Tirzepatide vs Cagrilintide — Incretin vs Amylin Approach to Weight Reduction

Mechanism differentiation

Tirzepatide is a dual agonist at the GIP and GLP-1 receptors. GLP-1 receptor activation drives satiety and slows gastric emptying via vagal afferents and hypothalamic circuits; GIP receptor activation adds an adipocyte-directed component that is thought to contribute to the differential weight response versus GLP-1 monotherapy.

Cagrilintide is a long-acting agonist at the amylin receptor (AMY1R/AMY3R heterodimers of the calcitonin receptor with RAMP subunits) and the calcitonin receptor. Amylin's satiety signal is mediated largely via area postrema and hindbrain circuits, distinct from GLP-1's hypothalamic action. The rationale for combining cagrilintide with semaglutide (CagriSema) is that these two satiety pathways are partially independent — additive rather than merely overlapping.

The direct pharmacological comparison, then, is not really "GIP+GLP-1 vs amylin" — it's "GIP+GLP-1 vs amylin+GLP-1", because cagrilintide is only being developed in combination.

Evidence base

Tirzepatide. SURMOUNT-1 (Jastreboff 2022, NEJM) reported roughly 21% mean weight reduction on 15 mg weekly in adults with overweight or obesity without T2D over 72 weeks. The SURPASS programme covers T2D. UK MHRA authorised for both indications; sold as Mounjaro (T2D) and Zepbound (obesity).

Cagrilintide. No phase-3 monotherapy trial. The evidence base is dominated by REDEFINE 1 (obesity, Garvey 2025 NEJM), REDEFINE 2 (obesity + T2D, Davies 2025 NEJM), and the REIMAGINE 1-3 series in T2D (2026 Lancet family) — all of which report on the CagriSema fixed-ratio combination, not cagrilintide alone.

When each pharmacological approach might apply

Tirzepatide is a licensed medicine with a clear regulatory pathway. Its evidence base and prescribing context are established. A UK reader searching for a currently-available prescription option would be researching Mounjaro / Zepbound.

Cagrilintide (as CagriSema) is an investigational combination with published phase-3 outcome data but no marketing authorisation. It's not a real-world option today; it's a research literature to read if you're tracking where the incretin+amylin combination class is going.

UK regulatory context

• Tirzepatide: licensed. Wegovy/Ozempic-equivalent regulatory framework applies. Public-facing weight-loss advertising is constrained under MHRA POM-medicine advertising rules.
• Cagrilintide / CagriSema: unlicensed. Any UK-facing promotion as a weight-loss product would fall foul of both the MHRA rules and ASA codes. See our weight-loss medicine advertising caution.

Related pages

• Tirzepatide monograph
• Cagrilintide monograph
• Semaglutide monograph
• CagriSema stack review
• CagriSema mechanism explainer
• Tirzepatide vs Semaglutide

Verdict — research-question matching

These are not directly interchangeable. Tirzepatide is a licensed monotherapy; cagrilintide has no monotherapy licence and its clinical evidence is inseparable from its combination with semaglutide (CagriSema). The correct comparison for a head-to-head between the two pharmacological approaches at the combination level is Tirzepatide vs CagriSema — not vs cagrilintide alone. A prospective head-to-head trial between the two full combinations has not been published as of 2026-07.

References

Peer-reviewed sources for the claims above. Where an editor has verified study type, sample size, outcome and limitation, the citation is rendered as a card; otherwise as a plain reference. Links open PubMed or the journal DOI.

1. Jastreboff AM, Aronne LJ, Ahmad NN, et al. (SURMOUNT-1 Investigators). Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine. 2022;387(3) :205-216 doi:10.1056/NEJMoa2206038 · PMID: 35658024
2. Garvey WT, Blüher M, et al.. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2025 · PMID: 40544433
3. Davies MJ, Bajaj HS, et al.. Cagrilintide-Semaglutide in Adults with Overweight or Obesity and Type 2 Diabetes. New England Journal of Medicine. 2025 · PMID: 40544432
4. Enebo LB, Berthelsen KK, Kankam M, et al.. Safety, tolerability, pharmacokinetics, and pharmacodynamics of concomitant administration of multiple doses of cagrilintide with semaglutide 2·4 mg for weight management: a randomised, controlled, phase 1b trial. Lancet (London, England). 2021;397(10286) :1736-1748 · PMID: 33894838