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PeptideHormone

Tirzepatide

A dual GIP and GLP-1 receptor agonist — the first of the co-agonists.

Also known as Mounjaro, Zepbound.

AnalogEstablishedBased on Glucose-dependent insulinotropic polypeptideCompare with GIP Compare lineage

One chain speaking to two receptors at once: the first strong evidence that combining signals beats shouting a single one louder.

Identity

Class
Dual GIP/GLP-1 receptor agonist (39 aa, acylated)
Source
Synthetic; engineered on a GIP backbone
Receptor
GIP receptor + GLP-1 receptor

Key properties

Evidence floorClinicalREF1CLIN1
Molecular weight
~4,813.5 Da
REF
Half-life (native)
~5 days (~120 h)
CLIN
Model dosing

Approximate values for the native hormone; engineered analogs are often deliberately larger and far longer-acting. Each figure carries its own provenance tier, and the floor is the weakest of them - the Standard.

Mechanism

Tirzepatide activates both the GIP and GLP-1 receptors from a single GIP-based, acylated peptide, with a half-life of about five days. Engaging two incretin pathways at once is studied for metabolic effects beyond either alone — the rationale behind incretin co-agonism.

GCGRnot engagedTirzepatideone peptideGLP-1RSatiety · insulinGIPRInsulin · adipose
One peptide, two receptor arms — the incretin chord. The glucagon slot sits empty by design; playing that third note is exactly the step retatrutide takes.

In depth

Tirzepatide is the two-note version of the metabolic idea. A GLP-1 agonist plays a single receptor; tirzepatide adds the GIP receptor and plays both from one acylated peptide — the first co-agonist to reach the clinic, and the proof that combining incretin signals in a single molecule is not just tidy chemistry but better medicine.

The engineering tell is the backbone: rather than bolt GIP activity onto a GLP-1 peptide, the molecule is built on a GIP scaffold that also fits the GLP-1 receptor, with a fatty-acid chain that binds albumin and stretches the half-life to about five days for once-weekly dosing. GIP's biology had long been the awkward incretin — its role in obesity genuinely contested — so agonising it alongside GLP-1 was a real bet, not an obvious one.

The bet paid. Against a GLP-1-only agonist in a head-to-head trial, the two-note molecule won on weight — the clearest evidence that the second receptor earns its keep. That result is the whole premise behind the next step: if two notes beat one, does a third beat two? Retatrutide adds the glucagon receptor to find out — which is why the empty glucagon slot in the figure above is worth staring at.

Reference notes

  • The first approved 'twincretin' — one molecule with dual GIP/GLP-1 agonism (Mounjaro for type 2 diabetes, 2022; Zepbound for obesity, 2023).
  • Built on a GIP backbone with fatty-acid acylation for once-weekly dosing.
  • In the SURMOUNT-1 obesity trial the highest dose reduced body weight by about a fifth at 72 weeks — the result that put co-agonism on the map.
  • In SURMOUNT-5, a head-to-head trial, it outperformed a GLP-1-only agonist (semaglutide) on weight — direct evidence that the second receptor earns its place.

Common questions

What is Tirzepatide?
A dual GIP and GLP-1 receptor agonist — the first of the co-agonists. Structurally it is Dual GIP/GLP-1 receptor agonist (39 aa, acylated).
How does Tirzepatide work?
Tirzepatide activates both the GIP and GLP-1 receptors from a single GIP-based, acylated peptide, with a half-life of about five days. Engaging two incretin pathways at once is studied for metabolic effects beyond either alone — the rationale behind incretin co-agonism.
How strong is the evidence for Tirzepatide?
PeptideHormone grades Tirzepatide at the "Established" evidence tier — its mechanism and core effects are settled across the peer-reviewed literature. It is catalogued as an engineered analog built on an endogenous hormone, and the tier is an editorial judgment about the public literature that can change as the science does.
What is the half-life of Tirzepatide?
The reported circulating half-life of Tirzepatide is ~5 days (~120 h).
Is Tirzepatide the same as Mounjaro or Zepbound?
Mounjaro, and Zepbound are brand names of Tirzepatide — the same molecule in different approved presentations. This page is the molecule reference, not a prescribing guide.

Selected literature

Curated peer-reviewed reviews, sourced from PubMed. Selected for relevance, not exhaustive — open any entry on PubMed for the full record and its primary citations.

  1. 1.Tirzepatide for overweight and obesity management · Expert opinion on pharmacotherapy, 2025 · PMID 39632534
  2. 2.Subcutaneously administered tirzepatide vs semaglutide for adults with type 2 diabetes: a systematic review and network meta-analysis of randomised controlled trials · Diabetologia, 2024 · PMID 38613667

External references

Tirzepatide in the public knowledge graph — the same entity resolved across the authoritative chemistry and protein databases.