Carbetocin Acetate | CAS 37025-55-1 | Oxytocin Receptor Agonist (Research Use Only) | Knowlux

Product Description

Carbetocin Acetate, CAS 37025-55-1, is a synthetic cyclic octapeptide analogue of oxytocin, supplied by Knowlux for laboratory research use. The sequence is Butyryl-MeOTyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2, with a thioether linkage between the butyryl group and the cysteine residue. The molecular formula is C45H69N11O12S and the molecular weight is 988.16 g/mol (free peptide basis). Each lot is released with a lot-specific COA, MSDS and analytical traceability.

CAS and Salt Form Clarification: CAS 37025-55-1 is the registry associated with Carbetocin, and it is applied in commercial listings to both the free peptide and the acetate salt. Sigma-Aldrich and Krackeler explicitly annotate the CAS as free base and present the empirical formula as C45H69N11O12S.xC2H4O2, indicating that the acetate salt is a derivative of the free peptide rather than a separately registered entity. The molecular weight of the free peptide is 988.16. The acetate salt molecular weight depends on the acetate stoichiometry: a monoacetate would be approximately 1048.21 (988.16 + 60.05), and this value appears in some supplier listings under formula C47H73N11O14S. Listings showing molecular weights near 988.16 without an acetate component refer to the free peptide basis. Knowlux declares the salt stoichiometry, acetate content, and water content per lot on the COA. Buyers should confirm whether the quoted material is reported on a free-peptide or acetate-salt basis before procurement.

Structural Note: Carbetocin is distinguished from oxytocin by two key modifications: a butyryl group at the N-terminus and an O-methyl tyrosine at position 2. The thioether linkage between the butyryl-4-yl group and the cysteine residue replaces the disulfide bridge found in native oxytocin, a structural feature that contributes to the analogue's enhanced metabolic stability. The C-terminus is glycinamide (Gly-NH2), amidated against carboxypeptidase degradation.

Product Parameters

Product Details

1. Overview

Carbetocin is a synthetic octapeptide analogue of oxytocin developed for its prolonged uterotonic activity relative to the native hormone. It acts as an agonist at the oxytocin receptor (OXTR), a Gq/11-coupled GPCR that triggers intracellular calcium mobilization and smooth muscle contraction. KEGG classifies Carbetocin within the oxytocin and analogues drug group (ATC code H01BB03) and annotates its target as OXTR. In clinical medicine, Carbetocin Acetate is used for the prevention of uterine atony and postpartum hemorrhage following cesarean section under epidural or spinal anaesthesia. The material supplied under this specification is research-grade and is not intended for human administration. Knowlux supplies this compound strictly for laboratory investigation of oxytocin receptor pharmacology, uterine smooth muscle biology, and structure-activity relationships within the oxytocin/vasopressin peptide family.

2. Structural Profile and Receptor Pharmacology

Carbetocin incorporates three structural modifications relative to oxytocin: (i) a butyryl group at the N-terminus, (ii) O-methylation of the tyrosine at position 2, and (iii) a thioether linkage between the butyryl group and the cysteine residue in place of the disulfide bridge. These modifications protect the peptide from aminopeptidase and disulfide-reducing degradation, contributing to a longer duration of action than oxytocin in uterotonic assays. Unlike the vasopressin analogues in the Arg8/Lys8/Orn8 series, Carbetocin retains selectivity for the oxytocin receptor over the vasopressin V1a and V2 subtypes, making it a pharmacological tool for discriminating oxytocin-mediated effects in mixed receptor expression systems. KEGG lists Carbetocin under the target-based classification of drugs as an OXTR agonist within the rhodopsin family of G protein-coupled receptors.

3. Research Applications

Published pharmacological characterizations and documented protocols describe the following research applications:

• Oxytocin receptor (OXTR) binding and functional assays (calcium mobilization, smooth muscle contraction)

• Uterine myometrial contractility studies in obstetric pharmacology models

• Structure-activity relationship comparisons between oxytocin, Carbetocin, and vasopressin analogues

• Peptide stability studies examining thioether versus disulfide constraints

• Reference standard development for HPLC and LC-MS analytical methods

These descriptions are derived from published research and are provided for scientific reference only. They do not constitute clinical guidance or dosing recommendations.

Quality Control

Solubility and Handling

Solubility: Carbetocin Acetate is soluble in water. Krackeler and Sigma-Aldrich list DMSO solubility as slight for the Sigma/SML0748 catalogue item. The high aqueous solubility is consistent with the peptide's polar character and its intended use in aqueous obstetric formulations. For stock solutions, water or buffered saline is the preferred solvent. DMSO is feasible for applications requiring anhydrous conditions, but solubility is limited and should be confirmed empirically on the specific lot. Prepare solutions fresh and aliquot to avoid repeated freeze-thaw cycles.

Handling Precautions: Use powder-handling containment (glove box or fume hood with particulate control). Avoid inhalation of fine powder. Wear nitrile gloves, lab coat, and eye protection. The thioether linkage is less susceptible to reduction than a disulfide bridge, but the methionine-equivalent thioether and the O-methyl tyrosine residue should still be protected from prolonged exposure to strong oxidizing conditions. Follow institutional chemical hygiene plans for research peptides.

Storage and Stability

Documentation Support

Per lot: COA, MSDS, certificate of origin, HPLC chromatogram, and mass spectrometry data. Acetate content, water content, peptide content, and specific optical rotation data available on request. Custom specifications and third-party inspection can be arranged on a project basis.

About Knowlux

Knowlux Biotechnology is a GMP-oriented manufacturer and supplier of peptides, APIs and fine-chemical research compounds, operating from Hubei, China. We serve research groups, CDMOs and distributors in more than 40 countries, and support contract synthesis, custom packaging and technical documentation requests.

Compliance Statement

FOR RESEARCH USE ONLY. NOT FOR HUMAN USE. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE.

This product is supplied for laboratory research use only. It is not for human or animal administration, not for diagnostic or therapeutic use, not for retail sale, and not for personal use. Carbetocin is an approved medicinal product in certain jurisdictions for specific obstetric indications; however, the material offered under this specification is research-grade and is not intended for clinical use. The purchaser is responsible for verifying product specifications against their specific research requirements and for compliance with all applicable institutional, local, and national regulations governing research chemical acquisition, storage, and use. Research context statements are for scientific reference only and do not constitute medical advice, promotional claims, or dosing guidance.

Data Verification Notes: The molecular formula C45H69N11O12S and molecular weight 988.16 g/mol (free peptide) are confirmed by KEGG, LGC/TRC, Selleck, InvivoChem, TargetMol, and PeptideDB. The sequence Butyryl-MeOTyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 with a thioether linkage between the butyryl group and Cys is confirmed by ChemicalBook, CPhI, and Creative Peptides. CAS 37025-55-1 is applied to both the free peptide and the acetate salt in commercial listings; Sigma-Aldrich explicitly annotates it as free base with the empirical formula C45H69N11O12S.xC2H4O2. The monoacetate molecular weight of approximately 1048.21 (C47H73N11O14S) appearing in some listings is noted as an acetate-inclusive value rather than a conflicting structural assignment. One ChemicalBook entry shows a molecular formula of C43H66N12O12S2 with MW 988.16; this formula contains one additional nitrogen and two sulfur atoms relative to the consensus C45H69N11O12S and is treated as a data entry error rather than adopted. The quality control specifications are drawn from ChemicalBook and CPhI supplier listings and corroborated by the LGC/TRC (99.43% HPLC) and Selleck (99.86% HPLC) COA data. The specific optical rotation reference range (-38.0 to -42.0 degrees) is from a ChemicalBook supplier entry and is provided as an optional orthogonal identity check.

Formatting Note: All formulas, sequences, and comparison operators use plain ASCII notation to prevent character corruption on the platform. MeOTyr is rendered as Y(Me) in the one-letter sequence and as MeOTyr in the three-letter description to avoid non-ASCII character risk. Section headings, table alignment, and spacing follow the approved product detail pattern. No trailing spaces or non-breaking characters are used; tables use consistent pipe alignment.