Research
Retatrutide
A synthetic peptide agonist at three receptors at once — GIP, GLP-1 and glucagon.
Available in the catalogue
Supplied as research material. Sizes and pricing are on the product page. Availability is not a statement about what a compound does.
What is being investigated
Directions the published work points at, and how far each has actually got. These are open questions, not established effects: most of what looks promising in cells does not replicate in animals, and most of what works in animals does not work in people. Nothing here is a claim about what this compound does for anyone.
- Body weight in obesity
Phase 2 reported placebo-adjusted mean reduction of roughly 16% at 24 weeks and 22% at 48 weeks. Phase 2 is where most of what looks decisive stops looking decisive, and the phase 3 programme has not reported.
Human trials
- Liver fat
Hepatic fat content was measured in the phase 2 work, on the question of whether adding glucagon receptor agonism reaches the liver in a way the other incretins do not.
Human trials
- What the glucagon receptor adds
The design question, and the one the trials so far cannot answer: glucagon receptor activation raises energy expenditure, a different lever from appetite and insulin, but no published trial separates the three receptors' contributions.
Proposed from mechanism
- Long-term safety
Unlike semaglutide and tirzepatide this compound has no authorisation anywhere and no long-term human data at all. It is the newest molecule here and the least is known about it.
Proposed from mechanism
Published research
Every reference below was checked against the published record before being listed, with the model each study used.
- Jastreboff et al. (2023)New England Journal of Medicine · 389(6):514–26
Reported placebo-adjusted mean weight reduction of roughly 16% at 24 weeks and 22% at 48 weeks in adults with obesity.
human, randomised double-blind placebo-controlled phase 2 Source
Further reading
Longer articles on handling, analysis and what the published work reports.
- Retatrutide (LY3437943): what the research says
A triple hormone receptor agonist still in development, with no marketing authorisation anywhere. What the published phase 2 work reported, and what it did not.
- How to store research peptides
Lyophilised peptides at -20°C, reconstituted at 2–8°C, ambient in transit. Why the dry cake tolerates shipping, and what actually degrades a vial.
- Peptide shelf life and stability
How long lyophilised and reconstituted peptides keep, and the four things that shorten it: temperature, moisture, light and oxidation. Storage figures included.
- How to reconstitute lyophilised peptides
How to reconstitute a lyophilised peptide with bacteriostatic water without damaging it: why you run the liquid down the vial wall and never shake it.