For laboratory research use only. Not for human or veterinary use.
Research use only. Peptide.Express supplies retatrutide only as a reference material for in-vitro laboratory research. It is not a drug, food, or cosmetic. Retatrutide is investigational; not approved by FDA for any use. See Is retatrutide FDA approved?.
Short answer. Retatrutide (development code LY3437943) is a synthetic, 39-residue, lipidated peptide. In laboratory studies it acts as an agonist at three class B G-protein-coupled receptors: the glucose-dependent insulinotropic polypeptide receptor (GIPR), the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR) [1]. Its discovery and preclinical characterisation were published in 2022 by researchers at Eli Lilly and Company [1]. Peptide.Express is not affiliated with, endorsed by or a supplier for Eli Lilly and Company. Because it acts on three receptors, the research literature calls it a "triple agonist" [1][2]. The informal labels "Reta" and "GLP-3" also appear in commercial use; there is no hormone named GLP-3.
Key facts at a glance
| Property | Value | Source |
|---|---|---|
| International Nonproprietary Name (INN) | Retatrutide | ChEMBL CHEMBL5095485; GtoPdb ligand 13769 |
| Development code | LY3437943 | [1]; ChEMBL CHEMBL5095485 |
| CAS Registry Number | 2381089-83-2 | Wikidata Q120468350 (P231) |
| Molecular formula | C221H342N46O68 | PubChem CID 171390338 |
| Molecular weight | ≈4731 g/mol | PubChem CID 171390338 |
| Peptide length | 39 amino acids | PubChem CID 171390338 (structure record) |
| Receptor targets | GIPR, GLP-1R, GCGR (agonist, in vitro) | [1] |
| Lipidation | C20 fatty diacid (icosanedioic acid) attached via a γ-Glu / AEEA linker to the lysine side chain at position 17 | PubChem CID 171390338 (IUPAC name) |
| Non-coded residues | α-aminoisobutyric acid (Aib) at positions 2 and 20; α-methyl-leucine at position 13 | PubChem CID 171390338 (IUPAC name) |
| C-terminus | Amide (Ser-NH2) | PubChem CID 171390338 (IUPAC name) |
| Regulatory status | Investigational; not approved by FDA for any use | Is retatrutide FDA approved? |
| Peptide.Express sourcing specification | Lyophilized powder; ≥99% HPLC purity sourcing specification; measured results are on each lot's certificate of analysis | Retatrutide certificates of analysis |
Names and identifiers: Reta, GLP-3 and LY3437943
Researchers and procurement teams meet several names for the same molecule:
- Retatrutide is the INN. Use it in publications, lab notebooks and purchase records.
- LY3437943 is the development code. It appears in the discovery paper [1], the phase 1b paper [2] and the titles of the registered Phase 3 studies on ClinicalTrials.gov [5].
- CAS 2381089-83-2 is the CAS Registry Number. It is a reliable key for matching a vial label, a certificate of analysis and a safety data sheet to one another.
- "Reta" is an informal shortening. "GLP-3" is a commercial nickname, not a pharmacological name: there is no hormone named GLP-3, and no GLP-3 receptor. See What is GLP-3? The retatrutide nickname explained.
- Database identifiers: IUPHAR/BPS Guide to Pharmacology ligand 13769, PubChem CID 171390338, ChEMBL CHEMBL5095485 and Wikidata Q120468350.
A practical note for labs: the vial label, the COA and the SDS should carry the same name, CAS number and lot number. If one of them uses only a nickname such as "GLP-3" and gives no CAS number, ask for corrected documentation before the material enters an experiment.
Why exact identifiers matter in research records. Retatrutide, tirzepatide and semaglutide are lipidated peptides of broadly similar size that are often referred to by abbreviations. Recording the INN, the CAS number, the lot number and the COA reference in every experiment log makes results traceable and lets any anomalous result be checked against the exact batch that produced it.
Molecular structure
Retatrutide is a single-chain peptide of 39 residues with a C-terminal amide (PubChem CID 171390338). Three structural features matter most for analysis:
- Non-coded residues. Aib at positions 2 and 20 and α-methyl-leucine at position 13 (PubChem CID 171390338).
- Fatty-diacid lipidation. A C20 fatty diacid is attached through a γ-Glu / AEEA linker to the side chain of the lysine at position 17 (PubChem CID 171390338).
- C-terminal amide. This affects charge state and chromatographic behaviour.
Analytical implications. Because of the lipid chain and the ≈4.7 kDa mass, retatrutide is relatively hydrophobic on reversed-phase HPLC, and in electrospray mass spectrometry it appears as multiple charge states, so identity is normally confirmed by deconvoluting the spectrum to the intact mass. A COA for retatrutide should therefore report an HPLC purity figure with the chromatogram and an MS identity result consistent with the theoretical mass. See How to read a retatrutide COA below.
Receptor pharmacology: what "triple agonist" means
Retatrutide's targets are three related receptors in the class B1 (secretin-family) GPCR group:
| Receptor | Endogenous ligand | Receptor family |
|---|---|---|
| GIPR | Glucose-dependent insulinotropic polypeptide | Class B1 GPCR |
| GLP-1R | Glucagon-like peptide-1 | Class B1 GPCR |
| GCGR | Glucagon | Class B1 GPCR |
In the discovery report, Coskun and colleagues characterised LY3437943 in vitro and reported agonist activity at all three receptors, with comparable GCGR and GLP-1R activity and greater GIPR activity, that is, an unbalanced profile [1]. Relative potency values depend on assay format, receptor species and cell background; readers who need them should consult the primary paper [1] directly. Limits of this evidence: these are in-vitro and animal-model findings from the sponsor's own laboratories; they describe receptor activity under specific assay conditions and do not establish any effect, safety or use in people.
How it differs from single- and dual-receptor comparators. In receptor-pharmacology terms, semaglutide is a GLP-1R agonist, tirzepatide is a dual GIPR/GLP-1R agonist, and retatrutide adds GCGR agonism to the GIPR/GLP-1R pair [1]. Side-by-side receptor tables: Retatrutide vs Tirzepatide and Retatrutide vs Semaglutide.
Where retatrutide is used in laboratory research
Typical in-vitro research areas for a class B1 GPCR multi-agonist include:
- Receptor pharmacology: concentration–response and selectivity studies across GIPR, GLP-1R and GCGR.
- Signalling studies: cAMP and β-arrestin readouts, receptor internalisation and desensitisation.
- Analytical method development: HPLC and LC-MS methods for lipidated peptides.
- Cell-culture signalling models: hepatocyte, adipocyte and islet-cell systems.
These are laboratory research applications only. Nothing on this page describes or implies any use in humans or animals.
The published retatrutide research record (citation map)
This is a reading list of the primary literature and registry entries. It names studies neutrally and makes no claim about their outcomes. Human studies listed here are investigational studies conducted by the sponsor under regulatory oversight; their reported endpoints are not presented here, and nothing in them makes research-grade material suitable for human use.
| Year | Publication / registry entry | Type | Subject of the study |
|---|---|---|---|
| 2022 | Coskun T, et al. Cell Metab. 34(9):1234–1247.e9 [1] | Discovery / preclinical | Design and in-vitro and animal characterisation of LY3437943 |
| 2022 | Urva S, et al. Lancet 400(10366):1869–1881 [2] | Phase 1b (investigational) | Multiple-ascending-dose pharmacology study |
| 2023 | Jastreboff AM, et al. N Engl J Med 389(6):514–526 [3] | Phase 2 (investigational) | Randomised, placebo-controlled study |
| 2023 | Rosenstock J, et al. Lancet 402(10401):529–544 [4] | Phase 2 (investigational) | Randomised, placebo- and active-controlled study |
| 2023– | ClinicalTrials.gov registry entries [5] | Phase 3 (investigational) | TRIUMPH-1 (NCT05929066), TRIUMPH-2 (NCT05929079), TRIUMPH-3 (NCT05882045), TRIUMPH-4 (NCT05931367), TRANSCEND-T2D-1 (NCT06354660); each listed with status "Completed" as of 25 October 2026 |
Regulatory status
Retatrutide is investigational; not approved by FDA for any use. As of 25 October 2026 the FDA has not approved it for any indication. Material sold as a research chemical is not an investigational drug product and is not a substitute for one. Full detail: Is retatrutide FDA approved?.
Storage and handling (laboratory)
- Store and handle according to the Retatrutide SDS and the storage conditions printed on the lot's certificate of analysis.
- Allow a sealed vial to reach room temperature before opening to limit condensation.
- Handle with standard laboratory PPE in a laboratory setting.
Documentation: COA and SDS
When reviewing any retatrutide certificate of analysis, check:
- Identity by mass spectrometry: an MS result consistent with the ≈4731 Da intact mass, with the name and CAS 2381089-83-2 stated.
- Purity by HPLC: the measured HPLC purity percentage with the chromatogram and a method summary.
- Lot match: the lot number on the certificate matches the vial label, with a test date.
- Issuing laboratory: the laboratory that performed the testing is named.
- Verification: where the issuing laboratory provides a verification method (for example, a certificate lookup), confirm the certificate with that laboratory.
Where a laboratory tested for endotoxin, the result is on that lot's certificate.
View current certificates: Retatrutide certificates of analysis. Safety data: Retatrutide SDS.
Retatrutide at Peptide.Express
Peptide.Express supplies retatrutide as a lyophilized research reference material sourced to a ≥99% HPLC purity specification; the measured purity for each lot is on its certificate of analysis. View the retatrutide research listing. Sale is restricted to laboratory research purchasers, who must acknowledge research-use-only terms.
Retatrutide glossary: terms used on this page
- Agonist: a ligand that binds a receptor and activates its signalling.
- Class B1 GPCR: the secretin-family G-protein-coupled receptors, which include GIPR, GLP-1R and GCGR.
- Unbalanced agonist: a multi-receptor agonist whose relative activity differs between its targets.
- Aib (α-aminoisobutyric acid): a non-coded amino acid.
- Lipidation: covalent attachment of a fatty-acid chain to a peptide.
- HPLC purity: the percentage of total UV-absorbing peak area attributable to the main peak under a stated method.
- Deconvoluted mass: the intact molecular mass calculated from a multiply-charged electrospray mass spectrum.
- INN: International Nonproprietary Name, the generic name assigned under the World Health Organization programme.
Frequently asked questions
What is retatrutide?
Retatrutide (LY3437943) is a synthetic 39-residue lipidated peptide that acts in vitro as an agonist at the GIP, GLP-1 and glucagon receptors [1]. It is investigational; not approved by FDA for any use.
What is the CAS number of retatrutide?
CAS 2381089-83-2. Its molecular formula is C221H342N46O68 and its molecular weight is approximately 4731 g/mol.
Why is retatrutide called "GLP-3"?
"GLP-3" is an informal commercial nickname. There is no hormone named GLP-3, and no GLP-3 receptor. See What is GLP-3?.
What is the difference between retatrutide, tirzepatide and semaglutide?
Receptor coverage. Semaglutide targets GLP-1R, tirzepatide targets GIPR and GLP-1R, and retatrutide targets GIPR, GLP-1R and GCGR. Retatrutide vs Tirzepatide.
Is retatrutide FDA approved?
No. Retatrutide is investigational; not approved by FDA for any use. Is retatrutide FDA approved?.
What should a retatrutide certificate of analysis include?
Identity by MS consistent with ≈4731 Da, purity by HPLC with the chromatogram, a lot number matching the vial, the test date and the issuing laboratory, and, where that laboratory offers it, a way to verify the certificate with the lab.
Related research
References
- Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept. Cell Metab. 2022;34(9):1234-1247.e9. doi:10.1016/j.cmet.2022.07.013. PMID 35985340.
- Urva S, Coskun T, Loh MT, et al. LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. Lancet. 2022;400(10366):1869-1881. doi:10.1016/S0140-6736(22)02033-5. PMID 36354040.
- Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. doi:10.1056/NEJMoa2301972. PMID 37366315.
- Rosenstock J, Frias J, Jastreboff AM, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA. Lancet. 2023;402(10401):529-544. doi:10.1016/S0140-6736(23)01053-X. PMID 37385280.
- ClinicalTrials.gov records NCT05929066, NCT05929079, NCT05882045, NCT05931367, NCT06354660 (accessed 25 October 2026).
Identifiers: IUPHAR/BPS Guide to Pharmacology ligand 13769 · PubChem CID 171390338 · Wikidata Q120468350 · ChEMBL CHEMBL5095485.
How this page is sourced: Peptide.Express Editorial wrote this page. Identity data come from public chemical databases; scientific statements cite peer-reviewed primary sources. This page makes no therapeutic claims.
This article is for educational and informational purposes only and summarizes published scientific research. It is not medical advice. Compounds discussed are available for laboratory research use only. Consult a qualified professional for any health-related questions.