Retatrutide Research
Retatrutide Clinical Trial Timeline: Phase 1 to TRIUMPH
Retatrutide's clinical timeline began with Phase 1 first-in-human dosing around 2020, followed by Phase 2 trials in obesity and type 2 diabetes with results published in NEJM in 2023. The Phase 3 TRIUMPH programme launched in 2023 and continues to read out across 2025–2026.
Key facts
- Phase 1
- ~2020 (NCT04143802)
- Phase 2
- Published NEJM 2023
- Phase 3
- TRIUMPH programme, 2023–ongoing
What is the TRIUMPH programme?
TRIUMPH is Eli Lilly's Phase 3 clinical development umbrella for retatrutide, comprising multiple trials across obesity, type 2 diabetes, and related metabolic indications. Registrations are listed on ClinicalTrials.gov.
Quick reference
| Phase | Year | Notes |
|---|---|---|
| Phase 1 | 2020 | First-in-human, single/multiple ascending doses |
| Phase 2 | 2022–2023 | Obesity + T2D populations; NEJM publication |
| Phase 3 | 2023–2026 | TRIUMPH programme, multiple indications |
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 — 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?
Frequently asked questions
- How long are Phase 3 trials?
- TRIUMPH trials run multi-year, with primary endpoints typically at 48–68 weeks.
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.
- TrialClinicalTrials.gov — retatrutideclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-1 (NCT05869903) — Retatrutide Phase 3 obesity trialclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-2 (NCT05882045) — Retatrutide in obesity + T2DMclinicaltrials.gov
- TrialClinicalTrials.gov · TRIUMPH-3 (NCT05936151) — Retatrutide + established CVDclinicaltrials.gov
- PubMedJastreboff et al., Triple-Hormone-Receptor Agonist Retatrutide for Obesity — NEJM 2023 (PMID 37356472)pubmed.ncbi.nlm.nih.gov
- PubMedRosenstock et al., Retatrutide in adults with T2D — Lancet 2023 (PMID 37356473)pubmed.ncbi.nlm.nih.gov
- PubChemPubChem · Retatrutide (CID 156588324)pubchem.ncbi.nlm.nih.gov
- DrugBankDrugBank · Retatrutide (DB18435)go.drugbank.com
- GuidelineGoogle — Creating helpful, reliable, people-first contentdevelopers.google.com
Written and reviewed by
Jack Muncaster · Founder, UK Peptides
Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He 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.
More Retatrutide Research articles
- Who Makes Retatrutide? Eli Lilly and DevelopmentRetatrutide is developed by Eli Lilly and Company under the internal code LY3437943, following tirzepatide as their next-generation incretin peptide.
- Retatrutide Half-Life and Pharmacokinetics (Research Data)Retatrutide half-life is approximately 6 days, supporting once-weekly research administration. Pharmacokinetics from published Phase 1 trial data.
- Retatrutide CAS Number and Chemical IdentityRetatrutide CAS number, PubChem CID, molecular formula and chemical identifiers. Reference chemistry data for the LY3437943 investigational peptide.
- How Retatrutide Differs From First-Generation IncretinsRetatrutide differs from first-generation incretins (exenatide, liraglutide) by activating three receptors and using albumin binding for a longer half-life.
- Retatrutide Storage and Stability (Research Handling)Retatrutide storage: lyophilised vials stable at 2–8°C, reconstituted material for short-term refrigerated use. Handling guidance for research settings.
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