Petrelintide is an experimental once-a-week weight-loss injection from the Danish company Zealand Pharma, developed together with Roche. It copies amylin, a hormone your pancreas releases alongside insulin after a meal that helps tell your brain you've had enough. On September 22, 2026, Zealand said petrelintide had entered phase 3, the large final stage of testing that regulators rely on: three trials, about 7,000 adults, with the main measurement taken at week 64.
That's a real step, and it's a plan rather than a result. Petrelintide is not approved anywhere, and outside a clinical trial nobody can be prescribed it.
What Zealand announced: the petrelintide phase 3 program
The program is called ZUPREME. Zealand's September 22 release describes three trials. Each compares a weekly petrelintide shot with a placebo (a dummy injection), and neither the participants nor their doctors know who is getting which.
| Trial | Who takes part | Size |
|---|---|---|
| ZUPREME-3 | Overweight or obesity plus at least one weight-related condition, without type 2 diabetes | about 3,900 |
| ZUPREME-4 | Overweight or obesity with type 2 diabetes | about 600 |
| ZUPREME-5 | Overweight or obesity with established heart or blood-vessel disease, with or without type 2 diabetes | about 2,500 |
In all three, the dose is stepped up over 12 weeks and then held. The main question is plain: by what percentage has body weight changed at week 64? Waist size, blood sugar, other heart-risk markers, physical functioning and eating behaviour are measured too, and ZUPREME-5 can run for up to three years.
Zealand calls these registrational trials, meaning they are designed to support an application to regulators.
What petrelintide means if you take semaglutide or tirzepatide
For now, nothing changes. Petrelintide is given only to people enrolled in its trials, and none of the ZUPREME trials tests it against semaglutide or tirzepatide.
Semaglutide and tirzepatide are what a provider can weigh today. Through Promise, both are dispensed as compounded medications, which are different from an FDA-approved product: the formulations offered here are not FDA-approved. Compounded semaglutide explains what that preparation is and isn't. A licensed provider may still prescribe a compounded formulation where they judge it appropriate, and that decision is between you and your doctor.
How an amylin weight loss shot works
Your body has several ways of saying "that's enough." Semaglutide copies one of them, a gut hormone called GLP-1. Tirzepatide copies GLP-1 and a second gut hormone, GIP. Amylin is a separate signal. The body's own amylin slows how fast the stomach empties and acts in the brain to bring a meal to an end. What is cagrilintide covers amylin in more depth.
Petrelintide was built to last. In two small early trials published this year, its half-life (the time it takes the level in the blood to fall by half) was about 10 days, which is what makes a weekly shot workable, and 16 weeks of weekly doses brought weight loss of up to 8.6% (Brændholt Olsen et al., Diabetes, Obesity and Metabolism 2026).
One difference stands out. In those same early studies, petrelintide did not slow stomach emptying, even at the highest weekly dose tested, according to a conference abstract Zealand presented in June. The body's own amylin and GLP-1 medicines both do, though this was measured only in small groups of healthy volunteers.
Zealand's chemists also designed it to stay stable in a near-neutral solution, so it could one day share a pen with other peptide drugs (Fischer Munch et al., Journal of Medicinal Chemistry 2025).
Petrelintide results from phase 2
The phase 3 program rests on ZUPREME-1, a 42-week trial that enrolled 493 adults with overweight or obesity. They weighed about 107 kg (236 lb) on average, and 53% were women. In its March 5, 2026 release, Roche reported average weight loss of up to 10.7% by week 42 on the best-performing dose, against 1.7% on placebo.
That figure uses the "efficacy estimand": the result as if everyone had kept taking the drug as assigned, which usually reads a little better than counting everyone who started. Roche said the count-everyone figure was largely consistent in that group, and that women lost considerably more weight than men.
For scale, with a big caveat: in SURMOUNT-1, a 72-week trial of 2,539 adults, tirzepatide led to 15.0% to 20.9% average weight loss depending on dose, against 3.1% on placebo (Jastreboff et al., New England Journal of Medicine 2022). In STEP 1, a 68-week trial of 1,961 adults, semaglutide 2.4 mg led to 14.9% against 2.4% (Wilding et al., New England Journal of Medicine 2021). Those trials ran longer, enrolled different people and counted differently, so they can't be lined up against 10.7% directly. They do show the bar a newcomer is measured against.
Petrelintide side effects in phase 2
Zealand's own summary is "double-digit weight loss with a tolerability profile largely comparable to placebo," and the gut figures it presented at the American Diabetes Association meeting in June are why (Garvey et al., Diabetes 2026 abstract):
| ZUPREME-1 side effect | Petrelintide | Placebo |
|---|---|---|
| Nausea | 19.6% | 6.2% |
| Vomiting | 3.0% | 6.2% |
| Diarrhoea or constipation | under 7.5% | under 7.5% |
About one person in five on petrelintide reported nausea at some point, and 1.5% stopped the drug because of gut side effects.
As of September 23, 2026, the day this article was written, the phase 2 results had appeared only in company releases and a short conference abstract. Neither is a full peer-reviewed paper.
What the phase 3 start does not mean
It isn't a result. A trial start tells you what a company plans to measure. Each person in ZUPREME is treated for 64 weeks, roughly 15 months, before the main measurement, so the answers are more than a year away even for the first people enrolled.
It isn't a timeline to a pharmacy. Zealand has given no date for results or for an application.
It isn't something to add to what you take now. Amylin drugs are being studied alongside GLP-1-type medicines, and Novo Nordisk's CagriSema already pairs one with semaglutide in trials. Petrelintide can't be added to any prescription today.
It isn't a reason to shop online. Anything sold under the petrelintide name without a prescription, often labelled for laboratory use, is not the trial drug. There's no prescriber, no pharmacy of record, and nobody to call if the contents are wrong.
What to watch next
- ZUPREME-2. The second phase 2 trial, in 221 adults with type 2 diabetes, was completed on August 13, 2026, according to its registry record. Roche said in March that topline results were expected in the second half of 2026.
- The combination. A phase 2 trial called ZYNERGY will give petrelintide alongside enicepatide, Roche's experimental GLP-1/GIP drug, to about 486 adults. Its registry record lists an estimated start of September 30, 2026, with weight change at week 40 as the main measure.
- The full ZUPREME-1 paper. Zealand said in June that complete results would be published later this year.
- The rivals. Eli Lilly's amylin drug, eloralintide, is already in phase 3.
Where this leaves you today
Where petrelintide ends up will be settled by trials that have only just begun. If you're weighing a prescription now, the choice is between medicines that already exist, set against your medical history, your other medicines and how you've handled similar drugs before. At Promise, a licensed provider reviews every request and prescribes only when a medication is appropriate for you. Not everyone qualifies.