Both weekly incretin agonists, but retatrutide adds glucagon-receptor agonism to tirzepatide's dual GIP/GLP-1 profile. Full side-by-side reference.
The single mechanistic difference between retatrutide and tirzepatide is the addition of glucagon-receptor agonism. That third receptor is what drives the different weight-endpoint magnitude reported in Phase II research.
| Attribute | Retatrutide | Tirzepatide |
|---|---|---|
| Receptors | GIP + GLP-1 + GCG | GIP + GLP-1 |
| Half-life (published) | ~6 days | ~5 days |
| Dosing interval (research) | Weekly | Weekly |
| Weight-endpoint magnitude | Highest published | Second-highest published |
| Trial depth | Phase II | Phase III (SURPASS/SURMOUNT) |
Which is documented more
Tirzepatide has a substantially deeper published dataset — years of Phase III trials — while retatrutide is earlier in the publication cycle but carries the strongest single-endpoint magnitude reported.
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