Petrelintide vs Cagrilintide: Comparing Two Investigational Amylin Analogs

Petrelintide and cagrilintide are both once-weekly amylin analogs being studied for weight loss, but they are different drugs from different companies at very different stages of development. Cagrilintide, from Novo Nordisk, is the more advanced candidate and is already in Phase 3 testing in combination with semaglutide. Petrelintide, from Zealand Pharma and Roche, is earlier in development and has reported encouraging early-stage weight loss data. Neither drug is FDA-approved, and neither can be prescribed in the United States today.

What Are Petrelintide and Cagrilintide?

Both compounds mimic amylin, a hormone the pancreas releases alongside insulin after a meal. Amylin slows stomach emptying and signals fullness to the brain, which is why amylin analogs can reduce appetite and food intake without working only through GLP-1 pathways.

Petrelintide is also known by its code name ZP8396. Zealand Pharma designed it to be highly soluble, which may make it easier to combine with other peptides in a single injection. Cagrilintide, formerly AM833, uses the same basic mechanism and is best known as the second half of CagriSema.

These are not the only amylin analogs in the pipeline. Anyone following the class quickly runs into eloralintide vs cagrilintide discussions, since Eli Lilly's eloralintide targets a similar receptor profile.

Petrelintide vs Cagrilintide at a Glance

Feature	Petrelintide (ZP8396)	Cagrilintide (AM833)
Developer	Zealand Pharma, with Roche	Novo Nordisk
Drug class	Long-acting amylin analog	Long-acting amylin analog
Route and schedule	Once-weekly subcutaneous injection	Once-weekly subcutaneous injection
Main combination strategy	Being paired with GLP-1 candidates	CagriSema (cagrilintide plus semaglutide)
Development stage	Phase 2b	Phase 3
Monotherapy weight loss reported	Up to about 8.6% at roughly 16 weeks in an early trial	About 10.8% at 48 weeks in a Phase 2 trial
Weight loss with a GLP-1	Not yet reported in late-stage trials	Low-20% range at 68 weeks with semaglutide
FDA approval status	Not approved	Not approved

One caveat matters here: these numbers come from trials with different designs, doses, durations, and patient populations. A small early-stage study cannot be lined up against a large Phase 3 program and treated as a fair fight.

Weight Loss Results Reported So Far

Reported results are the main reason people search for petrelintide vs cagrilintide comparisons.

• Petrelintide: In an early trial, participants on the highest dose lost up to roughly 8.6% of body weight over about 16 weeks, with side effects that investigators described as manageable.
• Cagrilintide alone: A Phase 2 study reported about 10.8% weight loss at 48 weeks with the 4.5 mg dose, well ahead of placebo.
• Cagrilintide plus semaglutide: Phase 3 CagriSema trials have reported weight reductions in the low-20% range at 68 weeks, among the largest results seen in an obesity drug program.

The overall pattern is consistent. Amylin analogs produce meaningful weight loss on their own, and they appear to add to what GLP-1 drugs already achieve.

Dosing, Delivery, and Trial Access

Both drugs are given as a once-weekly subcutaneous injection, similar to how semaglutide and tirzepatide are dosed. In studies, they arrive as finished, manufacturer-filled pens or prefilled devices rather than powders that patients measure themselves.

That distinction matters. People who handle research-grade peptides often ask about reconstitution solution vs bacteriostatic water for peptides, and the same group debates bac water vs sodium chloride. Those questions apply to lyophilized laboratory materials, not to the pens used in petrelintide and cagrilintide trials.

Cagrilintide studies are global and run at a later stage, so trial infrastructure is more established. Petrelintide remains in Phase 2b, which means fewer sites and tighter eligibility criteria for volunteers.

Side Effects and Safety Considerations

Because amylin analogs slow stomach emptying, gastrointestinal effects dominate the side effect profile.

• Nausea, usually worst during dose escalation
• Vomiting and diarrhea
• Constipation
• Reduced appetite and early fullness
• Injection site reactions

In CagriSema trials, a notable share of participants reported nausea, and gastrointestinal effects were a leading reason some people stopped treatment. Petrelintide's early data suggest a similar but possibly milder pattern, though those studies are too small to be definitive.

Amylin analogs also carry class-level cautions. Anyone with a history of pancreatitis, gastroparesis, or certain thyroid conditions should discuss risks with a healthcare professional before considering an investigational treatment. Long-term safety data for both drugs are still being collected.

How They Fit Into the Broader Weight Loss Landscape

Amylin analogs are being positioned as partners rather than replacements for GLP-1 drugs. That is why late-stage testing pairs cagrilintide with semaglutide instead of studying cagrilintide alone.

Comparisons with newer incretins are unavoidable. A common question is cagrilintide vs tirzepatide, which pits an amylin-plus-GLP-1 combination against a GLP-1/GIP dual agonist. Another is cagrilintide vs retatrutide, a triple agonist that targets GLP-1, GIP, and glucagon receptors at once.

For now, tirzepatide and semaglutide are the approved options, and retatrutide is still investigational. Petrelintide sits furthest back in this group, so its final efficacy and safety numbers carry the most uncertainty.

For patients, the practical takeaway is simple: neither petrelintide nor cagrilintide is available by prescription, and products sold online under those names are unverified and potentially unsafe. The only legitimate access today is through an enrolled clinical trial.

COMMON QUESTIONS

Frequently Asked Questions

Is petrelintide or cagrilintide FDA approved?

No. Neither petrelintide nor cagrilintide is FDA-approved for any indication in the United States. Cagrilintide is in Phase 3 trials as part of CagriSema, and petrelintide is in Phase 2b testing. Both are available only to participants in supervised clinical studies.

Which one causes more weight loss, petrelintide or cagrilintide?

There is no fair head-to-head answer yet. Cagrilintide has produced larger reported numbers, but it has been tested in longer, larger trials and in combination with semaglutide. Petrelintide's results come from smaller, shorter early-stage studies, so any direct comparison is speculative.

Can I get petrelintide or cagrilintide from a telehealth provider or compounding pharmacy?

No. Neither drug is approved, so it cannot be legally prescribed or compounded in the United States. Products marketed online as cagrilintide or petrelintide are unregulated, unverified, and potentially unsafe. The only legitimate access is enrollment in a clinical trial.