Retatrutide — the triple agonist.
GLP-1 + GIP + glucagon receptor agonism simultaneously. Retatrutide is the most potent weight-loss compound currently tracked on PeptideCompare — and consistently one of the best-priced in our EU database.
- Triple agonist (GLP-1 · GIP · glucagon) developed by Eli Lilly; no drug of this class is approved anywhere yet.
- Phase 2 trial reported up to 24.2% mean body-weight reduction at 48 weeks at the highest dose — the largest published GLP-1-class result to date.
- Phase 3 TRIUMPH programme is ongoing through 2026; long-term safety and cardiovascular outcomes are not yet established.
- The glucagon component adds a more complex side-effect profile (nausea, vomiting, possible hepatic effects) than pure GLP-1 drugs.
- Research compound only — purity verification is critical for a complex 39-amino-acid peptide.
What is Retatrutide?
Retatrutide (LY3437943) is a once-weekly injectable peptide developed by Eli Lilly that acts simultaneously as a GLP-1 receptor agonist, GIP receptor agonist, and glucagon receptor agonist — hence "triple agonist." No approved drug of this class yet exists. It is currently in Phase 3 clinical trials after remarkable Phase 2 results showing up to 24% body weight reduction at 48 weeks — higher than any previously published GLP-1 class result.
It is available from EU research vendors strictly for laboratory research purposes. It is the most-compared peptide on PeptideCompare by price per mg.
What does the research show?
What to look for when buying in Europe
Retatrutide is a complex 39-amino acid peptide — synthesis difficulty is high and purity verification is critical. Impure batches are a real risk at this compound's price point. Minimum acceptable purity: ≥98% by HPLC with mass-spec identity confirmation. Any EU vendor without a batch-specific COA from a named third-party lab should be avoided.
Molecular information
Pharmacokinetics
Compare Retatrutide prices across EU suppliers
14 EU vendors · COA-verified · 10mg / 20mg / 30mg · Updated monthly
Frequently asked questions
What is retatrutide? ▾
Retatrutide (LY3437943) is an investigational once-weekly injectable peptide developed by Eli Lilly that activates three receptors simultaneously — GLP-1, GIP and glucagon. It is studied for weight management and metabolic conditions but is not an approved medicine in any country.
Is retatrutide approved in the EU? ▾
No. Retatrutide is in Phase 3 clinical trials and is not authorised by the EMA, FDA or any other regulator. EU research vendors sell it strictly for laboratory research, not for human use.
How much weight loss did retatrutide show in trials? ▾
The Phase 2 obesity trial published in the New England Journal of Medicine reported a mean body-weight reduction of up to roughly 24% at 48 weeks at the highest dose — dose-dependent and larger than previously published GLP-1-class results. These are trial figures, not a guarantee of individual outcomes.
How is retatrutide different from semaglutide or tirzepatide? ▾
Semaglutide targets one receptor (GLP-1) and tirzepatide targets two (GLP-1 + GIP). Retatrutide adds a third — the glucagon receptor. The extra glucagon activity is associated with greater weight effects in trials but also a more complex side-effect profile.
What are the known side effects? ▾
In trials the most common adverse events were gastrointestinal — nausea, vomiting and diarrhoea — mostly mild to moderate and concentrated during dose escalation. The glucagon component may add effects not seen with pure GLP-1 drugs. Long-term safety is still being studied in Phase 3.
Why does purity matter so much for retatrutide? ▾
Retatrutide is a complex 39-amino-acid peptide that is difficult to synthesise. Impure or mislabelled batches are a real risk at this price point, so a batch-specific certificate of analysis (COA) showing ≥98% HPLC purity from a named third-party lab is essential.
What should a COA for retatrutide show? ▾
A meaningful COA states the specific batch, an HPLC purity figure (ideally ≥98%), mass-spec identity confirmation, and the name of the testing lab. A generic or undated certificate that does not match the batch is a red flag.
When are Phase 3 results expected? ▾
The Phase 3 TRIUMPH programme is ongoing as of 2026. Until those trials read out and a regulator reviews them, retatrutide remains investigational.
Is retatrutide banned in sport? ▾
Yes. As a metabolic/hormonal agent it falls under prohibited substances on the WADA list. Athletes subject to anti-doping rules should treat it as prohibited.
How is retatrutide priced across EU suppliers? ▾
PeptideCompare tracks retatrutide across EU vendors in multiple vial sizes. Because synthesis is difficult, price per mg varies considerably between suppliers for equivalent verified purity — which is exactly what the comparison table is for.
References
- Phase 2, double-blind, randomised, placebo-controlled obesity trial reporting dose-dependent weight reduction up to ~24% at 48 weeks. Jastreboff AM, et al. N Engl J Med. 2023;389(6):514–526. DOI PubMed 37366315
- Phase 2 trial in adults with type 2 diabetes establishing the GLP-1/GIP/glucagon agonist profile and glycaemic effects. Rosenstock J, et al. Lancet. 2023;402(10401):529–544. DOI PubMed 37385280
- Design rationale for the registrational Phase 3 TRIUMPH trials in obesity, OSA and knee osteoarthritis. Giblin JT, et al. Diabetes Obes Metab. 2026. DOI