The short answer
Retatrutide is the INN, LY3437943 the development code, and reta an informal abbreviation. The codes most easily confused with it are Lilly's own: LY3298176 is tirzepatide and LY3502970 is orforglipron.
Key facts
- INN
- Retatrutide
- Development code
- LY3437943
- Informal
- Reta
- Easily confused
- LY3298176: tirzepatide
- Also confusable
- LY3502970: orforglipron
- Finds research
- Retatrutide, LY3437943
- Finds market content
- Reta
The three names and what each returns
Retatrutide finds the peer-reviewed literature and the trial registrations. LY3437943 finds the same plus earlier development-era records, including the Coskun discovery paper's title. Reta finds forum and commercial content almost exclusively, because no researcher uses it.
The confusion that actually causes errors
Not spelling, but the Lilly codes. LY3437943, LY3298176 and LY3502970 are retatrutide, tirzepatide and orforglipron respectively. Three similar codes, one company, three compounds at different regulatory stages. This library found two real errors from exactly this: a tirzepatide PubChem record cited as retatrutide, and orforglipron's ATTAIN-1 trial labelled as retatrutide's TRIUMPH-1.
Research material referenced
Retatrutide 10mg, third-party HPLC tested
Why the trial names are also confusable
TRIUMPH is retatrutide's Phase 3 programme; SURMOUNT is tirzepatide's; ACHIEVE and ATTAIN are orforglipron's. All are Lilly programmes with similar naming conventions running concurrently. Checking which compound a registration names, rather than trusting the programme name, is the only reliable approach.
Hyphenation and case
LY3437943, LY-3437943 and LY 3437943 all appear and signal nothing. Retatrutide is not hyphenated. None of these variations carries information about the compound.
The practical rule
Verify the compound named in any record before citing it. A number that looks right is not evidence that it is right. Both of this library's errors involved identifiers that appeared entirely plausible, from the correct company, in the correct format, pointing at the wrong molecule.
Quick reference
| Code | Compound | Status |
|---|---|---|
| LY3437943 | Retatrutide | Investigational |
| LY3298176 | Tirzepatide | Approved |
| LY3502970 | Orforglipron | Approved (UK, Aug 2026) |
Frequently asked questions
- Is 'reta' used in research?
- No. It appears in commercial and forum content. Papers use retatrutide or LY3437943.
- What is the most common source of confusion?
- Lilly's three similar development codes: LY3437943, LY3298176 and LY3502970 are three different compounds at three different regulatory stages.
- How do I avoid citing the wrong one?
- Check the compound named in the record itself. A plausible-looking identifier from the right company can still point at the wrong molecule.
Extended research context
The Retatrutide Research deep dive
Deep dive: how the triple-agonist scaffold was engineered
Retatrutide's 39-residue backbone was designed by Eli Lilly's peptide chemistry team to preserve the pharmacophores of three glucagon-family receptors on a single chain. The N-terminal domain retains GIP-receptor contacts, mid-chain substitutions restore GLP-1-receptor affinity lost in native GIP, and additional residue swaps confer glucagon-receptor engagement. A γGlu-2xOEG linker anchors a C20 fatty diacid at Lys17, which reversibly binds serum albumin and slows renal clearance. This is the same albumin-tethering strategy Novo Nordisk pioneered with semaglutide and Lilly refined further in tirzepatide.
The TRIUMPH Phase 3 programme in context
TRIUMPH is Lilly's global Phase 3 development umbrella for retatrutide, spanning obesity (TRIUMPH-1 through TRIUMPH-4), type 2 diabetes, MASH (metabolic dysfunction-associated steatohepatitis), and knee osteoarthritis linked to obesity. Readouts began in 2025 and continue through 2026. Because the compound is investigational, no regulator (FDA, EMA, or MHRA) has issued marketing authorisation, and legitimate supply exists only for laboratory reference and research contexts, never for human administration.
How retatrutide differs from tirzepatide and semaglutide at the mechanism level
Semaglutide is a mono-agonist (GLP-1 only). Tirzepatide is a dual agonist (GIP + GLP-1). Retatrutide adds glucagon-receptor activity, which pre-clinical and Phase 2 data suggest contributes to energy expenditure in addition to appetite regulation and glucose-dependent insulin release. This three-receptor combination is why retatrutide is sometimes called a 'metabolic multi-tool' peptide in the trade press, but the pharmacology is more nuanced than the label implies.
Research applications
- ▸In vitro receptor-binding assays across GIP-R, GLP-1R and GCGR panels
- ▸Comparator studies alongside semaglutide, tirzepatide and liraglutide reference standards
- ▸Analytical-method development: HPLC retention profiling and LC-MS confirmation
- ▸Stability testing of lipidated 39-residue peptides in aqueous and lyophilised forms
- ▸Reference material for teaching incretin pharmacology in university-level courses
Handling checklist
- ✓Store lyophilised vials at −20 °C; protect from light and humidity
- ✓Reconstitute with bacteriostatic water; avoid vortexing (foams the peptide)
- ✓Once reconstituted, store at 2–8 °C and use within 28 days
- ✓Verify batch CoA: HPLC ≥98%, mass matches ~4,731 Da, endotoxin low
- ✓Do not administer to humans or animals. Research use only
Common research-handling mistakes
Learnt from thousands of researcher orders across our UK labs.
✗ Confusing retatrutide with tirzepatide in supplier catalogues
Fix: Cross-check the LY code (LY3437943 = retatrutide; LY3298176 = tirzepatide) and the receptor profile on the CoA.
✗ Using tap or filtered water for reconstitution
Fix: Only use bacteriostatic water for injection (0.9% benzyl alcohol) or sterile water, never lab DI water.
✗ Storing reconstituted solution at room temperature
Fix: Refrigerate at 2–8 °C immediately after reconstitution; discard after 28 days.
Continue researching
Peer-reviewed guides, comparators and matched reference materials.
Related questions researchers ask
- Is retatrutide the same molecule as LY3437943?
- What is the correct spelling: retatrutide or retatrutid?
- Is retatrutide a GLP-1 drug?
- Which company makes retatrutide?
- When will retatrutide be FDA approved?
- Is retatrutide legal in the UK?
Primary sources & clinical trials
Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.
- PubMedCoskun T et al., LY3437943. Cell Metab 2022 (PMID 35985340)pubmed.ncbi.nlm.nih.gov
- PubChemPubChem · Tirzepatide, LY3298176 (CID 166567236)pubchem.ncbi.nlm.nih.gov
- TrialClinicalTrials.gov: ATTAIN-1, orforglipron (NCT05869903)clinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-1 (NCT05929066). Retatrutide Phase 3 obesity trialclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-2 (NCT05929079). Retatrutide in type 2 diabetesclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-3 (NCT05882045). Retatrutide + established CVDclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-4 (NCT05931367). Retatrutide once weeklyclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-5 (NCT06662383). Retatrutide vs tirzepatideclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-6 (NCT06859268). Maintenance of weight reductionclinicaltrials.gov
- PubMedJastreboff AM et al., Triple-Hormone-Receptor Agonist Retatrutide for Obesity. NEJM 2023 (PMID 37366315)pubmed.ncbi.nlm.nih.gov
- PubMedRosenstock J et al., Retatrutide for people with type 2 diabetes. Lancet 2023 (PMID 37385280)pubmed.ncbi.nlm.nih.gov
- DrugBankDrugBank · Retatrutide (DB18435)go.drugbank.com
Written and reviewed by
The UK Peptides Editorial Team · Research library, UK Peptides
The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.
More Retatrutide Research articles
- The History of RetatrutideFrom the 2022 Cell Metabolism discovery paper through Phase 2 in NEJM to the TRIUMPH Phase 3 readouts of 2026 and a signalled FDA filing.
- Retatrutide Clinical Trial Timeline: Phase 1 to TRIUMPHRetatrutide trial timeline: Phase 1 in 2020, Phase 2 in NEJM 2023, Phase 3 TRIUMPH readouts December 2025 to July 2026, FDA filing signalled for Q1 2027.
- Who Develops Retatrutide?Eli Lilly, under the code LY3437943. Why that matters for reading trial data, and why no licensed retatrutide product exists.
- Retatrutide Half-Life: Where It Comes FromThe C20 diacid binds albumin reversibly, supporting once-weekly trial dosing. Why chain length sets duration across the whole incretin family.
- Retatrutide Chemical Identity: What Can Actually Be VerifiedRetatrutide has no findable PubChem record. What that means for its reported CAS and molecular weight, and why one widely cited identifier is tirzepatide's.
Popular across the research hub
One flagship guide from every other research category.
- GHK-Cu (Copper Peptide)What Separates One Copper Peptide Brand From Another
- TB-500 (Thymosin β4 fragment)BPC-157 and TB-500 Together: What the Evidence Says
- BPC-157 (Pentadecapeptide)The Stability Claim, Examined
- CJC-1295 & IpamorelinWhat the Published Literature Contains
- Peptide ReferencePeptides: A Complete Reference Guide
- Bacteriostatic WaterWhich Diluent, and What the Choice Actually Trades
- Research & Regulatory NewsTRIUMPH-6: Maintenance of Weight Reduction
- GLP-1 & Incretin ScienceComparing Things That Were Never Compared
- MOTS-c (Mitochondrial Peptide)A Class, Not a Compound
- Semax (ACTH Fragment Peptide)A Mechanism Layer Below Gene Expression
- Selank (Tuftsin Analogue)Why Proline Keeps Appearing in These Sequences
- DSIP (Delta Sleep-Inducing Peptide)An Antibody Reports What It Binds, Not What Is There
- KLOW (Blend)Equal Milligrams Is Not Equal Molecules
- GLOW (Blend)Synergy Is a Measurable Claim, Not an Assumption
- MT-2 (Melanotan II)Melanotan 2 Nasal Spray and Why the Dose Is Unknowable
- IGF-1 LR3A Natural Experiment in Absent IGF-1
- GlutathioneGlutathione Proposed as a Carrier, Not Just a Buffer
- NAD+Eighty Daltons Apart, and Metabolically Opposed
- KPVThe Transporter That Explains the Tripeptide