Tirzepatide — reference

Tirzepatide: dual gip and glp-1 receptor agonist, approximate mass 4813.5 Da, 5 days half-life. Identity, evidence base, analytical considerations and limitations.

Scope

A maintained identity and evidence reference for Tirzepatide. It is deliberately narrow: what the molecule is, what has been published about it, and what an analytical report on it can and cannot establish. It contains no dosing recommendations and is not advice about anyone's care.

Where a figure is approximate this page says so. Where something is unknown, it says that instead of filling the gap.

Identity

Masses quoted here are approximate and are given for orientation when reading an analytical report. For a mass-error calculation, use the exact monoisotopic mass computed from the elemental composition rather than a rounded figure from a reference page, including this one.

What it is

Tirzepatide is a single 39-residue peptide with a C20 fatty diacid moiety, engineered to agonise both the GIP and the GLP-1 receptor. It is not a co-formulation of two drugs, which is a distinction that gets lost regularly in discussion here.

How much of its effect is attributable to GIP agonism as opposed to simply achieving greater receptor engagement remains genuinely unsettled. The mechanistic literature is active and the honest position is that the question is open.

Evidence base

Published studies and programmes most relevant to this compound:

• SURPASS-1
• SURPASS-2
• SURPASS-3
• SURPASS-4
• SURMOUNT-1
• SURMOUNT-2
• SURMOUNT-3
• SURMOUNT-4
• SURMOUNT-OSA

SURPASS-2 compared it directly with semaglutide 1 mg, which was the licensed diabetes dose at the time and is not the highest semaglutide dose now available. That comparator choice is the most frequently raised criticism of the head-to-head evidence and it is a fair one.

SURMOUNT-OSA is notable in this class for using a hard, objectively measured endpoint (apnoea-hypopnoea index) rather than a symptom scale, which makes it unusually resistant to the criticisms that attach to softer endpoints.

Individual digests for several of these are maintained separately in this commons and are linked from the evidence category. A digest is a summary with its criticisms attached; it is not a substitute for reading the paper.

Analytical considerations

Reversed-phase HPLC with ultraviolet detection at 214 nm is the usual purity method, and electrospray mass spectrometry the usual identity method. A purity figure is an area percentage at a stated wavelength under a stated gradient, and it is not interchangeable with a content determination.

Three things a purity assay on this compound will not tell you: how much peptide is in the container (that requires a content assay), what the counter-ion is (that requires ion chromatography or NMR), and whether anything is present that does not elute under the method used.

See Reversed-phase HPLC for peptides and LC-MS identity confirmation for the method detail.

Status and legality

Licensed for type 2 diabetes and for weight management in many jurisdictions.

Material sold as research-use-only is not a licensed medicine, whatever it contains and however good its certificate is. That is a statement about regulatory status rather than about quality, and it is true of high-purity material as much as of poor material.

Limitations of this page

This is a reference page maintained by volunteers, reviewed on the date shown, and it will be out of date at some point after that date. It summarises published work rather than reproducing it, and a summary always loses something. Where the summary and the source disagree, the source is right.

If you find an error, the fastest route to fixing it is a topic in doc review naming the sentence and the source. The maintainers named above are notified.