Everything you need to know about the next generation of obesity treatment — and what happens when it’s combined with a GLP-1.
Cagrilintide is a long-acting analogue of amylin — a naturally occurring hormone produced by the pancreas — developed by Danish pharmaceutical company Novo Nordisk. It is designed to be administered once weekly via a subcutaneous injection, and its primary purpose is the treatment of obesity and overweight.
Unlike GLP-1 receptor agonists such as semaglutide (Wegovy) or tirzepatide (Mounjaro), which target hormones released from the gut, cagrilintide works through a completely different pathway. It mimics the action of amylin, a hormone that plays a distinct but complementary role in appetite control and energy regulation. This difference in mechanism is precisely why researchers became so interested in combining cagrilintide with GLP-1 therapy.
On its own, cagrilintide showed meaningful weight loss in Phase 2 clinical trials. But its real promise emerged when it was paired with semaglutide — producing results that neither drug could achieve alone. That combination, known as CagriSema, became one of the most closely watched developments in obesity pharmacology.
To understand cagrilintide, you first need to understand amylin — the hormone it is designed to mimic.
Amylin (also called islet amyloid polypeptide, or IAPP) is a 37-amino acid peptide hormone co-secreted by the beta cells of the pancreas alongside insulin, typically in response to meals. It was identified in the late 1980s and initially attracted attention because its deposits are found in the pancreases of people with type 2 diabetes. Over time, however, researchers came to understand that amylin has a distinct and important set of functions in regulating metabolism and food intake.
Natural amylin acts across several key systems in the body. It slows gastric emptying — the rate at which food leaves the stomach — which helps moderate the post-meal rise in blood glucose. It suppresses the release of glucagon, the hormone that signals the liver to release glucose into the bloodstream. And critically for obesity research, it acts centrally: amylin binds to receptors in the area postrema and the brainstem, where it generates satiety signals that communicate to the brain that the body has had enough to eat.
The problem with natural amylin, as a therapeutic agent, is its short half-life. It degrades rapidly in the bloodstream, making it impractical as a daily medication without significant modification. The existing amylin analogue pramlintide (sold as Symlin in the US for diabetes management) requires multiple daily injections. Cagrilintide addresses this limitation directly: through chemical modifications to the amylin molecule, Novo Nordisk’s scientists created a compound with a half-life of approximately seven days — long enough for once-weekly dosing.
Cagrilintide exerts its effects by binding to amylin receptors — specifically the calcitonin receptor in combination with receptor activity-modifying proteins (RAMP1 and RAMP3). These receptor complexes are found in several key locations throughout the body, including the brain, stomach, and kidney. The downstream effects of activating these receptors produce a coordinated set of responses that collectively reduce body weight.
Cagrilintide acts on the area postrema and hypothalamus, key brain centres involved in hunger and satiety. By activating amylin receptors here, it generates a sustained feeling of fullness that reduces overall calorie intake — independent of GLP-1 signalling pathways.
By slowing the rate at which food moves from the stomach to the small intestine, cagrilintide extends the sensation of fullness after meals and moderates the speed at which glucose enters the bloodstream. This also contributes to reduced food intake at subsequent meals.
Cagrilintide reduces postprandial glucagon secretion. Glucagon normally signals the liver to release stored glucose, so suppressing it after meals helps prevent unnecessary elevations in blood sugar — particularly useful in people with insulin resistance or type 2 diabetes.
Amylin receptor signalling in the brain works through different neural circuits than GLP-1 receptor signalling. This means cagrilintide and GLP-1 agonists are not competing for the same mechanism — they are engaging the appetite-regulation system through separate but reinforcing pathways, which underpins the rationale for their combination.
What makes cagrilintide particularly interesting from a pharmacological standpoint is that it appears to produce a preferential loss of fat mass rather than lean mass — a finding observed in preclinical and clinical studies. Preserving muscle while losing fat is a major therapeutic goal in obesity medicine, as loss of muscle mass can worsen metabolic function and long-term outcomes.
To fully appreciate the significance of combining cagrilintide with a GLP-1 agonist, it helps to understand what GLP-1 drugs do — and, crucially, what they do not do.
GLP-1 (glucagon-like peptide-1) is an incretin hormone secreted by L-cells in the gut wall in response to food. It plays a central role in the body’s post-meal response: it stimulates insulin secretion from the pancreas, suppresses glucagon release, slows gastric emptying, and sends satiety signals to the brain. GLP-1 receptor agonists such as semaglutide (the active ingredient in Ozempic and Wegovy) are synthetic molecules that mimic these actions with much longer half-lives than the natural hormone.
In clinical trials, GLP-1 receptor agonists have demonstrated substantial and clinically meaningful weight loss. In the STEP 1 trial, semaglutide 2.4mg produced an average body weight reduction of approximately 14.9% at 68 weeks in people with obesity. These are results that surpass virtually every previous pharmacological approach to weight management.
Yet GLP-1 agonists have a ceiling. Not every patient achieves the weight loss targets they are hoping for, and a meaningful proportion of patients — even on maximum doses — do not reach the 15–20% body weight reduction that clinical guidelines increasingly use as a benchmark for meaningful metabolic benefit. There is also the question of what happens when GLP-1 therapy is eventually stopped: weight tends to return, suggesting that the underlying biology of obesity has not been fundamentally altered.
CagriSema is the fixed-dose co-formulation of cagrilintide 2.4mg and semaglutide 2.4mg developed by Novo Nordisk, delivered as a single once-weekly subcutaneous injection. The rationale for combining these two agents is deeply rooted in the complementary biology described above.
Semaglutide acts primarily via GLP-1 receptors in the gut and brain, reducing appetite largely through GLP-1 receptor-mediated pathways. Cagrilintide acts via amylin receptors, which are anatomically and mechanistically distinct. Together, they engage two separate hormonal systems that both regulate body weight — creating an additive, and potentially synergistic, effect on appetite suppression and calorie reduction.
Think of it this way. If GLP-1 therapy turns down one volume knob on the brain’s hunger signal, cagrilintide turns down a different, parallel volume knob. Neither alone can reduce the signal as much as both together. This is not duplication — it is genuinely complementary pharmacology operating on different receptor systems in different neural circuits.
Obesity is regulated by at least six distinct appetite-controlling hormonal systems. GLP-1 therapies address one of them particularly well. Cagrilintide addresses a second, independent system. Targeting both simultaneously has the potential to produce weight loss outcomes that neither drug could achieve alone — without simply doubling the side effects.
Beyond appetite, the combination also offers metabolic breadth. Semaglutide improves insulin sensitivity and has demonstrated cardiovascular benefits in people with type 2 diabetes. Cagrilintide contributes glucagon suppression and its own favourable effects on glucose regulation. Together, the metabolic profile of CagriSema addresses obesity not just as a question of body weight, but as a broader disorder of metabolic function.
The Phase 2 clinical trial for cagrilintide monotherapy was published in The Lancet in 2021. This randomised, double-blind, placebo-controlled trial enrolled 706 adults with overweight or obesity (BMI 27 or above) across multiple dose groups, running over 26 weeks.
Participants in the highest dose group (4.5mg weekly) achieved a mean body weight reduction of approximately 10.8% from baseline, compared to around 3% in the placebo group. Crucially, the weight loss trajectory at 26 weeks had not plateaued — suggesting that longer treatment duration would produce further reductions. These results established cagrilintide as a clinically meaningful agent in its own right, while also confirming that its mechanism was distinct enough from existing therapies to warrant combination investigation.
The Phase 2 trial of CagriSema was published in The Lancet in 2023, and its results attracted immediate attention. The trial enrolled adults with overweight or obesity and randomised them to receive CagriSema, cagrilintide alone, semaglutide alone, or placebo over 32 weeks.
The combination significantly outperformed both monotherapies. Participants on CagriSema achieved a mean body weight reduction of approximately 15.6% from baseline — substantially greater than either semaglutide or cagrilintide administered alone. This was particularly notable because semaglutide 2.4mg, used alone, already represents one of the most effective pharmacological weight loss treatments available. The fact that adding cagrilintide produced meaningfully greater weight loss over just 32 weeks confirmed the additive effect of the dual mechanism.
The trial also showed that the combination produced dose-dependent, sustained weight loss without concerning additional adverse effects — the side effect profile was broadly consistent with what would be expected from each individual agent.
The Phase 3 programme for CagriSema is conducted under the name REDEFINE — a series of large, randomised, controlled trials designed to confirm efficacy and establish the safety profile required for regulatory approval.
| Trial | Population | Duration | Primary endpoint |
|---|---|---|---|
| REDEFINE 1 | Adults with obesity (no diabetes) | 68 weeks | % body weight change from baseline |
| REDEFINE 2 | Adults with overweight/obesity and type 2 diabetes | 68 weeks | % body weight change + HbA1c reduction |
| REDEFINE 3 | Adults with cardiovascular disease and overweight/obesity | Multi-year MACE outcome trial | Major adverse cardiovascular events |
REDEFINE Phase 3 programme overview. MACE = major adverse cardiovascular events.
REDEFINE 1 — the pivotal efficacy trial in adults with obesity without diabetes — reported top-line results in early 2025. CagriSema 2.4/2.4mg produced a mean body weight reduction of approximately 22.7% from baseline at 68 weeks, compared to around 2–3% with placebo. This figure is directly comparable to the performance of tirzepatide (Mounjaro) in the SURMOUNT-1 trial, which showed approximately 20.9% weight loss at 72 weeks, and exceeds the approximately 14.9% achieved by semaglutide alone in STEP 1.
Importantly, REDEFINE 1 also showed that a significant proportion of participants achieved ≥25% body weight reduction — a threshold that, in clinical terms, represents the kind of weight loss previously achievable only through bariatric surgery.
The side effect profile of CagriSema largely reflects what is already known from its two component drugs, with gastrointestinal effects being the most commonly reported. These are consistent with the mechanism of action — slowing gastric emptying affects digestion, and central appetite suppression can cause nausea, particularly during the early stages of treatment and dose escalation.
In the Phase 3 REDEFINE 1 trial, the most commonly reported adverse events included nausea, vomiting, diarrhoea, and constipation. These effects were generally mild to moderate in intensity and were most frequent during the dose escalation period, becoming less common as participants remained on their maintenance dose. The rate of treatment discontinuation due to adverse events was comparable to what has been observed in trials of GLP-1 monotherapy.
Injection site reactions were observed in a minority of participants, consistent with other subcutaneous injectable weight loss medications. No new or unexpected safety signals emerged from the Phase 3 data that had not already been identified in Phase 2.
| Side effect | Frequency | When most common | Management |
|---|---|---|---|
| Nausea | Very common | During dose escalation | Small meals, slow titration |
| Vomiting | Common | Early treatment phase | Dietary adjustments; usually resolves |
| Diarrhoea | Common | Variable | Hydration; usually self-limiting |
| Constipation | Common | Maintenance phase | Increased fluid and fibre intake |
| Injection site reaction | Uncommon | Any time | Rotate injection sites |
| Decreased appetite | Very common | Throughout treatment | Expected; therapeutic effect |
As of the date of publication, CagriSema has not received regulatory approval from any major health authority, including the MHRA (UK), EMA (Europe), or FDA (United States). It remains an investigational medicinal product. This means it is not available through any legitimate pharmacy — in the UK or elsewhere — outside of a clinical trial setting.
Novo Nordisk has indicated its intention to submit CagriSema for regulatory review following the completion of the REDEFINE Phase 3 programme. The REDEFINE 3 cardiovascular outcomes trial — which will take several years to complete — is not a prerequisite for initial market authorisation for obesity treatment, but its results will likely be important for subsequent label expansion and for establishing the cardiovascular benefit profile that has proven so valuable for tirzepatide and semaglutide.
If regulatory submissions proceed as expected, the earliest plausible timeline for a market authorisation decision in the UK or Europe would be 2026 or 2027 — though this is subject to the pace of regulatory review, the completeness of the submission package, and any additional data requests from the MHRA or EMA. The NHS access journey, should CagriSema receive approval, would then follow a separate NICE appraisal process — the same pathway that Wegovy and Mounjaro have navigated.
For people currently managing obesity and who are not yet on treatment — or who are on GLP-1 therapy but not achieving their desired outcomes — the most appropriate step is a conversation with a qualified healthcare professional. Approved and clinically evidenced options, including semaglutide and tirzepatide, remain available now through regulated channels. The clinical evidence for these drugs is robust and their safety profiles are well-established.
Mohammed Ismail Lakhi MPharm — Superintendent Pharmacist at The Care Pharmacy
GPhC Registration Number: 2072815
All clinical content published by The Care Pharmacy is reviewed by a UK-registered pharmacist to ensure accuracy and alignment with current UK medical guidance. Last reviewed: June 2026
Last updated: June 2026. Information reflects data available at time of publication. Spot an error? Contact us.
Sources
Lau DCW et al. (2021). Lancet — Phase 2 cagrilintide monotherapy trial (PMID 34480864) ·
Enebo LB et al. (2021) — Lancet Diabetes Endocrinol ·
Frias JP et al. (2023) — Phase 2 CagriSema combination, Lancet ·
Novo Nordisk REDEFINE 1 Phase 3 results (2025) ·
European Medicines Agency ·
MHRA
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