What Is Retatrutide? Research Guide
Definition
Retatrutide (development code LY3437943) is a synthetic 39-amino-acid fatty-acylated peptide, CAS 2381089-83-2, with an average molecular weight near 4731 Da. A single backbone agonizes three receptors — GIP, GLP-1 and glucagon — which is what separates it from the dual and single agonists it is compared against. It is investigational and is not an approved drug.
Key Takeaways
- →Retatrutide (development code LY3437943) is a synthetic 39-amino-acid fatty-acylated peptide, CAS 2381089-83-2, with an average molecular weight near 4731 Da. A single backbone agonizes three receptors — GIP, GLP-1 and glucagon — which is what separates it from the dual and single agonists it is compared against.
- →Available for in-vitro research at ≥99% HPLC-verified purity from Peptide.Express.
- →Certificate of Analysis included with every order. Same-day US shipping.
Retatrutide Specifications
| Property | Value |
|---|---|
| Compound | Retatrutide |
| CAS Number | 2381089-83-2 |
| Molecular Weight | 4731 Da |
| Sequence / Structure | Synthetic 39-amino-acid GIP/GLP-1/glucagon triple agonist (fatty-acylated) |
| Mechanism Class | Triple GLP-1 / GIP / glucagon receptor agonist |
| Purity | ≥99% by HPLC, batch-specific CoA included |
Registry records for Retatrutide: Wikidata
Retatrutide Mechanism of Action
Retatrutide is built on a GIP-analog backbone rather than a GLP-1 one, with a C20 fatty diacid attached through a linker so the molecule binds albumin and clears slowly. The third arm is what distinguishes it: agonism at the glucagon receptor, which neither tirzepatide (GIP/GLP-1) nor semaglutide (GLP-1 only) possesses. The three activities are not balanced in the published pharmacology, which describes potent GIP receptor agonism with lower relative potency at the GLP-1 and glucagon receptors. The glucagon arm is also the least characterized of the three and the most debated, since agonizing that receptor runs opposite to the direction glucagon signaling is usually framed in glucose research.
Retatrutide Research Applications
Incretin receptor pharmacology, where retatrutide is the tool for asking what glucagon-receptor agonism adds to a GIP/GLP-1 background, with tirzepatide serving as the two-receptor control.
Energy-expenditure models. The glucagon arm is the proposed lever and the reason a triple agonist was designed rather than another GLP-1 analog.
Receptor-selectivity work using cAMP accumulation in cells expressing each of the three receptors separately, which is how relative potency at each is actually resolved.
Comparative incretin panels alongside semaglutide and tirzepatide, which together form a one-, two- and three-receptor series measurable on shared assays.
Retatrutide Storage Requirements
Store lyophilized retatrutide at -20°C (-4°F). Reconstituted, hold at 2-8°C (36-46°F) and use within 30 days. Fatty-acylated peptides of this class self-associate, and aggregation rather than hydrolysis is the failure mode that matters: add diluent gently down the vial wall, do not vortex, and do not refreeze the reconstituted solution.
Retatrutide at Peptide.Express
All Retatrutide sold by Peptide.Express is HPLC-verified at ≥99% purity with a Certificate of Analysis included. Same-day US shipping on orders before 2 PM EST. For in-vitro laboratory research use only.
View Retatrutide Product DetailsFrequently Asked Questions
What is Retatrutide?
Retatrutide, development code LY3437943, is a synthetic 39-amino-acid fatty-acylated peptide that activates the GIP, GLP-1 and glucagon receptors from a single backbone. Its CAS registry number is 2381089-83-2 and its average molecular weight is approximately 4731 Da. It is studied in incretin-receptor pharmacology and metabolic research, for laboratory use only.
What is the difference between Retatrutide, tirzepatide and semaglutide?
Receptor coverage. Semaglutide is a single GLP-1 receptor agonist. Tirzepatide is a dual GIP/GLP-1 agonist. Retatrutide adds a third activity at the glucagon receptor. All three are fatty-acylated peptides engineered for albumin binding and slow clearance, so the pharmacokinetic strategy is shared and the number of receptors engaged is what separates them.
Is Retatrutide FDA approved?
No. Retatrutide is investigational. It has been studied in registered clinical trials but has not been approved by the FDA or any other regulator, and no retatrutide drug product exists in any market. Research-grade retatrutide is not a medicine and is sold for in-vitro laboratory research only.
What is the molecular weight and CAS number of Retatrutide?
Retatrutide has an average molecular weight of approximately 4731 Da and CAS registry number 2381089-83-2. No molecular formula is stated on this page: none could be confirmed against an authoritative chemical registry at the time of writing, and an unverified formula for a fatty-acylated 39-mer is not worth publishing as fact.
Where can I buy Retatrutide for research?
Research-grade Retatrutide is available from Peptide.Express at ≥99% HPLC-verified purity with a Certificate of Analysis included. Visit peptide.express/catalog/retatrutide for details.
References
- Jastreboff AM, Kaplan LM, Frías JP, et al. "Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial." New England Journal of Medicine, 2023. Read the retatrutide Phase 2 trial in NEJM
- "Retatrutide — A Game Changer in Obesity Pharmacotherapy." Review of the triple GLP-1/GIP/glucagon receptor agonist pharmacology and the trial evidence available prior to Phase 3 readout. Read the retatrutide obesity pharmacotherapy review on PMC
- "Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist." Systematic review of the published retatrutide efficacy and adverse-event data. Read the retatrutide efficacy and safety review on PMC
- 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 Metabolism. 2022. Read the Coskun 2022 retatrutide discovery and receptor pharmacology paper in Cell Metabolism
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How This Page Is Sourced
Molecular identity on this page — name, CAS number, molecular formula and molecular weight — is resolved from a single internal entity record and checked against primary registries (PubChem, CAS Common Chemistry) rather than retyped per page. A field with no verified value is left out instead of estimated. Literature is cited to a DOI, PMID or PMCID permalink so every reference resolves to the specific record it names.