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Oxytocin (Nonapeptide Hormone) Research Reference

PubChem CID: 439302 | CAS: 50-56-6 | Molecular Formula: C₄₃H₆₆N₁₂O₁₂S₂ | Molecular Weight: 1007.19 g/mol

Sequence: Cys–Tyr–Ile–Gln–Asn–Cys–Pro–Leu–Gly–NH₂ | Class: OXTR Agonist | FDA-Approved Obstetric Hormone | Synthetic Nonapeptide | Hypothalamic Neuropeptide | Social Cognition Neuromodulator

Regulatory Status – Read Before Proceeding

Oxytocin (PubChem CID 439302; CAS 50-56-6) is an FDA-approved prescription drug in the United States for a narrow set of obstetric indications under the brand name Pitocin and generic equivalents. It is legally available only with a prescription and must be administered under qualified medical supervision in an appropriately equipped clinical setting.

Critical regulatory distinction: While intravenous and intramuscular oxytocin formulations are FDA-approved, compounded oxytocin products — including intranasal sprays, subcutaneous preparations, and any non-commercially-equivalent formulation marketed for psychiatric, social-cognitive, or consumer wellness applications — are classified as unapproved new drugs under Sections 505(a) and 301(d) of the Federal Food, Drug, and Cosmetic Act. The 2025–2026 FDA enforcement wave covering the U.S. peptide and compounding market specifically targeted vendors marketing hormones and peptides via RUO or wellness framings for unapproved indications.

Intranasal oxytocin has no FDA-approved indication as of June 2026 for any neuropsychiatric, behavioral, social-cognitive, or consumer application. Investigational use remains within registered clinical trials only. This document is a scientific reference resource for academic investigators, pharmaceutical researchers, regulatory affairs specialists, and compliant content creators. It is not a product listing, not a dosing guide, not a clinical protocol, and does not constitute any recommendation for human use.

Product overview

Oxytocin (PubChem CID 439302; CAS 50-56-6) is a cyclic nonapeptide hormone and neuropeptide synthesized in magnocellular and parvocellular neurons of the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus, stored in the posterior pituitary, and released both peripherally into the bloodstream and centrally into limbic and cortical brain regions. Its canonical amino acid sequence is Cys–Tyr–Ile–Gln–Asn–Cys–Pro–Leu–Gly–NH₂, stabilized by an intramolecular disulfide bridge between the N-terminal and sixth-position cysteine residues, creating a 6-amino-acid ring with a tripeptide C-terminal amide tail.

In the United States, oxytocin occupies a well-defined but dual regulatory position. As a commercially manufactured injectable drug (Pitocin; generic oxytocin injection), it is fully FDA-approved for induction and augmentation of labor, management of postpartum hemorrhage, and adjunctive management of incomplete abortion. Outside these approved obstetric indications, including intranasal preparations for neuropsychiatric or social applications, oxytocin is investigational. Compounded oxytocin products not meeting 503A or 503B exemptions are classified as unapproved new drugs under current FDA enforcement posture, which intensified significantly throughout 2025 and into 2026.

For 2026 U.S. research, health education, and peptide science content, oxytocin represents a high-stakes YMYL subject at the intersection of reproductive medicine, neuroscience, and social cognition research — three domains that Google’s Helpful Content algorithm treats with maximum scrutiny under the E-E-A-T framework. This document provides a precise, compliance-graded scientific reference for investigators, regulatory professionals, and content developers navigating the 2026 U.S. landscape.

Chemical Identity – Registry and Structural Reference

PubChem Compound Record – CID 439302

Oxytocin is registered as a single, structurally defined compound in the PubChem database (CID 439302), reflecting its synthetic nature as a single-sequence peptide. This is a critical distinction from heterogeneous polypeptide extracts such as Thymalin. The PubChem record provides authoritative chemical identity: molecular formula, InChI, SMILES, and 2D/3D structural diagrams suitable for educational and reference use.

Oxytocin 2D Structure | Generated via RDKit from verified PubChem SMILES (CID 439302) | Cys–Tyr–Ile–Gln–Asn–Cys–Pro–Leu–Gly–NH₂ | C₄₃H₆₆N₁₂O₁₂S₂ | MW 1007.19 g/mol | CAS 50-56-6

Receptor Pharmacology – OXTR and Structural Selectivity

The oxytocin receptor (OXTR) is a class A G-protein-coupled receptor (GPCR) primarily coupled to Gq/11 proteins. Activation by oxytocin initiates the PLC-IP3-DAG signaling cascade, releasing intracellular calcium from the endoplasmic reticulum and activating protein kinase C (PKC). In uterine myometrium and mammary gland myoepithelium, this calcium mobilization drives rhythmic smooth muscle contraction critical to parturition and milk ejection. In the central nervous system, OXTR is expressed in the amygdala, hippocampus, nucleus accumbens, bed nucleus of the stria terminalis, and prefrontal cortex, where oxytocin modulates social cognition, affective processing, and stress response regulation.

Oxytocin and arginine vasopressin (AVP/ADH) share a near-identical nonapeptide scaffold, differing only at positions 3 (Ile vs Phe) and 8 (Leu vs Arg). This structural similarity results in partial receptor promiscuity: at pharmacological concentrations, oxytocin can activate vasopressin V1a receptors and V2 receptors, while AVP can activate OXTR. This cross-reactivity has significant pharmacological implications — particularly explaining water intoxication risk at high obstetric oxytocin doses and complicating interpretation of intranasal behavioral research outcomes.

Mechanism of Action and Systems Pharmacology

Safety Profile – Approved and Investigational Contexts

Important safety context: For approved obstetric indications, oxytocin carries a well-characterized, serious adverse-effect profile requiring continuous fetal and maternal monitoring in equipped facilities. For intranasal investigational uses, no validated safety profile from FDA-registered human clinical trials exists for any indication beyond obstetrics. This section covers both contexts.

Research History – From du Vigneaud to 2026

U.S. Peptide Market Context and Compliance Environment

Oxytocin occupies a structurally different position in the 2026 U.S. peptide and health-science market compared to most research peptides. Unlike BPC-157, TB-500, or thymic bioregulators that exist exclusively in a research/investigational gray zone, oxytocin is a dual-natured compound: an FDA-approved drug for obstetric indications and simultaneously an investigational agent for a wide array of neuropsychiatric and social-cognitive applications. This duality creates layered compliance challenges for content creators, vendors, and health educators.

The 2025–2026 FDA enforcement wave that generated 50+ warning letters against peptide vendors, compounders, and health marketing operations specifically caught vendors positioning hormones — including oxytocin — in consumer-wellness framings. Compounded intranasal oxytocin “bonding sprays” and “trust hormone” nasal spray products, while not the primary targets of the initial 2024 wave, fall squarely within the enforcement architecture defined by Warning Letter 669074 (Thymalin/US Chem Labs) and the March 2026 Gram Peptides and Prime Sciences letters: the totality of commercial conduct determines drug intent, not the disclaimer on a label.

For compliant U.S. operations in 2026, the only defensible commercial framework for oxytocin involves: (1) supplying FDA-approved formulations only through licensed pharmaceutical channels with valid prescriptions; (2) providing research-standard oxytocin as a reference compound to academic and pharmaceutical institutions with strict RUO documentation and no human-use implication; or (3) conducting registered clinical trials under an IND for investigational applications. Consumer-facing “oxytocin supplement” or “intranasal spray kit” positioning is incompatible with current FDA enforcement posture and exposes businesses to FDA action, FTC enforcement, and Google YMYL algorithmic penalties simultaneously.

From a Google 2026 content standpoint, oxytocin sits at the intersection of three high-YMYL categories: reproductive health, mental health, and hormone/drug therapy. The March 2026 and May 2026 Core Updates further elevated the E-E-A-T threshold for medical and pharmacological content. Pages that demonstrate original research synthesis, verifiable citations to primary literature and FDA sources, clear regulatory disclosure, and risk-aware framing consistently outperform thin or promotional health content in competitive keyword spaces.

Frequently Asked Questions – Scientific and Regulatory Reference

Q1: What is oxytocin and what is its PubChem CID?

Oxytocin is a cyclic nonapeptide hormone and neuropeptide (PubChem CID 439302; CAS 50-56-6; C43H66N12O12S2; MW 1007.19 g/mol) synthesized in the hypothalamic paraventricular and supraoptic nuclei. Its amino acid sequence is Cys–Tyr–Ile–Gln–Asn–Cys–Pro–Leu–Gly–NH2, stabilized by an intramolecular disulfide bridge. Unlike heterogeneous polypeptide extracts, oxytocin is a single-molecule compound with a precise structural identity registered in PubChem under CID 439302. The associated substance record SID 134971638 maps USP, INN, BAN, and JAN nonproprietary names to this compound, confirming pharmacopoeial alignment across international naming systems.

Q2: Is oxytocin FDA-approved, and for what indications?

Yes — but for narrow, tightly specified obstetric indications only. FDA-approved uses include: (1) induction of labor at term or near-term when medically indicated, such as preeclampsia, maternal diabetes, premature rupture of membranes, or uterine inertia; (2) augmentation of dysfunctional labor; (3) management of postpartum hemorrhage via parenteral uterotonic administration; and (4) adjunctive management of incomplete or inevitable abortion. Intranasal oxytocin is not FDA-approved for any psychiatric, behavioral, social-cognitive, or consumer wellness indication as of June 2026. Any content suggesting otherwise, or marketing compounded sprays for unapproved uses, constitutes potential misbranding under FDA’s current enforcement posture.

Q3: What does the evidence show for intranasal oxytocin in autism spectrum disorder (ASD)?

The evidence is mixed and, on balance, does not support intranasal oxytocin as an established or generally effective intervention for ASD. The NIH ECHO trial — the largest and most rigorous RCT to date (Sikich et al. 2021 NEJM; PMID 34587383; n=290, ages 3–17, 24 weeks of treatment) — found no statistically significant improvement in social functioning compared to placebo. While some smaller prior trials showed modest social-function improvements, the 2024 meta-analysis of 12 RCTs found limited overall evidence, with possible modest benefit at high doses and possible sex-differential responses. Intranasal oxytocin remains strictly investigational for ASD and should be discussed in educational content as an active research area with an inconclusive evidence base.

Q4: Can intranasal or compounded oxytocin be legally sold in the U.S. in 2026?

Not for human or consumer use in any form without a valid prescription, FDA approval, or registered IND. Compounded oxytocin preparations that are essentially copies of the FDA-approved product (Pitocin) are restricted under 503A unless specific patient-specific justification exists, such as documented excipient allergy. Compounded intranasal sprays, which are not therapeutically equivalent to approved IV/IM formulations, fall outside any approved compounding pathway and are classified as unapproved new drugs under the 2025–2026 FDA enforcement framework. Vendors supplying oxytocin nasal sprays, reconstitution kits, or dosing guides for human use face the enforcement template established across 50+ FDA warning letters issued in 2024–2026.

Q5: How does oxytocin differ from vasopressin at the receptor level?

Oxytocin and arginine vasopressin (AVP) differ by only two amino acids at positions 3 and 8, but these differences drive substantially different receptor selectivity profiles. Oxytocin preferentially binds OXTR (Gq/11-coupled), while AVP preferentially activates V1a (Gq/11), V1b (Gq/11), and V2 (Gs-coupled, antidiuretic) receptors. However, at pharmacological concentrations, oxytocin activates V1a receptors, contributing to vasoconstriction and antidiuretic effects observed with high-dose obstetric infusions. Conversely, AVP can activate OXTR, potentially influencing social behavior in vasopressin research models. This pharmacological cross-reactivity is critically important when interpreting neuropsychiatric clinical trial results.

Q6: What are the serious safety risks of oxytocin in obstetric practice?

Oxytocin has a narrow therapeutic window in obstetrics. Primary serious risks include: uterine tachysystole, uterine hypertonus, uterine rupture, fetal hypoxia and acidosis, non-reassuring fetal heart rate patterns, and emergency C-section. Maternal risks include hypotension with rapid IV bolus, water intoxication and dilutional hyponatremia at high infusion rates, cardiac arrhythmias, and — in severe overdose — seizures and maternal death. Contraindications include significant cephalopelvic disproportion, placenta previa, vasa previa, cord presentation, and uterine hypertonicity. The FDA Pitocin label requires continuous fetal and uterine monitoring and immediate surgical delivery capability at the point of administration.

Q7: What is appropriate 2026 content framing for oxytocin on a U.S. health or peptide research site?

For Google 2026 E-E-A-T/YMYL compliance and FDA/FTC regulatory safety, oxytocin content must: (1) clearly identify oxytocin as an FDA-approved prescription drug for obstetric indications, not an OTC supplement or research peptide; (2) rigorously separate approved obstetric applications from investigational intranasal/psychiatric research, using explicit language such as “investigational,” “not FDA-approved for this indication,” and “clinical trial”; (3) accurately represent the mixed and mostly inconclusive evidence from intranasal ASD and psychiatric trials; (4) avoid all consumer-use language, dosing guidance, sourcing references, or “bonding/trust/love hormone” framing; and (5) use PubChem CID 439302 identity data with proper educational captions, not as product branding. High-quality oxytocin content is anchored in primary literature, FDA prescribing information, and peer-reviewed reviews, not anecdotal wellness claims.

Q8: What is oxytocin’s relationship to social behavior and why is “love hormone” framing problematic?

Oxytocin does modulate social cognition circuits via CNS OXTR in the amygdala, nucleus accumbens, and prefrontal cortex — reducing threat-response reactivity, increasing attention to social stimuli, and facilitating prosocial approach behavior in experimental paradigms. However, the “love hormone” or “trust molecule” popular framing oversimplifies a complex neuromodulatory system and creates clinical and regulatory problems. Oxytocin’s behavioral effects are highly context-dependent, bidirectional, and modulated by individual baseline biology, social context, and receptor polymorphisms. Content that positions oxytocin as a reliable prosocial enhancer or consumer “bonding supplement” is both scientifically inaccurate and a significant FDA/FTC enforcement risk in 2026, as it implies therapeutic benefit for an unapproved application.

Regulatory and Compliance Statement – Scientific Reference Document

Key References – PubMed / PubChem / FDA / Google – Verified

Profound Aminos © 2026 | Scientific Reference Document | Educational and Professional Use Only

profoundaminos.com | Google 2026 GSC-Safe Content | All Trigger Words Audited | E-E-A-T Compliant | YMYL Framework | PubChem-Anchored

Oxytocin (PubChem CID 439302) is FDA-approved for obstetric indications only. Intranasal and compounded formulations are not approved for any indication as of June 2026. This document is not a product listing. No consumer or self-directed use is implied or recommended.

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