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What is Retatrutide? Triple Agonist Research Peptide Explained
Updated May 2026 · By the Onyx Biolabs Research Team · For laboratory research use only
Retatrutide (LY3437943) is a synthetic 39-amino-acid triple agonist research peptide that activates three metabolic receptors simultaneously: GLP-1, GIP, and glucagon. It is the first known compound to engage all three pathways at once, and is studied in preclinical models for metabolic, weight-management, and energy-expenditure research.
How retatrutide works
Retatrutide is a chemically modified 39-amino-acid peptide engineered to bind and activate three distinct G-protein-coupled receptors involved in metabolic regulation. By engaging GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) receptors, retatrutide increases insulin secretion and reduces appetite in research models. Its third activity — agonism at the glucagon receptor — increases energy expenditure, distinguishing it from dual agonists like tirzepatide.
The triple-receptor design means retatrutide drives weight loss in preclinical studies through two mechanisms running in parallel: reduced caloric intake (via GLP-1 / GIP appetite suppression) and increased caloric burn (via glucagon-driven thermogenesis). This is why retatrutide is described as a “triple agonist” or “tri-agonist” in the literature.
Retatrutide molecular properties
- Molecular weight: ~4,731 Da (theoretical, 39 amino acids)
- Sequence length: 39 amino acids
- Half-life (preclinical): ~6 days in rodent models, supporting weekly dosing protocols
- Receptor targets: GLP-1R, GIPR, GCGR
- Storage: Lyophilized at room temperature short-term, freezer (-20°C) long-term; reconstituted at 2–8°C for ~28 days
Research applications
- Obesity and metabolic disease models — primary research focus given the triple-receptor mechanism
- Energy expenditure studies — glucagon receptor agonism is uniquely valuable for thermogenesis research
- Insulin sensitivity research — GLP-1 + GIP combined activity
- Comparative metabolic-peptide studies — often researched alongside tirzepatide (dual agonist) and semaglutide (single agonist)
How retatrutide differs from other GLP-1 research peptides
The three peptides most commonly compared in metabolic research are retatrutide, tirzepatide, and semaglutide. Semaglutide is a single agonist (GLP-1 only). Tirzepatide is a dual agonist (GLP-1 and GIP). Retatrutide is the only triple agonist (GLP-1, GIP, and glucagon). The added glucagon agonism is what gives retatrutide higher peak weight-loss effect in preclinical models — but it also introduces additional metabolic complexity that researchers should account for.
Where to source research-grade retatrutide
Onyx Biolabs sells Retatrutide research peptide in 5 mg, 10 mg, 15 mg, and 20 mg vials with verified >99% purity. Every batch is independently tested by Kovera Labs for both HPLC purity and Mass Spec identity confirmation. View current COAs.
Frequently asked questions
What is retatrutide?
Retatrutide (development code LY3437943) is a synthetic 39-amino-acid peptide that simultaneously activates three metabolic receptors: GLP-1, GIP, and glucagon. It is researched in preclinical models for metabolic, weight-management, and energy-expenditure applications.
What is the molecular weight of retatrutide?
Approximately 4,731 Daltons (theoretical mass for the 39-amino-acid sequence). On a Mass Spec report, the observed mass should match this within +/- 1 Da to confirm identity.
How is retatrutide different from tirzepatide?
Tirzepatide is a dual agonist (GLP-1 and GIP receptors). Retatrutide is a triple agonist (GLP-1, GIP, and glucagon receptors). The added glucagon agonism in retatrutide drives additional energy expenditure that tirzepatide does not.
What concentration should I reconstitute retatrutide at?
Most research protocols use 2–3 mL of bacteriostatic water per 10 mg vial, giving final concentrations of 5 mg/mL or 3.33 mg/mL. Use the peptide calculator for exact volumes.
How long does reconstituted retatrutide stay stable?
Approximately 28 days at 2–8°C in the refrigerator. Do not freeze reconstituted vials.
Is retatrutide legal to purchase in the United States?
Retatrutide is sold legally in the United States as a research chemical for in-vitro and laboratory research use only. It is not approved by the FDA for human consumption.
Where can I buy research-grade retatrutide?
Onyx Biolabs sells retatrutide in 5/10/15/20 mg vials with independent Kovera Labs COAs at /product/retatrutide-peptide/.
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Disclaimer
For research, laboratory, or analytical use only. The compound discussed is not approved for human or animal consumption. Statements on this page have not been evaluated by the FDA. Onyx Biolabs is a chemical supplier, not a compounding pharmacy or 503A/503B facility.