Tirzepatide vs Cagrilintide — Incretin vs Amylin Approach to Weight Reduction

Mechanism side-by-side

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. Structurally, tirzepatide packs both receptor-agonist activities into a single engineered molecule, whereas the cagrilintide research programme has always paired a separate amylin-receptor agonist alongside a separate GLP-1 agonist (semaglutide) in a fixed-ratio pen, rather than engineering both activities into one peptide backbone. That is a meaningful design difference: tirzepatide is a single-molecule dual agonist, while CagriSema is a two-molecule co-formulation.

The early pharmacokinetic groundwork for the cagrilintide/semaglutide co-administration approach was established in Enebo 2021 (Lancet, PMID 33894838), a phase 1b trial evaluating the safety, tolerability, pharmacokinetics and pharmacodynamics of concomitant multiple-dose administration of cagrilintide with semaglutide — the study that de-risked the later phase-3 programme by confirming the two agonists could be administered together without an unexpected PK interaction.

This asymmetry — one molecule engineered to hit two receptors, versus two molecules co-formulated to hit two receptors — also explains why the manufacturers took different development strategies. Eli Lilly's tirzepatide programme evaluated the dual-agonist molecule as a standalone therapy from its earliest trials. Novo Nordisk's cagrilintide programme, by contrast, was designed from the outset around pairing with semaglutide, its existing licensed GLP-1 asset, rather than pursuing amylin-receptor agonism as an independent therapeutic strategy. That commercial and clinical-development choice is a large part of why no cagrilintide monotherapy phase-3 trial exists — it is not that such a trial failed or was abandoned, but that the programme was never structured to produce one.

Why the comparison is structurally asymmetric

A reader coming to this page expecting a clean "drug A vs drug B" comparison should understand that the asymmetry described above is not an artefact of incomplete research — it reflects two genuinely different development strategies. Tirzepatide's evidence base answers the question "how effective is dual GIP/GLP-1 agonism in a single molecule." Cagrilintide's evidence base, because it was never tested alone, cannot answer the equivalent question "how effective is amylin-receptor agonism alone" — it can only answer "how effective is amylin-receptor agonism added on top of GLP-1 agonism." Those are different scientific questions, and conflating them risks over- or under-crediting cagrilintide's independent contribution to the outcomes reported in REDEFINE 1 and REDEFINE 2.

Evidence base — head-to-head vs single-arm

No published trial has compared tirzepatide directly against cagrilintide or CagriSema in the same study population; the comparison on this page is necessarily a comparison of separate evidence bases rather than a shared head-to-head trial.

Tirzepatide. SURMOUNT-1 (Jastreboff 2022, NEJM, PMID 35658024) 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). This is the deepest, most regulatorily mature evidence base discussed on this page — phase-3 outcome data followed by full marketing authorisation and years of accumulating real-world prescribing experience.

Cagrilintide. No phase-3 monotherapy trial exists for cagrilintide alone — this is a structural feature of its development programme, not a gap in the literature search. The evidence base is dominated by REDEFINE 1 (obesity, Garvey 2025 NEJM, PMID 40544433), REDEFINE 2 (obesity + T2D, Davies 2025 NEJM, PMID 40544432), and the REIMAGINE 1-3 series in T2D — all of which report on the CagriSema fixed-ratio combination, not cagrilintide alone, building on the earlier PK/PD groundwork in Enebo 2021. Any statement about "cagrilintide's effect" is therefore, in the published literature, actually a statement about the combination's effect, since no monotherapy trial has isolated cagrilintide's independent contribution.

Clinical use cases

Tirzepatide is a licensed medicine with a clear regulatory pathway. Its evidence base and prescribing context are established for both type-2 diabetes and obesity indications. A UK reader researching a currently-available prescription option would be researching Mounjaro / Zepbound and the associated NHS or private prescribing pathway.

Cagrilintide (as CagriSema) is an investigational combination with published phase-3 outcome data but no marketing authorisation anywhere as of the dates covered in this page's reference list. It is not a real-world prescribing option; it is a research literature to read for researchers tracking where the incretin-plus-amylin combination class is heading, and for understanding the mechanistic rationale for combining GLP-1 and amylin agonism.

Safety signals compared

Tirzepatide's safety profile is the more extensively documented of the two, drawing on SURMOUNT-1 and the SURPASS programme plus post-approval pharmacovigilance accumulated since MHRA licensing. Cagrilintide's safety data, by contrast, is inseparable from CagriSema's combination safety data — Enebo 2021 established the early tolerability signal for co-administration, and REDEFINE 1/2 report the combination's adverse-event profile in phase-3 populations, but no trial in this page's reference list isolates cagrilintide's standalone safety profile apart from the semaglutide co-administration. A reader looking for "cagrilintide safety data" specifically will not find it separated from the combination in the current published record.

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.

This page is a research-evidence review, not a comparison of two products a UK reader can currently choose between for personal use. Only the tirzepatide side of this comparison corresponds to a medicine available through a UK prescribing pathway.

Verdict / Which to choose (or neither)

These are not directly interchangeable, and "which to choose" is not really the right frame for a UK reader today. Tirzepatide is a licensed monotherapy with a mature evidence base (SURMOUNT-1, SURPASS) and an active UK prescribing pathway. Cagrilintide has no monotherapy licence, no monotherapy phase-3 evidence, and its entire published clinical evidence is inseparable from its combination with semaglutide as CagriSema (Enebo 2021, Garvey 2025, Davies 2025). The correct comparison for a head-to-head between the two pharmacological approaches at the combination level is Tirzepatide vs Semaglutide alongside the CagriSema stack review — not a direct tirzepatide-vs-cagrilintide-alone comparison, since cagrilintide alone is not a studied clinical entity. A prospective head-to-head trial between tirzepatide and the full CagriSema combination has not been published in this page's reference list.

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