Peptide 101: Cagrilintide

Almost every weight-loss drug in the news right now copies the same hormone: GLP-1. Semaglutide does it. Tirzepatide does it. Retatrutide does it. This week’s column explains a different one — and it is the reason you keep seeing the name CagriSema without ever quite hearing what the “Cagri” part is.

Peptide 101: Cagrilintide

Cagrilintide is a long-acting copy of amylin, made by Novo Nordisk and developed for obesity.

Amylin is worth knowing about on its own. Your pancreas releases it from the same beta cells that release insulin, at the same time, after you eat. Insulin gets all the attention because it moves glucose. Amylin does the behind-the-scenes half of the job: it tells your brain you have eaten, slows how fast your stomach empties, and tells the liver to stop pouring out more sugar.

So amylin and GLP-1 help you arrive at a similar destination — you feel full sooner and eat less — via different roads. That is the whole strategic idea behind cagrilintide. If you can pull two separate satiety levers at once, you may get further than pulling either one hard.

Which is why cagrilintide is mostly discussed as half of a pair. Combined with semaglutide, it becomes CagriSema, and that combination is what has carried it into large phase 3 trials.

How it works

Think of amylin as your body’s “I’ve eaten” message, sent once per meal and gone within hours. Cagrilintide is that same message rebuilt to last, so it stays switched on across a week instead of an afternoon.

The technical version: cagrilintide is an agonist at the amylin receptors AMY1 and AMY3 — the calcitonin receptor paired with receptor activity-modifying proteins (RAMPs). It acts on the area postrema (a small structure in the brainstem that acts as a sensor for toxins in the blood and triggers vomiting) and the hypothalamus, brain regions that govern appetite and nausea. Downstream, that suppresses appetite, slows gastric emptying, and blunts the glucagon rise after a meal. The molecule is also acylated, a modification that keeps it in circulation long enough for once-weekly dosing.

What the evidence shows

Our read on the overall strength of the evidence: Emerging. That is a deliberate grade. There is real human trial data here, which puts cagrilintide well ahead of most peptides we cover — but the headline results still lean on the combination rather than the drug by itself.

What that rests on:

• Phase 2 dose-finding trial (2021) — Once-weekly cagrilintide produced up to roughly 10.8% mean weight loss over 26 weeks, more than liraglutide 3 mg in the same study.
• CagriSema in type 2 diabetes (2023) — The combination lowered HbA1c and body weight more than semaglutide alone.
• Brainstem mechanism work (2026) — A cross-species brainstem atlas pointed to Calcr/Prlh neurons in the dorsal vagal complex as the cells mediating cagrilintide’s effect on food intake and body weight. This was done in rodents and primates, so treat it as a mechanism study, not an outcome study.

The caveat on that middle bullet: showing CagriSema beats semaglutide does not tell you how much of the gain came from the cagrilintide half. Untangling that is what the phase 3 programme is for.

Note, preliminary or early findings are not the same as proof. Any use beyond a peptide’s FDA-approved labeling (where one exists) is described here for educational purposes only and is not a recommendation.

Safety

The side effect profile looks familiar if you have followed GLP-1 drugs, and for the same anatomical reason — the area postrema governs both appetite and nausea, so you rarely get one without risking the other.

Most common are gastrointestinal: nausea (typically transient and dose-dependent), vomiting, diarrhea, and constipation. Injection site reactions, including induration and redness, have been reported. Risk of low blood sugar is low when it is used without insulin.

Reasons to avoid it, or to talk to a clinician first:

• Personal or family history of medullary thyroid carcinoma
• Multiple endocrine neoplasia syndrome type 2 (MEN2)
• Pregnancy or breastfeeding
• Children under 18
• Known hypersensitivity to cagrilintide or any component

This is not a complete safety list. It is the set of things worth knowing before a conversation with a prescriber.

Questions worth bringing to a clinician

• How does cagrilintide compare to a GLP-1 like semaglutide for weight loss?
• What is the combination expected to add over either drug on its own?
• What gastrointestinal side effects should I expect, and how are they managed?

New research, translated

A quiet week. Both items below are real and newly indexed, and neither is a practice-changing result — we would rather say that than inflate them.

A mitochondrial peptide used as a delivery gel, not a drug

Bioactive Materials · MOTS-c · preclinical

Transplanting healthy mitochondria into damaged heart tissue is a real research avenue, and its main obstacle is mundane: isolated donor mitochondria fall apart quickly. This group bonded MOTS-c, the mitochondria-derived peptide, to a self-assembling peptide to build a gel that holds them together longer — picking MOTS-c specifically because of how it behaves around failing mitochondria. So it is doing double duty here, as both material and active ingredient. Worth noting mainly because MOTS-c reaches consumers on a very different premise: as an injection you take.

This is animal and bench work. It says nothing about taking MOTS-c.

Source ↗

A survodutide formulation study

ClinicalTrials.gov · survodutide · registered 2026-09-01

A bioequivalence trial was registered this month comparing survodutide delivered from a pre-filled syringe against the same drug from a vial, in healthy and overweight participants.

Nobody’s clinical decision changes on this. It is included because pre-filled syringe studies are the unglamorous paperwork that tends to precede a commercial launch, and survodutide is worth watching for that reason.

Source ↗

What we’re tracking

• A YC-backed startup selling personalized peptides and GLP-1s. RonanRX (YC S26) surfaced in our trend radar this week with a Launch HN post. We have no view on the company yet, but “personalized peptide” as a consumer category is exactly the kind of positioning that tends to run ahead of its evidence, and we will be reading the fine print.
• BPC-157, still the most-searched peptide we cover that has almost no completed human trials behind it.
• Compounding pharmacy activity, following July’s advisory committee vote.

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About cagrilintide (this peptide)

Cagrilintide is not in our regulatory database. It has not been evaluated or approved by the U.S. Food and Drug Administration for any medical use. Discuss with your healthcare provider before considering any substance not reviewed here.

Medical disclaimer

This letter is for educational and informational purposes only. It does not constitute medical advice, diagnosis, or treatment, and no provider-patient relationship is created by reading it. Peptides and medications discussed may not be FDA-approved for the uses described. Always consult your healthcare provider before making any health decision. Read our full medical disclaimer.