Retatrutide is among the most closely watched investigational compounds in metabolic research in 2026. Developed by Eli Lilly as part of its TRIUMPH clinical program, this triple receptor agonist is not approved by the FDA for any indication. Its profile as a simultaneous agonist at the GIP, GLP-1, and glucagon receptors has generated significant research interest, and with that interest has come a broader range of vendor quality than exists for more established compounds.
The five vendors compared here are ranked by documentation rigor: third-party COA accessibility, HPLC purity standards, batch traceability, and operational stability. All five carry retatrutide. Not all five documents are documented to the same standard.
What Is Retatrutide (LY3437943)?
Retatrutide (LY3437943) is a synthetic 39-amino acid peptide developed by Eli Lilly. Research suggests it acts as a simultaneous agonist at three metabolic receptors: the glucagon-like peptide-1 receptor (GLP-1R), the glucose-dependent insulinotropic polypeptide receptor (GIPR), and the glucagon receptor (GCGR). Investigations indicate this multi-receptor activity may serve as a model for studying integrated metabolic signaling pathways that single-target compounds cannot replicate in isolation.
In Eli Lilly’s TRIUMPH-1 Phase 3 trial (n=2,339), the compound produced a mean weight loss of 28.3% at 80 weeks in research models without type 2 diabetes. An extension at 104 weeks recorded a mean weight loss of 30.3%, approximately 85 pounds, the deepest figure reported for any metabolic compound in a Phase 3 program to date. Retatrutide remains investigational and is not approved by the FDA for any therapeutic or clinical indication. TRIUMPH-2 and TRIUMPH-3 readouts covering type 2 diabetes and established cardiovascular disease are expected later in 2026.
What to Look for When Sourcing Retatrutide
Retatrutide is a 39-amino acid peptide with a molecular weight of approximately 4,556 Da. Its structural complexity makes purity documentation more critical than for simpler, smaller compounds. A purity figure without a named analytical method is not a COA: it is a claim. HPLC purity of 98% or higher is the accepted minimum standard for research-grade material. Mass spectrometry confirming the correct molecular weight adds a second level of verification and should appear alongside the HPLC figure on the same COA.
Three documentation markers distinguish reliable retatrutide suppliers:
- A batch-specific COA from a named independent laboratory (Janoshik Analytical, MZ Biolabs, and Colmaric Analyticals are the most-cited in the research community)
- HPLC purity at or above 98% with a traceable batch number
- Mass spectrometry confirmation of molecular identity
Vendors pricing retatrutide significantly below market rates without meeting these standards present documentation risk for research designs where compound identity and purity directly affect data quality.
#1. PureRawz
PureRawz carries retatrutide under its LY3437943 catalog entry with MZ Biolabs COA documentation attached at the product level. The listing sits within a broader GLP-1 and metabolic peptide catalog, so complementary compounds (tirzepatide, semaglutide, GIP agonists) are available from the same documented source without switching vendors mid-study.
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#2. Behemoth Labz
Behemoth Labz carries retatrutide in two research formulations: a standard injectable peptide and a nasal spray. Colmaric Analyticals LLC handles independent testing for both, with purity figures consistently returning above 99% HPLC. COAs are posted directly on the product page rather than being available on request.
The availability of a nasal spray formulation is notable for research designs requiring a non-injectable delivery route. Both formulations carry the same batch-specific independent COA standard, making Behemoth Labz the most thoroughly documented supplier for retatrutide research across multiple delivery formats.
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#3. Core Peptides
For researchers whose catalog or budget needs fall outside what PureRawz and Behemoth Labz cover, Core Peptides stocks retatrutide with third-party COA documentation and extended research literature citations on the product page. User review data skews positive, though the operation is newer than the two vendors ranked above it, and the documentation history across a full range of batches is shorter as a result.
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#4. Ascension Peptides
Ascension Peptides appears in multiple 2026 vendor roundups for retatrutide sourcing, with independently tested batches yielding HPLC purity of 98% or higher. COAs are published on product pages rather than being available on request. The catalog is narrower in scope, but for retatrutide specifically, the testing documentation record is among the most consistent from a domestic supplier.
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#5. SwissChems
SwissChems lists retatrutide within a catalog of 60 or more peptide products. For this compound specifically, COA documentation is not consistently posted on the product page. In some cases, certificates require a direct request, and the analytical laboratory is not identified in the public-facing listing. Domestic shipping runs 3 to 5 business days.
SwissChems received an FDA warning letter in December 2024, specifically citing its retatrutide and semaglutide listings as unapproved new drugs introduced into interstate commerce in violation of the Federal Food, Drug, and Cosmetic Act. That enforcement action is directly relevant to retatrutide sourcing decisions and sets SwissChems apart from the vendors ranked above it.
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Vendor Comparison
| Vendor | Retatrutide Formulations | Reported Purity | COA Access | Enforcement History |
|---|---|---|---|---|
| PureRawz | Injectable | 98%+ (MZ Biolabs) | Public, batch-specific | None on record |
| Behemoth Labz | Injectable, nasal spray | 99%+ (Colmaric Analyticals) | Public, batch-specific | None on record |
| Core Peptides | Injectable | 98%+ (third-party) | Public | None on record |
| Ascension Peptides | Injectable | 98–99% (independent) | Public, batch-specific | None on record |
| SwissChems | Injectable | 97–99% (lab not named) | On request | FDA warning letter, Dec 2024 |
Red Flags When Sourcing Retatrutide
Retatrutide’s structural complexity and research profile have attracted vendors with uneven documentation practices. Pricing significantly below market rates per vial is one signal: research-grade synthesis with proper purification and independent testing carries a cost floor that cut-rate pricing cannot accommodate without shortcutting one of those steps.
Other markers to check:
- A COA that does not name the testing laboratory
- No batch number visible on the COA or vial label
- Purity claims not backed by HPLC or mass spectrometry documentation
Retatrutide’s molecular weight of approximately 4,556 Da makes mass spec confirmation of molecular identity a required checkpoint, not optional.
Of the five vendors compared here, SwissChems is the outlier on all three counts: COA accessibility is inconsistent, the testing laboratory is not consistently named, and the company received a direct FDA enforcement action in December 2024 specifically covering its retatrutide listings.
FAQ
Does the FDA approve retatrutide?
The FDA does not approve Retatrutide (LY3437943) for any indication. It is an investigational compound in Phase 3 clinical development by Eli Lilly under the TRIUMPH program. TRIUMPH-1 topline data were reported in May 2026. All retatrutide sold by the vendors in this comparison is classified as a research chemical for laboratory use only.
What purity standard should a retatrutide COA show?
HPLC purity of 98% or higher is the accepted minimum for research-grade retatrutide. A complete COA should also include mass spectrometry confirmation of the correct molecular weight (approximately 4,556 Da) and display a batch number traceable to the specific vial. Vendor-issued or undated COAs without lab identification carry limited evidentiary value.
What formulations of retatrutide are available for research?
Injectable peptide formulations are the most widely available from domestic research vendors. Behemoth Labz additionally offers a nasal spray formulation for research designs that require a non-injectable delivery route. All formulations sold by vendors in this comparison are for laboratory research purposes only and are not approved for therapeutic use.
How does retatrutide differ from semaglutide in research contexts?
Research suggests semaglutide acts as a selective GLP-1 receptor agonist, targeting a single receptor pathway. Investigations indicate that retatrutide may serve as a model for studying simultaneous activation of the GLP-1, GIP, and glucagon receptors. The multi-receptor profile makes retatrutide a distinct research tool for studying integrated metabolic signaling pathways that single-receptor agonists cannot replicate.
Conclusion
For research-grade retatrutide with the most consistent documentation record, Purerawz and Behemoth Labz are the two strongest domestic options currently operating. PureRawz provides MZ Biolabs batch documentation and the widest catalog context for metabolic peptide research. Behemoth Labz offers Colmaric Analyticals testing, along with the added availability of a nasal spray formulation. Vendors in positions three through five are viable alternatives with shorter track records or documentation caveats.
