What Is Cagrilintide? The Amylin Analog Behind CagriSema

Cagrilintide is a long-acting amylin receptor agonist developed by Novo Nordisk. It is a once-weekly injectable peptide that mimics amylin, a hormone naturally co-secreted with insulin from the pancreas after meals. Amylin reduces appetite, slows gastric emptying, and suppresses glucagon — a fundamentally different mechanism from GLP-1 receptor agonists like semaglutide and tirzepatide.

Cagrilintide is best known as one half of CagriSema, Novo Nordisk's combination of cagrilintide + semaglutide. In the REDEFINE 1 Phase 3 trial, cagrilintide as monotherapy produced 11.5% weight loss at 68 weeks — meaningful on its own, and additive when combined with semaglutide (20.4% as CagriSema). An NDA for CagriSema was filed with the FDA in December 2025.

As a standalone compound, cagrilintide has gained attention in biohacker and peptide communities, where people are stacking it with tirzepatide and other GLP-1 drugs. This article covers cagrilintide itself — how it works, what the clinical data shows, and how it compares to the incretin-based drugs most people are already familiar with.

How Cagrilintide Works

Cagrilintide targets a completely different receptor system than GLP-1 drugs. While semaglutide, tirzepatide, and retatrutide all work through incretin receptors (GLP-1, GIP, glucagon), cagrilintide works through amylin receptors in the brain.

The Amylin Pathway

Amylin is a 37-amino-acid peptide hormone co-secreted with insulin by pancreatic beta cells after meals. It was discovered in 1987 and has three main effects:

• Reduces appetite by acting on the area postrema and hypothalamus in the brain
• Slows gastric emptying, prolonging the feeling of fullness after eating
• Suppresses post-meal glucagon secretion, preventing the liver from releasing excess glucose after meals

In people with type 2 diabetes, amylin secretion is reduced — just like insulin. In obesity, the amylin signaling pathway may become less effective over time.

What Makes Cagrilintide Different From Native Amylin

Native human amylin has a half-life of roughly 13 minutes — far too short for practical use as a medication. Cagrilintide solves this with structural modifications that extend its half-life to approximately 7 days, enabling once-weekly dosing.

Specifically, cagrilintide is an acylated analog with a C18 fatty diacid side chain (similar to the pharmacological strategy used in semaglutide and tirzepatide). This modification allows it to bind albumin in the bloodstream, creating a slow-release depot effect.

Receptor Binding

A 2025 study in Nature Communications determined the cryo-EM structures of cagrilintide bound to its target receptors. Cagrilintide activates:

• AMY1R (amylin receptor 1) — calcitonin receptor + RAMP1
• AMY2R (amylin receptor 2) — calcitonin receptor + RAMP2
• AMY3R (amylin receptor 3) — calcitonin receptor + RAMP3
• CTR (calcitonin receptor) — the base receptor without RAMP proteins

A separate 2025 study in eBioMedicine confirmed that cagrilintide lowers body weight primarily through brain AMY1R and AMY3R.

The key point: amylin receptors are entirely separate from GLP-1, GIP, and glucagon receptors. This is why cagrilintide can produce additional weight loss when combined with drugs that target those incretin pathways.

Clinical Trial Data

Phase 2 (Monotherapy)

A Phase 2 dose-finding trial studied cagrilintide monotherapy in adults with overweight or obesity (BMI 27+) without diabetes. Published results showed dose-dependent weight loss over 26 weeks:

The 2.4 mg dose was selected for Phase 3 development, balancing efficacy against tolerability.

REDEFINE 1 (Phase 3a — Obesity Without Diabetes)

The landmark REDEFINE 1 trial was a 68-week, double-blind, placebo-controlled trial in 3,417 adults without diabetes. It included cagrilintide as monotherapy, semaglutide as monotherapy, and the CagriSema combination. Results:

Cagrilintide monotherapy produced meaningful weight loss (11.5%), though less than semaglutide alone (14.9%). The combination was clearly additive — the extra amylin pathway provided roughly 5-6 additional percentage points of weight loss on top of semaglutide.

REDEFINE 2 (Phase 3a — Type 2 Diabetes)

In adults with type 2 diabetes and overweight/obesity, CagriSema produced -13.7% weight loss at 68 weeks (vs -3.4% for placebo). HbA1c reduction was also significant: 73.5% of CagriSema participants achieved HbA1c of 6.5% or below, compared to 15.9% on placebo.

REDEFINE 4 (Head-to-Head vs Tirzepatide)

The REDEFINE 4 trial compared CagriSema directly to tirzepatide 15 mg over 84 weeks. CagriSema achieved 23.0% weight loss vs 25.5% for tirzepatide (in the adherence analysis), failing to demonstrate non-inferiority. This result is for CagriSema as a combination — not cagrilintide alone.

Cagrilintide Dosage

Cagrilintide uses a titration schedule to minimize gastrointestinal side effects. Based on the REDEFINE program, the dosing schedule is:

The maintenance dose is 2.4 mg once weekly by subcutaneous injection. This is the dose used in all Phase 3 REDEFINE trials. In Phase 2, a 4.5 mg dose was also tested but was not advanced to Phase 3, likely due to the balance of efficacy vs side effects.

Cagrilintide Side Effects

The side effect profile of cagrilintide is broadly similar to GLP-1 drugs, with gastrointestinal symptoms being the most common.

From REDEFINE 1 (CagriSema vs Placebo)

Most GI side effects were mild to moderate and concentrated during the dose escalation period. Injection site reactions were also reported, which is a more specific signal for cagrilintide (amylin analogs are known for this).

Serious adverse events were low and comparable across treatment groups. No new safety signals were identified compared to semaglutide alone.

How Cagrilintide Compares to Other Weight Loss Drugs

The critical distinction is that cagrilintide works through amylin receptors, not incretin receptors. It does not directly compete with semaglutide, tirzepatide, or retatrutide — it complements them. This is exactly why Novo Nordisk developed CagriSema: combining the amylin pathway (cagrilintide) with the GLP-1 pathway (semaglutide) produces more weight loss than either drug alone.

Why People Are Interested in Cagrilintide

Stacking With GLP-1 Drugs

The biggest driver of interest is the idea of adding cagrilintide to an existing GLP-1 or dual agonist regimen. Because cagrilintide targets entirely different receptors, it can theoretically provide additive appetite suppression on top of tirzepatide, semaglutide, or even retatrutide.

The REDEFINE 1 data supports this — CagriSema (cagrilintide + semaglutide) produced 20.4% weight loss vs 14.9% for semaglutide alone. The amylin pathway added roughly 5.5 extra percentage points.

For a deeper look at stacking cagrilintide with tirzepatide, see our dedicated article on cagrilintide and tirzepatide.

Plateau Breaker

Some users on GLP-1 drugs report weight loss plateaus after 6-12 months. The theory is that adding an amylin analog could restart weight loss by engaging a pathway the body has not yet adapted to. No clinical trial has specifically studied this use case, but the pharmacological rationale exists.

Different Side Effect Profile

For people who experience severe GI side effects on GLP-1 drugs, cagrilintide as monotherapy may offer an alternative pathway with a somewhat different tolerability profile. It still causes GI side effects, but the pattern differs (more injection site reactions, potentially less severe nausea at equivalent weight loss levels).

Cagrilintide vs Retatrutide

This is an important comparison for readers of this site. Retatrutide achieves 28.7% weight loss from a single molecule that activates three incretin-related receptors (GLP-1, GIP, glucagon). Cagrilintide achieves 11.5% from a single molecule that activates amylin receptors — a completely different pathway.

The drugs are not directly competitive. They could theoretically be complementary: retatrutide covers the incretin/glucagon pathways, while cagrilintide covers the amylin pathway. No trial has studied this combination, and it is unlikely to be studied given the drugs are made by competing companies (Lilly vs Novo Nordisk).

For a full comparison of retatrutide vs the CagriSema combination (cagrilintide + semaglutide), see retatrutide vs CagriSema.

Current Status and Availability

• Not FDA approved as a standalone drug
• NDA filed as part of CagriSema (cagrilintide + semaglutide) in December 2025
• Expected FDA decision for CagriSema: 2026
• Available as a research peptide through gray market suppliers — but with significant quality and safety risks (no regulatory oversight, unknown purity, no clinical dosing guidance for off-label stacking)

Cagrilintide is not expected to be approved or marketed as a standalone medication. Novo Nordisk's regulatory strategy centers on CagriSema as the commercial product.

Frequently Asked Questions

Sources

1. Garvey WT, et al. "Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity." New England Journal of Medicine. 2025;393:635-647. NEJM
2. Carvas AO, et al. "Cagrilintide lowers bodyweight through brain amylin receptors 1 and 3." eBioMedicine. 2025;118:105836. PMC
3. Cao J, et al. "Structural and dynamic features of cagrilintide binding to calcitonin and amylin receptors." Nature Communications. 2025;16:3456. Nature
4. Dutta D, et al. "Efficacy and Safety of Cagrilintide Alone and in Combination with Semaglutide as Anti-Obesity Medications: A Systematic Review." Indian J Endocrinol Metab. 2024;28(5):436-444. PMC
5. Novo Nordisk. "CagriSema demonstrated 23% weight loss in REDEFINE 4 trial." February 2026. Press Release

This article is for informational purposes only and does not constitute medical advice. Cagrilintide is an investigational compound. Always consult a healthcare provider before starting any medication.