The headline trial is CHAMPION, a WHO-led, double-blind, non-inferiority study that randomised 29,645 women across 23 hospitals in 10 countries to receive either intramuscular heat-stable carbetocin (100 micrograms) or oxytocin (10 IU) right after vaginal birth. The result: heat-stable carbetocin was clinically non-inferior to oxytocin for the outcome of blood loss of at least 500 mL or use of additional uterotonics. Non-inferiority was not demonstrated for the stricter outcome of blood loss of 1,000 mL or more (Widmer et al., *NEJM* 2018).
Why the heat-stable formulation matters: ordinary oxytocin degrades when warm and needs continuous refrigeration. A version of carbetocin that stays stable at up to 30°C for years removes the cold-chain problem, which is a real obstacle in many low-resource settings. On the strength of CHAMPION, WHO updated its 2018 recommendations on uterotonics for postpartum haemorrhage prevention to include carbetocin. Smaller trials and meta-analyses comparing carbetocin with oxytocin in caesarean and vaginal delivery have generally found it at least as effective, with a similar side-effect profile (headache, flushing, nausea, tremor) (Cochrane/CADTH review summary, NCBI Bookshelf).
A second, separate research story
Because oxytocin signalling is tied to appetite and social behaviour, carbetocin was tested far outside obstetrics, as an intranasal treatment for hyperphagia in Prader-Willi syndrome. An early phase 3 study (CARE-PWS) reported improvements in hyperphagia and anxiety scores in one dose arm (Roof et al., *J Clin Endocrinol Metab* 2023). The larger, confirmatory phase 3 COMPASS PWS trial run by Acadia Pharmaceuticals, with 175 participants, then failed: in September 2025 Acadia announced the drug did not beat placebo on the primary hyperphagia endpoint or on any secondary endpoint. So the intranasal-for-PWS program does not have the evidence its developers hoped for, which is worth knowing if you see carbetocin discussed in that context.
Purity, sourcing and what to check
As an injectable obstetric medicine, pharmaceutical carbetocin is a regulated prescription product made to manufacturing standards and administered in clinical settings. Material sold through research-chemical channels is a different thing entirely. It is not a quality-controlled drug, it carries no clinical guarantees, and it should be treated as research-use-only, not for human consumption. If you are evaluating any vendor-supplied peptide, the documents that matter are a recent certificate of analysis (COA) tied to the specific lot, with identity confirmed by mass spectrometry and purity by HPLC. peptideone aggregates independent third-party rater signals where they exist, but for a compound like carbetocin those signals are thin, and an unverified COA is not a substitute for a regulated medicine.