Retatrutide (development code LY3437943; catalog code GLP-3R at Pepitiva) is a single synthetic peptide that activates three hormone receptors at once: the glucose-dependent insulinotropic polypeptide...
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Certificate of Analysis included with every order.
Technical Specifications
Purity
≥98%
Form
Lyophilized powder
Storage
-20°C
Molecular Weight
4731.34 Da (C221H342N46O68)
Sequence
YXQGTFTSDYSILLDKKAQXAFIEYLLEGGPSSGAPPPS (modified peptide; X = non-coded residues)
CAS Number
2381089-83-2
About Retatrutide (GLP-3R)
Retatrutide (development code LY3437943; catalog code GLP-3R at Pepitiva) is a single synthetic peptide that activates three hormone receptors at once: the glucose-dependent insulinotropic polypeptide receptor (GIPR), the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR).[1] It was discovered and is being developed by Eli Lilly and Company, and it is the most studied member of the "triple agonist" class in metabolic research. Pepitiva supplies retatrutide as a lyophilized powder (≥98% purity, CAS 2381089-83-2) for in vitro and preclinical research.[8]
Why a triple agonist matters to researchers
Earlier incretin compounds act on one receptor (GLP-1R, as with semaglutide) or two (GIPR and GLP-1R, as with tirzepatide). Retatrutide adds glucagon receptor activity. In the discovery work, the GIPR and GLP-1R components reduced food intake while the GCGR component increased energy expenditure in obese mice, and the two effects added together.[1] That makes retatrutide a reference compound for separating the intake and expenditure sides of energy balance in experimental models.
Development status
Retatrutide remains an investigational compound under clinical development for type 2 diabetes, obesity and related conditions. The first phase 3 results were published in 2026.[6]
For research use only. Not for human consumption.
Quality & Storage
≥98% purity. Lyophilized powder. Storage: -20°C. For research purposes only.
Mechanism of Action
Retatrutide is one peptide chain with agonist activity at three class B G protein-coupled receptors. In vitro it shows balanced activity at GCGR and GLP-1R and stronger activity at GIPR.[1] Structural studies have since examined how a single peptide engages all three receptors.[7]
GLP-1R: glucose-dependent insulin secretion and reduced food intake.
GIPR: a second incretin pathway that adds to the GLP-1R effect on intake.
GCGR: increased energy expenditure, the component that distinguishes retatrutide from dual agonists.[1]
Pharmacokinetics
In the phase 1b study, exposure rose in proportion to dose and the half-life was about 6 days, consistent with once-weekly administration in clinical protocols.[2] In a single-dose study, the reduction in body weight persisted up to day 43.[1]
Molecular data
Formula C221H342N46O68, molecular weight 4731.34 Da. The sequence contains non-coded amino acids, shown as X in the one-letter code.[8]
Research Applications
Clinical research to date
Phase 1b, type 2 diabetes (2022): 72 participants over 12 weeks. Glucose and HbA1c fell significantly in the three highest dose groups, and body weight reduction appeared dose dependent.[2]
Phase 2, obesity (2023): 338 adults over 48 weeks. Mean body weight change reached −24.2% in the highest dose group against −2.1% with placebo. Gastrointestinal events were the most common adverse events and were dose related.[3]
Phase 2, type 2 diabetes (2023): 281 participants. HbA1c reductions were significantly greater than placebo at all but the lowest dose, and body weight fell by up to about 17% at 36 weeks.[4]
Body composition substudy (2025): measured by DXA, total fat mass fell by up to 26.1% at 36 weeks, against 4.5% with placebo.[9]
Liver fat substudy (2024): 98 participants with steatotic liver disease. At 24 weeks, relative liver fat fell by up to 82.4%, and most participants in the higher dose groups reached normal liver fat (<5%).[5]
Phase 3, TRANSCEND-T2D-1 (2026): 537 adults with type 2 diabetes over 40 weeks. HbA1c fell by up to 1.94% and body weight by up to 15.3%, against 0.81% and 2.6% with placebo.[6]
Laboratory research applications
Receptor pharmacology: signaling and bias at GIPR, GLP-1R and GCGR, alone or with selective antagonists to isolate each arm.
Energy balance models: separating reduced intake from increased energy expenditure in rodent studies.[1]
Hepatic lipid metabolism: liver fat and steatosis models, building on the clinical liver substudy.[5]
Adipocyte biology: lipolysis in differentiated human adipocytes has been studied with retatrutide in vitro.[10]
Comparative incretin studies: single, dual and triple agonism side by side with semaglutide (GLP-1R) and tirzepatide (GLP-2T) (GIPR/GLP-1R), or alongside the amylin analogue cagrilintide, which acts on a separate satiety pathway. For locally acting adipose research, see CBL-514.
The clinical findings above come from studies of the investigational drug and are summarized as scientific background only. This product is sold for laboratory research and is not intended for human or veterinary use.
Storage & Handling Guidelines
Proper storage and handling are essential to maintain peptide integrity and ensure reliable research results. All Pepitiva Biolabs peptides are supplied as lyophilized (freeze-dried) powder, which provides excellent long-term stability when stored correctly. Store lyophilized peptides at -20°C for long-term storage or 2-8°C for short-term use. Once reconstituted, peptide solutions should be stored at 2-8°C and used within the timeframe specified in the product documentation. Always use sterile bacteriostatic water for reconstitution and handle peptides in a clean laboratory environment to prevent contamination. Avoid repeated freeze-thaw cycles, as thermal stress can cause peptide degradation and loss of biological activity.
Quality Control & Certification
This product is manufactured under strict quality control protocols and has been verified through comprehensive analytical testing. Each batch undergoes reverse-phase HPLC analysis for purity determination and electrospray ionization mass spectrometry (ESI-MS) for molecular identity confirmation. A detailed Certificate of Analysis (COA) is available for download, documenting purity percentage, molecular weight verification, appearance, and recommended storage conditions. Pepitiva Biolabs maintains batch-level traceability from synthesis through delivery, ensuring complete transparency and quality assurance for your research.
Frequently Asked Questions
What is GLP-3R?
GLP-3R is Pepitiva's catalog code for retatrutide (LY3437943), a triple agonist of the GIP, GLP-1 and glucagon receptors.
How is retatrutide different from tirzepatide?
Tirzepatide acts on two receptors (GIPR and GLP-1R). Retatrutide adds a third, the glucagon receptor, which in preclinical studies increased energy expenditure on top of the reduced food intake driven by the incretin receptors. See Tirzepatide (GLP-2T).
Who developed retatrutide?
Eli Lilly and Company, which published its discovery in 2022 and sponsors its clinical program.
Is retatrutide approved?
Retatrutide is an investigational compound. The first phase 3 trial results were published in 2026, and it remains under clinical development.
What is the molecular weight of retatrutide?
4731.34 Da, with the molecular formula C221H342N46O68 (KEGG DRUG D12430).
What is the half-life of retatrutide?
About 6 days in the phase 1b clinical study, which is why clinical protocols used once-weekly administration.
How should retatrutide be stored?
Keep the lyophilized powder at −20 °C, protected from light and moisture.
Is this product approved for human use?
No. This product is intended exclusively for in vitro scientific research and laboratory use. It is not approved for human or veterinary use, not intended for diagnostic or therapeutic purposes, and should not be administered to humans or animals under any circumstances.
How do I reconstitute this peptide?
Add sterile bacteriostatic water slowly to the vial, directing the stream against the glass wall rather than directly onto the lyophilized powder. Gently swirl the vial until the powder is fully dissolved — do not shake vigorously. The recommended reconstitution volume depends on your desired concentration. Refer to the product documentation for specific guidance.
Can I get a Certificate of Analysis (COA)?
Yes. A Certificate of Analysis is included with every order and is also available for download from the product page. The COA documents HPLC purity, mass spectrometry identity confirmation, batch number, production date, and storage recommendations.
Scientific 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. PubMed
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. PubMed
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. PubMed
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. PubMed
Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat Med. 2024;30(7):2037-2048. PubMed
Bajaj HS, Welch M, Shah P, et al. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial. Lancet. 2026;407(10546):2402-2413. PubMed
Li W, Zhou Q, Cong Z, et al. Structural insights into the triple agonism at GLP-1R, GIPR and GCGR manifested by retatrutide. Cell Discov. 2024;10(1):77. PubMed
KEGG DRUG D12430: Retatrutide (USAN). Formula C221H342N46O68, molecular weight 4731.34, CAS 2381089-83-2. Source
Coskun T, Wu Q, Schloot NC, et al. Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial. Lancet Diabetes Endocrinol. 2025;13(8):674-684. PubMed
Regmi A, Roell W. Differentiation of human subcutaneous adipocytes and measurement of lipolytic function induced by GIP or LY3437943. STAR Protoc. 2023. PubMed
Sources are peer-reviewed publications indexed in PubMed and trial registrations on ClinicalTrials.gov. Each citation was checked against its PubMed record.
For research use only. Not for human consumption.
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