Retatrutide (GLP-3 RT) is available from US research peptide suppliers under research-use-only labeling. It is not a controlled substance, not FDA approved, and not subject to the compounding pharmacy framework. The single most important variable in sourcing it is COA quality — specifically, whether the supplier uses independent third-party mass spectrometry to confirm molecular identity, not just HPLC purity. Because no FDA reference standard exists for retatrutide, identity verification matters more here than for any other peptide in the incretin class.
Evo Peptides carries GLP-3 RT in 15mg, 20mg, and 30mg formats with independently verified HPLC purity of 99.27%, 99.85%, and 99.91% respectively — batch-specific third-party COA included, same-day shipping before 3:00 PM CST from Wisconsin, and full credit/debit card processing via Bankful.
Research Use Only (RUO). Not for human consumption. These statements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Must be 21+ to purchase.
Retatrutide is an investigational compound — currently in Phase 3 clinical trials under the designation LY3437943 by Eli Lilly — and is not FDA approved for any therapeutic indication. It is also not a scheduled substance and does not appear on any federal controlled substance list. US research peptide vendors can legally sell it under research-use-only (RUO) labeling for in vitro laboratory work.
Critically, retatrutide's legal status is entirely separate from the FDA compounding pharmacy framework. The 2023 compounding restrictions and the ongoing PCAC review process govern which bulk drug substances licensed compounding pharmacies may use to fill prescriptions. That framework does not regulate research peptide vendors operating under RUO labeling. Retatrutide has been continuously available through the RUO channel regardless of developments in compounding law — and will remain so unless it achieves FDA approval or is scheduled, neither of which is imminent.
Researchers purchasing for legitimate in vitro or preclinical animal studies are operating within the established legal framework. Misuse — purchasing for human administration — is outside that framework and illegal regardless of what a vendor's website says. For context on how PCAC developments affect related compounds, see the BPC-157 FDA status 2026 guide.
RUO labeling designates the product for in vitro laboratory research, not for human or veterinary use. It is a legal use-designation, not a loophole. Vendors operate under this classification; buyers acknowledge research-only intent at purchase. The RUO channel is distinct from the prescription compounding channel and is governed differently.
Most peptides in the research catalog have been available long enough that the market has self-selected — vendors who produce poor-quality material don't survive sustained scrutiny from researchers running proper controls. Retatrutide is different for three compounding reasons.
First, it is a relatively new synthesis target for research vendors. The surge in interest following Phase 2 trial results attracted vendors who had not previously attempted to synthesize lipidated triple agonist peptides. Synthesizing a 39-residue lipidated peptide with balanced agonism at three distinct receptors is substantially harder than synthesizing a 28-residue single agonist. Synthesis errors produce compounds with high HPLC purity but wrong sequence or missing lipid modification — failures that pass a purity test but produce nothing in a functional assay.
Second, no pharmacopeial reference standard exists for retatrutide. Tirzepatide is FDA approved, so independent labs can use an official reference standard to anchor identity confirmation. For retatrutide, there is no such standard. Mass spectrometry of the amino acid sequence is definitive, but a vendor who only runs HPLC without MS identity confirmation leaves a gap that could hide a substitute compound entirely. A researcher running a tirzepatide-comparison study with mislabeled or de-lipidated retatrutide will not produce clean data — and may not know why for months. See the peptide purity guide for a full breakdown of what each test actually measures.
Third, it is the highest-priced peptide in most research catalogs, which creates direct economic pressure on vendors to cut corners on analytical costs while maintaining price points that look competitive.
A Certificate of Analysis is the only document that tells you what is actually in the vial. For most research peptides, HPLC purity is a reasonable first filter. For retatrutide, it is not enough on its own. The absence of a reference standard means HPLC tells you only that something pure is present — not that it is retatrutide. For full guidance on reading any peptide COA, see how to read a peptide COA. Here is what a sufficient GLP-3 RT COA must include, and what is not good enough.
The numbers below are not floor claims. They are the actual HPLC purity values from independent third-party COAs, specific to each production variant currently in stock. The COA for each variant is accessible on the product page and at evopeptidesus.com/coas before purchase.
At 95% purity, up to 5% of a lipidated triple agonist sample is uncharacterized impurities — most likely truncation sequences and de-lipidated variants with partial or absent receptor activity. These shift dose-response curves, increase inter-experiment variability, and make it harder to isolate the glucagon receptor contribution specifically. At 99.91%, the contamination floor is under 0.1%. For comparative incretin study designs where the glucagon receptor axis is the primary variable, this difference is not cosmetic.
The following patterns indicate a vendor unlikely to meet the analytical standards required for reproducible GLP-3 RT research. Any one of them warrants scrutiny before purchase.
If you are sourcing both GLP-3 RT (retatrutide) and GLP-2 TRZ (tirzepatide) for a parallel research design, the COA bar is identical for both. The underlying verification challenge is different. See the tirzepatide vs retatrutide research comparison for head-to-head study design guidance.
| Factor | GLP-2 TRZ — Tirzepatide | GLP-3 RT — Retatrutide |
|---|---|---|
| FDA approval status | Approved | Investigational |
| Pharmacopeial reference standard | Exists | Does not exist |
| MS identity confirmation | Important | Non-negotiable |
| Receptor targets | GLP-1 + GIP (dual) | GLP-1 + GIP + Glucagon (triple) |
| Market maturity | High — many tested vendors | Lower — newer synthesis target |
| Typical market price | $60–$90 / vial | $85–$130 / vial |
| Minimum HPLC purity | ≥99% for both — no exceptions | |
| Evo Peptides actual COA purity | View on product page | 99.27% / 99.85% / 99.91% by variant |
| Source at Evo Peptides | Shop GLP-2 TRZ › | Shop GLP-3 RT › |
Lipidated peptides require more care than standard research peptides. The C18 fatty acid modification that provides extended in vivo half-life also makes the compound more susceptible to aggregation under suboptimal reconstitution conditions. The following protocols apply to lyophilized GLP-3 RT as supplied by Evo Peptides. For complete handling protocols across all peptide classes, see the peptide storage and reconstitution guide. Bacteriostatic water (10ml) is available alongside GLP-3 RT for complete reconstitution kits.
Each freeze-thaw cycle after reconstitution degrades the compound. Aliquot into volumes sufficient for one experimental session before freezing. Once thawed, do not refreeze. Snap-freeze aliquots in liquid nitrogen if −80°C long-term storage is intended.
Understanding the research landscape for GLP-3 RT clarifies which analytical requirements are most critical for a given protocol. The compound is studied across several distinct mechanistic questions, each with different endpoint requirements. See the GLP-3 RT research guide for the full mechanism profile with cited Phase 2 data.
The glucagon receptor component is the defining feature of GLP-3 RT relative to dual agonists. In preclinical rodent models, glucagon receptor agonism is associated with increased energy expenditure beyond what GLP-1 agonism produces alone — mediated through brown adipose tissue thermogenesis (UCP-1 upregulation) and increased hepatic glucose oxidation. This is the primary territory where GLP-3 RT differs measurably from GLP-2 TRZ in head-to-head designs. Lipidation confirmation in the COA is especially critical for energy expenditure endpoints — de-lipidated material has different pharmacokinetics and will produce artificially attenuated thermogenic readings.
Triple incretin agonism studies in diet-induced obesity (DIO) models examine fat mass reduction alongside lean mass preservation — a key pharmacological question distinguishing the drug class. Research designs comparing GLP-3 RT against GLP-2 TRZ allow direct attribution of lean mass effects to the glucagon receptor axis. Sourcing both compounds from the same vendor in the same batch window ensures consistent analytical methodology across study arms — a common confound in multi-compound incretin studies.
Glucagon receptor activation has established roles in hepatic gluconeogenesis and emerging roles in hepatic lipid clearance. GLP-3 RT studies in NASH and NAFLD preclinical models represent a significant portion of the published research base. Liver triglyceride quantification and histological endpoints (NAFLD activity score, fibrosis staging) are the primary readouts. Lipidation confirmation is particularly relevant here because de-lipidated material with altered pharmacokinetics will produce different hepatic exposure profiles than the intact compound.
Head-to-head designs comparing GLP-3 RT against GLP-2 TRZ (tirzepatide) in the same model system allow direct attribution of pharmacological effects to the glucagon receptor contribution. Evo Peptides carries both compounds for parallel study design. For detailed mechanistic comparison and study design considerations, see tirzepatide vs retatrutide: research comparison.
Evo Peptides carries GLP-3 RT (retatrutide) in three variants — 15mg, 20mg, and 30mg — with independent third-party HPLC and mass spectrometry verification on every batch. The COA is accessible on the product page before purchase. Same-day shipping on orders placed before 3:00 PM CST, fulfilled from Wisconsin. Credit and debit cards processed via Bankful; cryptocurrency also accepted.
Orders placed before 3:00 PM CST ship the same business day from Wisconsin. All 50 states. Credit card, debit card, and cryptocurrency accepted via Bankful. Free shipping on orders over $200.
Yes. Retatrutide is not a scheduled or controlled substance. US research peptide vendors can legally sell it under RUO labeling for in vitro laboratory work. It is not FDA approved and may not be purchased for human consumption. The FDA compounding pharmacy framework — including the ongoing PCAC review process — does not govern RUO research vendors and does not affect retatrutide availability through this channel.
At minimum: HPLC purity at 99%+ with chromatogram available on request; mass spectrometry identity confirmation (ESI-MS or MALDI-TOF confirming MW ~4,900 Da); the independent testing laboratory name; a batch/lot number matching the vial; and an issue date within 12 months. A COA without MS identity confirmation is insufficient for retatrutide. See the COA evaluation guide for full detail.
Tirzepatide is FDA approved, so a pharmacopeial reference standard exists that independent labs can use to anchor identity confirmation. Retatrutide has no such standard. Mass spectrometry confirmation of the amino acid sequence is the only reliable identity test — HPLC alone cannot confirm identity without a reference compound. This is why a purity-only COA is insufficient for GLP-3 RT in a way it is not for tirzepatide.
GLP-3 RT is the research catalog designation for retatrutide (LY3437943), a triple GLP-1/GIP/glucagon receptor agonist in Phase 3 development by Eli Lilly. GLP-2 TRZ (tirzepatide) is a dual GLP-1/GIP agonist — FDA approved. The glucagon receptor component of GLP-3 RT drives additional energy expenditure effects not present with tirzepatide alone. They are chemically distinct compounds with different sequences, molecular weights, and lipid modifications. See the GLP-3 RT research guide for the full mechanistic profile.
Store lyophilized GLP-3 RT at −20°C, protected from light and moisture. Reconstitute with bacteriostatic water or 0.1–1% sterile acetic acid — add solvent slowly, swirl gently, do not vortex. After reconstitution, store at 4°C and use within 14 days. For longer storage, aliquot into single-use volumes and store at −80°C. Do not freeze-thaw reconstituted peptide. See the peptide storage guide for full protocols.
Yes — and for parallel designs comparing dual vs triple receptor agonism, sourcing both from the same vendor in the same batch window is methodologically preferable. It ensures consistent COA methodology and analytical standards across all study arms. Evo Peptides carries both GLP-3 RT and GLP-2 TRZ with the same third-party COA standards applied to both.
COA-verified GLP-3 RT from a US supplier with independent testing typically ranges $85–$130 per vial. Evo Peptides carries it at $89.95/vial with free shipping on orders over $200 and same-day shipping before 3:00 PM CST from Wisconsin. Pricing significantly below $80 per vial warrants direct scrutiny of the COA methodology before purchase.