The receptor everyone had discounted
GIP is the other incretin hormone, released from the gut alongside GLP-1. For a long stretch the prevailing reading was that GIP agonism would be unhelpful or actively counterproductive for metabolic work, and several programmes went the opposite way and pursued GIP blockade.
Tirzepatide combined GIP and GLP-1 agonism in one molecule and outperformed GLP-1 agonism alone in head-to-head trials. That result forced a genuine rethink of what the GIP receptor contributes.
GIP itself is released from cells in the upper small intestine when food arrives, and it was characterised well before its better-known counterpart. Early metabolic work on it was discouraging enough that most of the field moved on, which is a large part of why the head-to-head result landed as hard as it did when it came.
Why one molecule beats two injections
Two receptors could in principle be reached with two separate compounds. Building both activities into one sequence fixes the ratio between them at manufacture, so every dose delivers the same balance and the pharmacokinetics of the two arms cannot drift apart.
It also makes the ratio itself a design decision. Tirzepatide is not balanced equally between its two targets, and where that balance sits is treated as a defining property of the molecule.
The sequence started from the GIP side rather than the other one, with modifications that open up activity at both receptors and a fatty acid chain for albumin binding. That lineage is worth carrying into any comparison you read: the molecule is nearer to a reworked GIP peptide that also engages the GLP-1 receptor than to a GLP-1 analogue with a second activity bolted on.
| Class | Dual receptor agonist |
| Receptors | GIP and GLP-1 |
| Notable for | Vindicating GIP agonism as a target |
| Trial programme | SURPASS and SURMOUNT |
| Stocked here | No, reference page |
| Related products | Semaglutide, retatrutide |
| Evidence base | Completed phase 3 programme |
| Category | Research use only |
Reference data for the material in the vial. No outcome is implied.
A finished clinical programme
The SURPASS and SURMOUNT trials covered glycaemic control and weight respectively, at a scale and duration that puts tirzepatide in a small group within this catalogue: compounds with a completed phase 3 record rather than a promising early one.
We do not currently stock tirzepatide. It is documented here because you cannot read the retatrutide and semaglutide pages sensibly without it, and leaving a gap in the middle of the class would make those comparisons worse.
If a comparison page sent you here looking for what is tirzepatide, the short version is a dual GIP and GLP-1 agonist with a completed phase 3 record and an approval behind it. We do not supply it. Saying so on the page is easier than explaining afterwards why the semaglutide file and the weight research area keep pointing at a compound the catalogue does not carry.
Why a compound we do not sell has a file here
Documenting a product you cannot ship is unusual, and the reason is plain enough: a knowledge base with a hole in the middle of a class produces worse decisions than one without. Anyone weighing three molecules needs all three described to the same standard, or the comparison quietly turns into an argument for whatever happens to be in stock. The indexed literature on PubMed is where that same-standard reading has to begin.
It also draws a boundary we would rather state than imply. Everything in this catalogue is supplied under the research use only classification, and an approved medicine is a different kind of object altogether: a licensed product, a defined indication, an assessment on file. The European public assessment report for the authorised product is the document that distinction actually lives in.
Tirzepatide in the catalogue
HPLC-confirmed at 99% or better; the batch certificate is available on request.
Where Tirzepatide fits in
The context around this compound, in three pages.
About Tirzepatide
Common questions, answered directly.