Investigational triple GIP/GLP-1/glucagon receptor agonist (LY3437943) developed by Eli Lilly and studied in Phase 3 trials; not approved as a medicine anywhere and not for human therapeutic use.
Clinical-stageLyophilised vialAlso known as:LY3437943 · Triple Receptor Agonist · Triple G
Approximately 6 days (human; Urva et al. 2022, Phase 1b)
Storage
Lyophilised powder below −15 °C in a tightly closed container, shielded from light; equilibrate the sealed vial to room temperature before opening. Reconstituted vials 2–8 °C.
Sizes
5 mg, 10 mg
What it is
The compound. Origin, research and regulatory reality.
Retatrutide (development code LY3437943) is an investigational triple hormone-receptor agonist developed by Eli Lilly: a single synthetic peptide engineered to activate the GIP, GLP-1 and glucagon receptors. As of September 2026 it has not been approved as a medicine in any jurisdiction; Lilly states it is available only to participants in its clinical trials.
A Phase 1b multiple-ascending-dose study (Urva et al., 2022) characterised its pharmacokinetics, and a Phase 2 trial (Jastreboff et al., 2023) examined its triple-receptor mechanism and dose-dependent effect on body weight in adults with obesity. The Phase 3 TRIUMPH programme is evaluating retatrutide in obesity and related conditions.
The FDA states that retatrutide cannot be used in compounding under federal law and is not a component of any FDA-approved drug, and it has warned telehealth companies, distributors and outsourcing facilities that sold unapproved retatrutide falsely labelled ‘for research purposes’ or ‘not for human consumption’. Research-use-only vials sold commercially are outside Lilly’s clinical-trial supply chain and have not been reviewed for safety, effectiveness or quality.
Live vendor register · grouped by strength
Every vendor. Cheapest per mg first, kits listed separately.
RETATRUTIDE · price per mg
4 listings · unflagged vendors first · Listings data last updated October 2026
LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial
It is not an approved medicine anywhere and the FDA states it cannot be used in compounding under federal law. Products sold research-use-only are for laboratory research, not human use; RUO labelling does not authorise personal use.
How is research-vial retatrutide different from a pharmacy product?
There is no approved pharmacy product to compare it with: retatrutide is investigational. Lilly states it is available only to its clinical-trial participants, so any vial sold commercially sits outside that controlled chain.
What should a CoA show for retatrutide?
HPLC purity, an LC-MS mass that matches the developer-published structure (vendor pages have been seen listing wrong CAS numbers and masses for this compound), a lot number, an independent third-party lab name and a test date.