Nine residues running parturition, milk, and attachment. The disproportion between the size of the molecule and the size of the job is the whole field in miniature.
Identity
- Class
- Cyclic nonapeptide (9 aa)
- Source
- Hypothalamus (PVN/SON); released from the posterior pituitary
- Receptor
- Oxytocin receptor (OXTR), a class A GPCR
Key properties
Evidence floorClinicalREF1CLIN1Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.
Mechanism
Synthesized in the hypothalamus and released from the posterior pituitary, oxytocin drives uterine contraction in labor and milk ejection in lactation, and acts centrally in social and affiliative behavior. It differs from vasopressin by only two amino acids.
Reference notes
- Oxytocin and vasopressin differ by just two residues yet act on distinct receptor families.
- Its central (behavioral) and peripheral (reproductive) roles reflect receptor distribution, not different ligands.
- It is a textbook example of how small sequence differences encode large functional ones.
Regulatory status
United States · reviewed September 2026- Basis
- Synthetic oxytocin (Pitocin) approved for labour induction and postpartum haemorrhage.
Status describes the molecule as a drug substance under US law and is an editorial reading of the public record — approvals, trial registrations, and the FDA 503A bulk-substances list. It is not legal advice and it changes; the review date above is the last time the table was checked. Other jurisdictions are noted only where they differ materially.
Common questions
- What is Oxytocin?
- Parturition, lactation, and social bonding from a 9-residue peptide. Structurally it is Cyclic nonapeptide (9 aa).
- How does Oxytocin work?
- Synthesized in the hypothalamus and released from the posterior pituitary, oxytocin drives uterine contraction in labor and milk ejection in lactation, and acts centrally in social and affiliative behavior. It differs from vasopressin by only two amino acids.
- How strong is the evidence for Oxytocin?
- PeptideHormone grades Oxytocin at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an endogenous signal the body produces itself, and the tier is an editorial judgment about the public literature that can change as the science does.
- What is the half-life of Oxytocin?
- The reported circulating half-life of Oxytocin is ~1–6 min.
- Is Oxytocin FDA-approved?
- Yes — as of September 2026, Oxytocin is an approved prescription medicine in the United States. Synthetic oxytocin (Pitocin) approved for labour induction and postpartum haemorrhage. Status is US-centric and can change; check the FDA record for the current position.
In the literature
Live registry counts · retrieved- Ph 186
- Ph 2172
- Ph 363
- Ph 495
Searched as Oxytocin. Counts are search hits from the primary registries, not a curated set and not a grade – a measure of how much work exists on Oxytocin, not how it turned out.
Selected literature
Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.
- 1.The physiology and pharmacology of oxytocin in labor and in the peripartum period · American journal of obstetrics and gynecology, 2024 · PMID 38462255
- 2.Oxytocin, Neural Plasticity, and Social Behavior · Annual review of neuroscience, 2021 · PMID 33823654
External references
Oxytocin in the public knowledge graph — the same entity resolved across the authoritative chemistry and protein databases.