Trial review

Retatrutide Phase 3 Results and How It Compares

What is citable

The phase 2 trial, published in the New England Journal of Medicine in 2023 (DOI 10.1056/NEJMoa2301972). That is a real primary source and it is the strongest thing available for this compound.

Retatrutide adds glucagon receptor agonism to the GLP-1 and GIP mechanisms tirzepatide already combines. The rationale is that glucagon receptor activation raises energy expenditure and shifts hepatic lipid metabolism on top of the appetite and glycaemic effects of the other two.

The phase 3 programme is TRIUMPH. It is running.

Why no phase 3 number appears here

Searches return specific figures with confident framing. When we traced them, the sources were overwhelmingly commercial — including at least one vendor selling research peptides, and sites carrying provider advertising inside clinical copy.

We could not locate the figure in a peer-reviewed publication or a registry results posting. Under our evidence policy that makes it unverified, and unverified clinical figures do not publish here regardless of how many places repeat them.

Worth stating plainly: this costs us search position on the highest-demand query in this category. A number would rank better than an explanation. That is the price of the standard, and a publication that abandoned it here would have no basis for the corrections it publishes elsewhere.

Phase 2 is not a preview of phase 3

Phase 2 trials are designed for dose ranging and preliminary efficacy. Phase 3 enrols broader populations and applies more conservative analyses, and results in this field routinely move downward between the two.

Treating a phase 2 figure as a prediction is a recognised error. Treating an unverified phase 3 figure as established is a larger one.

Why this compound attracts a grey market

Three conditions coincide: enormous search interest, no approved product and therefore no lawful supply or price anchor, and availability to laboratories as a research chemical.

The result is an unapproved drug sold to consumers under "research use only" labelling — which is a complete answer about what it is. No prescriber, no licensed pharmacy, no verifiable testing, no recourse. That is not a cheaper version of compounded medicine; compounding at least happens inside the regulatory system.

Four questions for any retatrutide figure you encounter

1. What is the source, and can you open it?
2. Does that source sell peptides or carry provider advertising?
3. Does the figure name an estimand? Trials publish more than one.
4. Does it name the dose and duration? A percentage without them is not a result.

What would change this page

A TRIUMPH publication in a peer-reviewed journal, or results posted to the registry. We check on our normal review cycle, and this page updates when there is something to update it with.

Questions readers actually ask

Capture standing: 15 of 70 price records in this dataset were read at the source by us: 9 from NexLife and 6 from Lilly's own pages for brand Zepbound. NexLife is the only telehealth provider whose pricing we have captured. Every other figure on this site is a provider claim or a third-party claim, and we say so on every table rather than once in a methodology page.