Retatrutide
Molecular Research Profile ยท Target purity > 99.0% ยท Half-life ~6 days
Triple GIP/GLP-1/Glucagon receptor agonist showing unprecedented metabolic acceleration and weight management properties in clinical research.
Retatrutide Molecular Formula, Structure & Chemical Identity
Reference identifiers researchers use to verify that a vial matches what a vendor claims to have shipped. Cross-check these values against any Certificate of Analysis before accepting a purity figure.
| Molecular Formula | C221H342N46O68 |
|---|---|
| Molecular Weight | 4731.4 g/mol |
| CAS Number | 2381089-83-2 |
| Amino Acid Count | 39 |
| Amino Acid Sequence | Tyr-Aib-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Ile-MeLeu-Leu-Asp-Lys-Lys-Aib-Gln-Ala-Aib-Phe-Ile-Glu-Tyr-Leu-Leu-Glu-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser |
| Also Known As | LY3437943, LY-3437943, Triple G agonist |
| PubChem CID | 171934787 ↗ |
NOTE: PubChem CID 171934787 is the sodium salt entry; the formula shown is the free peptide acid.
Identifiers verified against the NIH PubChem compound database. Molecular weights independently recalculated from the molecular formula using IUPAC 2021 standard atomic weights.
How to Read a Retatrutide Certificate of Analysis
A COA is only meaningful if the identifiers on it match the compound you ordered. Four checks, in order.
- 1. Identity โ does the formula match?The COA header should state C221H342N46O68 and a molecular weight near 4731.4 g/mol, with CAS 2381089-83-2. A mismatch means you are not looking at a COA for this compound.
- 2. Purity โ HPLC chromatogram, not just a numberA printed “> 99.0%” with no chromatogram is a marketing claim. Demand the actual HPLC trace: a single dominant peak, labelled retention time, and an integration table. Shoulders or unlabelled side peaks are unreported impurities.
- 3. Mass confirmation โ does MS agree with the formula?Mass spectrometry should report an observed mass consistent with the expected 4731.4 g/mol. Peptides are frequently reported as multiply charged ions, so the raw m/z value will be lower than the neutral mass. An unexplained offset is a red flag.
- 4. Provenance โ who signed it, and for which batch?A valid COA names the testing laboratory, carries a batch or lot number that matches your vial label, and is dated. A vendor-produced PDF with no lab identity and no batch number is not third-party evidence.
Full methodology in ourguide to the 5 COA red flags researchers miss, or verify the reconstitution math with thepeptide reconstitution calculator.
Mechanism of Action
Retatrutide is a single-peptide triple agonist targeting the glucose-dependent insulinotropic polypeptide (GIP) receptor, the glucagon-like peptide-1 (GLP-1) receptor, and the glucagon (GCG) receptor simultaneously. This triple targeting sets it apart from earlier single- and dual-agonist weight-management peptides such as semaglutide (GLP-1 only) and tirzepatide (GIP/GLP-1).
The glucagon receptor activation is the key differentiator: while GLP-1 agonism suppresses appetite and GIP agonism enhances insulin secretion, glucagon agonism directly increases resting energy expenditure and hepatic lipid oxidation. In rodent and non-human primate models, this translated to greater fat-mass loss compared to GLP-1 monotherapy, even at equivalent caloric intake โ suggesting a genuine metabolic-acceleration component beyond appetite suppression alone.
Binding affinity studies indicate that retatrutide's activity at the human GCG receptor is roughly balanced with its GLP-1 receptor potency, yielding a profile that simultaneously reduces energy intake and increases energy output. The ~6-day half-life (conferred by a fatty-acid side chain promoting albumin binding) supports once-weekly administration in research protocols.
Research History & Context
Retatrutide (LY3437943) was developed by Eli Lilly and entered Phase 2 clinical trials (NCT04881760) in 2021โ2023 for obesity and type 2 diabetes. The Phase 2 data, published in the New England Journal of Medicine in June 2023, reported mean body-weight reductions of up to 24.2% at 48 weeks in the highest-dose cohort โ substantially exceeding the 15โ21% reductions reported for tirzepatide and semaglutide in comparable trial settings.
Phase 3 trials (TRIUMPH program) were initiated in mid-2023 and are ongoing as of 2026. The research-grade peptide has become widely available through independent analytical laboratories and third-party-verified suppliers, making it one of the most actively studied research peptides in the metabolic and longevity space.
Storage & Handling
Lyophilized (freeze-dried) retatrutide powder should be stored at -20ยฐC in a desiccated, light-protected environment for long-term stability (>12 months). Short-term storage (up to 4 weeks) at 2โ8ยฐC is acceptable for lyophilized vials awaiting reconstitution.
After reconstitution with bacteriostatic water (0.9% benzyl alcohol), the solution should be kept at 2โ8ยฐC and used within 28 days. Do not freeze reconstituted peptide solutions, as ice-crystal formation can denature the tertiary protein structure and significantly reduce bioactivity. Avoid repeated freeze-thaw cycles of the lyophilized powder โ aliquot into single-use research vials where possible.
Comparison: Retatrutide vs. Tirzepatide vs. Semaglutide
| Property | Retatrutide | Tirzepatide | Semaglutide |
|---|---|---|---|
| Receptors | GIP + GLP-1 + GCG | GIP + GLP-1 | GLP-1 only |
| Energy Expenditure | โโ (glucagon-driven) | โ (minimal) | โ (minimal) |
| Half-Life | ~6 days | ~5 days | ~7 days |
| Phase 2 Weight Loss | ~24% at 48 wks | ~21% at 72 wks | ~15% at 68 wks |
Reconstitution & Research Dosing
For Retatrutide, the standard laboratory reconstitution is 2.0 ml BAC water for 10mg vial. A typical research study window uses 1.0 mg - 4.0 mg / week.
When preparing your research solution, use sterile bacteriostatic water (not sterile water for injection) to maintain antimicrobial protection during the 28-day usage window. Draw the BAC water slowly along the vial wall โ never jet it directly onto the lyophilized powder โ to avoid mechanical shear stress on the peptide. Swirl gently; do not shake.
Use the Reconstitution Calculator for exact syringe units →Audited Vendors Stocking Retatrutide
Each review checks whether the testing lab is named and whether COAs can be verified at the issuing lab.
Related Retatrutide Research
Retatrutide FAQ
QWhat is the molecular formula of Retatrutide?
Retatrutide has the molecular formula C221H342N46O68 and a molecular weight of approximately 4731.4 g/mol. Its CAS registry number is 2381089-83-2. It is a 39-residue peptide with the sequence Tyr-Aib-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Ile-MeLeu-Leu-Asp-Lys-Lys-Aib-Gln-Ala-Aib-Phe-Ile-Glu-Tyr-Leu-Leu-Glu-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser.
QHow do you verify a Retatrutide Certificate of Analysis?
Check four things in order. First, identity: the COA must state C221H342N46O68 and CAS 2381089-83-2. Second, purity: require the actual HPLC chromatogram with retention time and integration table, not just a printed percentage. Third, mass confirmation: the mass spectrometry result must agree with the expected molecular weight of 4731.4 g/mol, allowing for multiply charged ions. Fourth, provenance: the COA must name the testing laboratory and carry a batch number matching your vial label.
QWhat purity should Retatrutide be?
Research-grade Retatrutide should meet a purity target of > 99.0%, confirmed by third-party HPLC analysis rather than a vendor self-declaration. A purity claim without an accompanying chromatogram carries no evidential weight.
QWhat is the half-life of Retatrutide?
The reported half-life of Retatrutide is ~6 days. Half-life figures come from published research models and vary with species, route and formulation, so treat them as a reference range rather than a fixed value.
QHow much bacteriostatic water do you add to Retatrutide?
The standard reconstitution for Retatrutide is 2.0 ml BAC water for 10mg vial. When preparing your research solution, use sterile bacteriostatic water (not sterile water for injection) to maintain antimicrobial protection during the 28-day usage window. Draw the BAC water slowly along the vial wall โ never jet it directly onto the lyophilized powder โ to avoid mechanical shear stress on the peptide. Swirl gently; do not shake.
Explore Related Research Compounds
Research Use Only (RUO): Retatrutide is discussed strictly as an in-vitro laboratory research compound. Nothing on this page constitutes human or clinical administration guidance. Always verify purity through independent third-party HPLC/MS analysis before use.