Cagrilintide UK: The Amylin Analogue Behind CagriSema

Cagrilintide is a long-acting amylin analogue developed by Novo Nordisk and studied as a once-weekly injectable for weight management, both on its own and combined with semaglutide under the name CagriSema. In a 2021 phase 2 trial published in The Lancet, participants on the highest dose lost an average of 10.8% of body weight over 26 weeks, and the phase 3 REDEFINE 1 trial reported 20.4% with the CagriSema combination over 68 weeks. In the UK, cagrilintide has no MHRA marketing authorisation and is supplied only as a research chemical for laboratory use.

This guide covers what cagrilintide is, how the amylin pathway differs from the GLP-1 class that dominates the headlines, what the published trials reported, where the compound stands in UK law, and what to check when buying cagrilintide in the UK for research.

What is cagrilintide?

Amylin is a 37-amino-acid peptide hormone that the pancreatic beta cells release alongside insulin after a meal. It slows gastric emptying, suppresses glucagon release and signals satiety through the area postrema in the brainstem. Native amylin is a poor drug candidate because it is unstable in solution and readily forms amyloid fibrils, which is why the first amylin-based medicine, pramlintide, was engineered with proline substitutions and still needed to be injected before every meal.

Cagrilintide solves the stability and duration problems differently. It is a lipidated analogue: a fatty di-acid chain is attached to the peptide so that it binds albumin in the blood, which extends its half-life enough for once-weekly administration in trials. Pharmacologically it is described as a dual amylin and calcitonin receptor agonist, or DACRA, because it activates both the amylin receptor complexes and the calcitonin receptor itself. In a research pen it is typically supplied as a clear solution at a stated quantity, such as 10mg, ready for laboratory work.

Amylin vs GLP-1: why the pathway matters

Most of the weight-management compounds UK researchers ask about are GLP-1 receptor agonists (semaglutide), dual GIP/GLP-1 agonists (tirzepatide) or triple agonists (retatrutide). Cagrilintide is not in that family. It works through a separate receptor system, which is precisely why it was investigated in combination with semaglutide: the hypothesis was that two complementary satiety signals would produce greater weight reduction than either alone, and the REDEFINE trials were designed to test that.

The distinction also matters for anyone reading the literature. Trial results for cagrilintide should not be read as GLP-1 results, and the adverse-event profile, while it overlaps on gastrointestinal effects, comes from a different mechanism. The table below places cagrilintide alongside the other amylin-pathway and incretin compounds most often compared with it.

What the cagrilintide trials reported

The key monotherapy dataset is the phase 2 dose-finding study by Lau and colleagues, published in The Lancet in 2021. It enrolled 706 adults with overweight or obesity and no diabetes across 57 sites in ten countries, and compared six weekly doses of cagrilintide (0.3mg to 4.5mg) against placebo and against liraglutide 3.0mg over 26 weeks. Participants on cagrilintide 4.5mg lost a mean of 10.8% of body weight (about 11.5kg) versus 3.0% on placebo and 9.0% on liraglutide. Gastrointestinal adverse events were reported in 41% to 63% of cagrilintide participants compared with 32% on placebo, with nausea the most common (20% to 47% versus 18%).

The phase 3 REDEFINE 1 trial, presented at the American Diabetes Association meeting in June 2025 and published in the New England Journal of Medicine, was much larger: 3,417 adults with overweight or obesity followed for 68 weeks. Participants on CagriSema (cagrilintide 2.4mg plus semaglutide 2.4mg) lost a mean of 20.4% of body weight, compared with 11.5% on cagrilintide 2.4mg alone, 14.9% on semaglutide 2.4mg alone and 3.0% on placebo. Around 60% of CagriSema participants lost at least 20% of body weight.

Two points are worth noting for context. First, Novo Nordisk had guided investors to expect around 25% weight loss, so the 20.4% result was widely reported as falling short of the target even though it exceeded semaglutide alone. Second, REDEFINE 2, in adults with type 2 diabetes, reported a mean loss of 13.7% versus 3.4% on placebo over 68 weeks, in line with the general pattern that people with type 2 diabetes lose less weight on these compounds.

How cagrilintide is used in laboratory research

Outside of the pharmaceutical programme, cagrilintide is a useful tool compound for anyone studying amylin and calcitonin receptor pharmacology. Its long half-life and resistance to fibril formation make it easier to work with than native amylin, and its defined receptor profile lets researchers separate amylin-receptor effects from GLP-1 effects in the same model.

• Receptor pharmacology: binding and signalling assays across the calcitonin receptor and the three amylin receptor subtypes (AMY1, AMY2, AMY3) formed with receptor activity-modifying proteins.
• Feeding and energy-balance studies in rodent models, often alongside a GLP-1 agonist to examine additive or synergistic effects.
• Comparison studies against newer selective amylin agonists such as eloralintide, which was designed to reduce calcitonin receptor activity.
• Formulation and stability research, since lipidated peptides behave differently in solution from unmodified sequences.

Is cagrilintide legal in the UK?

Cagrilintide is legal to buy, sell and possess in the UK as a research chemical. It is not a controlled substance under the Misuse of Drugs Act 1971 and it is not caught by the Psychoactive Substances Act 2016. What it does not have is a marketing authorisation from the MHRA, which means it cannot lawfully be supplied for human medicinal use, marketed with medicinal claims or presented as a treatment under the Human Medicines Regulations 2012.

That distinction is the whole basis of the UK research peptide market. A supplier selling cagrilintide for laboratory research is operating within the law; a supplier selling it as a weight-loss treatment is not. Our guide to whether peptides are legal in the UK covers the framework in more detail. If and when CagriSema receives an authorisation, that licence will apply to the specific pharmaceutical product, not to research-grade material.

Cagrilintide vs eloralintide

The other amylin-pathway compound UK researchers now ask about is eloralintide, Eli Lilly's selective amylin receptor agonist. The scientific difference is receptor selectivity: cagrilintide activates the calcitonin receptor as well as the amylin receptors, while eloralintide was engineered to favour the amylin receptor complexes. Lilly reported phase 2 results in late 2025 showing weight loss of up to around 20% over 48 weeks at the higher doses, which has prompted interest in whether greater selectivity changes the tolerability profile.

For a laboratory, both compounds are legitimate tools and the choice depends on the question. Cagrilintide has the larger published dataset and the combination data with semaglutide; eloralintide is the cleaner probe for amylin-receptor-specific effects. We cover the second compound separately in our eloralintide research article.

What to check before buying cagrilintide in the UK

Cagrilintide is a relatively long, lipidated peptide, which makes it harder and more expensive to synthesise well than a short sequence like GHK-Cu. Poorly made material can contain truncated sequences, incomplete lipidation or deletion impurities that still show up as roughly the right mass. The following checks matter more here than for simpler peptides.

1. Ask for a batch-specific certificate of analysis showing HPLC purity and mass spectrometry identity. Calibre pens are tested by Janoshik Analytical and COAs are published on the site's COA page.
2. Confirm the stated quantity refers to peptide content, not the gross weight of the pen, and that the purity target is above 99%.
3. Prefer a pre-filled, precision-made pen if your workflow needs consistent volumes without reconstituting lyophilised powder.
4. Check that the supplier sells for research use only and does not make medicinal claims; that is a signal of a compliant operation.
5. Store the pen refrigerated and away from light, and read our storage guide for pre-filled pens before the material arrives.

Summary

Cagrilintide is the best-characterised long-acting amylin analogue in the literature, with a 706-participant phase 2 trial and a 3,417-participant phase 3 trial behind it. It works through the amylin and calcitonin receptors rather than the GLP-1 receptor, which is why it was paired with semaglutide in CagriSema. In the UK it is legal to buy as a research chemical, has no MHRA authorisation, and should only be sourced with a batch-specific certificate of analysis for laboratory work.