Petrelintide: The Definitive Guide

What is petrelintide?

Petrelintide is an experimental weight-loss medicine, given as a once-weekly injection, that copies amylin, a hormone that helps you feel full after eating. Zealand Pharma discovered it, and Roche now co-develops it. It is not approved anywhere, and its large phase 3 program was launched in September 2026. [1], [2]

Amylin is made by the pancreas and released together with insulin after meals, and it helps signal fullness to the brain. Natural amylin tends to clump into sticky strands, and the older amylin drug pramlintide is cleared so quickly that it has to be injected before every meal. Petrelintide is a lab-made amylin analogue: a chain of 35 amino acids based on the 37 of human amylin, with two removed, several others swapped, and a fatty-acid tail that keeps it in the blood for about 10 days. [3], [4], [5], [6]

The key word is investigational: it is still being tested, and no regulator has approved it. Unlike most peptides sold online, though, it has been tested in placebo-controlled trials with more than 600 participants. You may also see its development code ZP8396, or Roche's code RO7895515. It is not a GLP-1 drug like semaglutide or tirzepatide; it acts on amylin and calcitonin receptors instead. [6], [7], [8], [9]

People discuss it for two reasons. Its developers are betting on tolerability: they hope it will cause less nausea and vomiting than GLP-1 drugs, so more people can stay on it. And it was designed to mix with other injections, so it may one day be paired with an incretin drug such as Roche's enicepatide. [10], [3], [11]

Typical Petrelintide Protocols

The most-cited schedule in the reviewed sources is this phase 1 pattern: one subcutaneous dose a week, starting at 0.6 mg and raised every 2 weeks to a target of 2.4 or 4.8 mg (or from 1.0 mg to 9.0 mg), for 16 weeks. It is the only published petrelintide schedule with milligram dose steps, and most dosing websites copy it. (Phase 1 also tested fixed weekly doses of 0.6 or 1.2 mg for 6 weeks in lean men, described in the provenance note below.) The larger phase 2 trial, ZUPREME-1, raised the dose every 4 weeks instead, to one of five targets "up to 9 mg", and kept people on it until week 42. [6], [12], [13], [14], [15], [16]

Titration Raising the dose in steps

Every trial longer than 6 weeks has started low and stepped up. In the 16-week phase 1 trial, each step lasted 2 weeks, and investigators could hold a step for an extra week or lower the dose if side effects were a problem; only one person needed that (an extra week at 7.5 mg). ZUPREME-1 stepped up every 4 weeks, taking 4 to 16 weeks to reach the target, and 88–98% of people reached their assigned dose. The phase 3 trials use a 12-week climb. [6], [12], [7], [17], [1]

Breaks and cycles

Not established. Every trial gave petrelintide continuously: 16 weeks in phase 1, 42 weeks in phase 2 and 64 weeks planned in phase 3. No study has tested stopping and restarting, or planned breaks. [6], [7], [1]

Read the units: petrelintide amounts are written in milligrams (mg); 0.6 mg is the same as 600 mcg. Each number is the amount given once a week, so the weekly total and the amount each time are the same. The 9.0 mg target is about 15 times the 0.6 mg starting dose, which is why the trials climbed slowly.

Each row is a complete schedule from one trial group of 12 people. Low, mid and high are alternatives, not steps to move through. The 4.8 mg group lost slightly more weight than the 9.0 mg group, but the 9.0 mg group spent only 6 weeks at its target, which the authors note limits the comparison. These are research schedules, not an approved label; the cited references give the full details. [6]

Cautions before reading any petrelintide dose:

• The phase 2 and phase 3 doses are secret. The companies have published only that ZUPREME-1 used five target doses "up to 9 mg". The phase 1 targets of 2.4, 4.8 and 9.0 mg are not the same as ZUPREME-1's Dose 1 to Dose 5, and any website that prints a five-dose milligram table is guessing. [16], [7]
• No approved product exists outside trials. Vials sold online as "research use only" have not been checked by any regulator for identity, strength or sterility, and their concentration is whatever the seller says. [18], [19]
• Unit mistakes are easy at these amounts. The 9.0 mg target is nearly a whole 10 mg vial each week. Syringe units depend on how the powder was mixed.
• Some people have no published safety data. People with type 2 diabetes (a trial in 221 people finished in August 2026 but has not released results), anyone using insulin, pregnant or breastfeeding people and anyone under 18. See who should be especially cautious.

Where protocols differ: step speed, the missing phase 2 doses, website errors and combinations ↓

What is petrelintide commonly used for?

Petrelintide is being developed for one purpose: long-term weight management in adults with obesity, or with overweight plus a weight-related health problem. Outside trials, people ask about it because it promises weight loss with fewer stomach side effects than GLP-1 drugs, and as a possible partner for those drugs. [1], [8], [10]

The trials show that it lowers body weight more than placebo, with an average of about 9–11% at 42 weeks. They do not yet show how well it works over years, in people with diabetes, or combined with other drugs. [7], [25]

Weight loss

This is the only use tested in people. In ZUPREME-1, 485 adults without diabetes (average weight 107 kg, about 236 lb) took one of five doses or placebo for 42 weeks, alongside diet and exercise advice. Average weight loss was 8.7–10.7% on petrelintide, compared with 1.7% on placebo, if everyone kept taking their injections. The largest loss came with the middle dose, Dose 3. [7], [17]

Those are company-reported results from a conference and an investor presentation, not yet a peer-reviewed paper. The trial's main result, at week 28, has not been published as numbers. [7], [10]

Doserly

How much weight did people lose on petrelintide?

Average percentage change in body weight from the start of the trial.

Phase 1 · 16 weeks · 48 adults with overweight or obesity · 12 per group · 2-week dose steps

observed averages.
Placebo −1.7%
Target 2.4 mg −4.8%
Target 4.8 mg −8.6%
Target 9.0 mg −8.3%
Separate groups, not steps: each target was a different set of 12 people. The 9.0 mg group spent only 6 weeks at its target.

ZUPREME-1 phase 2 · 42 weeks · 485 adults without diabetes · 4-week dose steps · doses not disclosed

efficacy estimand (if everyone had stayed on treatment).
Placebo (n=81) −1.7%
Dose 1 (n=79) −8.7%
Dose 2 (n=81) −9.2%
Dose 3 (n=83) −10.7%
Dose 4 (n=79) −10.5%
Dose 5 (n=82) −10.2%
Company-reported conference data; milligram amounts for Doses 1 to 5 have not been published (upper bound 9 mg).

Separate trials: the phase 1 groups and ZUPREME-1 doses are not one dose ladder.

Is it gentler on the stomach than GLP-1 drugs?

Not proven, although this is the main reason petrelintide gets attention. Against placebo in ZUPREME-1, vomiting was less common overall (3.0% vs 6.2%), fewer people on petrelintide stopped treatment for any reason, and stopping because of side effects was about the same as on placebo (4.5% vs 4.9%). Nausea, though, was three times as common as on placebo (19.6% vs 6.2%), mostly mild and mostly while the dose was going up. [7], [17]

No trial has compared petrelintide with a GLP-1 drug directly, so "gentler than GLP-1 drugs" rests on comparisons across separate trials in different people. The risks section has the full side-effect table. [6]

Appetite and "food noise"

Amylin is a fullness signal, and in the trials "decreased appetite" was one of the most common reported effects: 58–83% of people in the 16-week phase 1 groups, versus 42% on placebo. In rats, petrelintide cut food intake mainly by reducing high-fat food. Whether it quiets intrusive thoughts about food, often called food noise, has not been measured. [6], [26]

As a partner for GLP-1-type drugs

Petrelintide was designed to stay stable at a near-neutral pH, which lets it be mixed in one solution with other peptide drugs. In rats it added to the effect of semaglutide and tirzepatide. Roche plans a phase 2 trial, ZYNERGY, of petrelintide with its own GLP-1 and GIP drug enicepatide, but it had not started recruiting by September 2026, so no human combination data exist. [3], [27], [28], [11]

Heart and metabolic markers

ZUPREME-1 also reported smaller waists (7.9–10.8 cm, versus 4.3 cm on placebo) and falls in hsCRP, a blood marker of inflammation (17–41% versus 6%), and in triglycerides, a type of blood fat (12–21% versus 9%). Blood pressure, blood sugar and heart outcomes have not been reported, and the people studied did not have diabetes. [7], [17]

Other claims you may come across

Claims that petrelintide "preserves muscle" or "restores leptin sensitivity" go beyond the evidence. The muscle claim rests on a rat study that expressed lean mass as a share of body weight, and the phase 2 body-composition scans have not been reported. The leptin claim comes from older studies of amylin and pramlintide in rats and people, not from petrelintide itself. [29], [30], [31]

See the full trial results or how it works.

Where do petrelintide protocols differ?

The trials themselves are consistent: one dose a week, started low and raised in steps. The disagreements come from what has not been published, and from websites filling the gaps.

Why is there no public phase 2 dose?

Because the companies have not released it. ZUPREME-1 tested five doses, called Dose 1 to Dose 5 in every public presentation, and Zealand has said only that the five targets went "up to 9 mg". Each dose group had its own volume-matched placebo, so participants and investigators knew which dose level someone was on but not whether it was petrelintide or placebo. [16], [7], [8]

That leaves the phase 1 amounts as the only published milligram doses. They should not be matched to ZUPREME-1's dose groups: phase 1 had three targets, phase 2 had five, and the step speed was different. [6], [7]

Is 4.8 mg a starting dose, or the top dose?

Neither. In phase 1, 4.8 mg was the target for one group, reached after 8 weeks of steps from 0.6 mg, and a separate group went up to 9.0 mg. Some pages get this wrong: one calculator calls 4.8 mg "a common starting dose", and several protocol pages from the same publisher call it the highest dose tested, leaving out the 9.0 mg group. [6], [32], [33], [34], [35]

Doserly

How did the trials raise the dose?

Target 2.4 mg

0.6 mg in weeks 1–2, 1.2 mg in weeks 3–4, then 2.4 mg from week 5 to 16.

Target 4.8 mg

0.6 mg in weeks 1–2, 1.2 mg in weeks 3–4, 2.4 mg in weeks 5–6, 3.6 mg in weeks 7–8, then 4.8 mg from week 9 to 16.

Target 9.0 mg

1.0 mg in weeks 1–2, 2.0 mg in weeks 3–4, 4.0 mg in weeks 5–6, 6.0 mg in weeks 7–8, 7.5 mg in weeks 9–10, then 9.0 mg from week 11 to 16; doses above 4.8 mg given as two or three injections at the same visit.

ZUPREME-1

Five groups raised every 4 weeks for 4 to 16 weeks to targets up to 9 mg (amounts not published), then held to week 42; 9 weeks off drug to week 51.

Phase 3

12-week climb, then maintenance; main result at week 64. ZUPREME-3 and -4 end at week 77; ZUPREME-5 continues for up to about 3 years.

Phase 1 doses are published; ZUPREME-1 and phase 3 amounts are not.

Every 2 weeks, or every 4?

The trials used three speeds. Phase 1 stepped up every 2 weeks. ZUPREME-1 stepped up every 4 weeks, taking up to 16 weeks to reach the highest targets. Phase 3 uses a 12-week climb. Websites range from every 2 to 4 weeks to no stated interval. [6], [7], [1], [13], [24]

Roche and Zealand credit the slower phase 2 steps for the milder stomach side effects seen in ZUPREME-1. That is a reasonable explanation, but it compares two different trials; no study has tested fast against slow steps directly. In phase 1, nausea and vomiting after single doses appeared only at the two highest amounts (1.4 and 2.4 mg), which fits the idea that big jumps are harder to tolerate. [10], [6]

Where do 0.3 mg, 250 mcg and "2.4 mg weekly" come from?

Not from petrelintide trials. A few website numbers have no source behind them:

The same pages repeat factual errors. One describes petrelintide as "pegylated" with an 8-day half-life, another gives a 20-minute half-life, and a third names a different compound code (ZP6590) and a combination trial we could not find. The measured half-life in people is about 10 days, and the molecule carries a fatty-acid tail, not a PEG chain. [23], [36], [37], [6], [5]

One injection, or several?

Once weekly in every trial. At the highest phase 1 doses, the weekly amount was split into two or three injections given at the same visit, because each injection was limited to 1 mL. That is a volume limit, not a split across the week. No study has tested dividing the weekly dose over several days. [6], [38]

How long, and are breaks needed?

The trials ran continuously: 16 weeks in phase 1, 42 weeks in ZUPREME-1, and 64 weeks planned in phase 3, with the phase 3 trial in people with heart or blood-vessel disease able to run up to about 3 years. Websites disagree: one calls use "ongoing and repeatable", another suggests a washout and review before repeating a course, and a third correctly notes that the trials did not cycle it. No trial has compared breaks with continuous use. [6], [7], [1], [34], [23], [15]

Can petrelintide be combined with semaglutide, tirzepatide or another amylin drug?

Not on the evidence so far. No human study of petrelintide with any other drug has reported results. The only planned human combination is Roche's ZYNERGY trial with enicepatide, which had not started recruiting in September 2026. In rats, petrelintide added to the effects of semaglutide and tirzepatide, and it stayed stable when mixed with semaglutide in one solution. [11], [39], [27], [28], [3]

Adding it to cagrilintide or eloralintide would double up the same amylin mechanism, and community education groups teach against stacking two amylin drugs for that reason. No blend containing petrelintide has been tested in people.

How do milligrams convert to syringe units?

Petrelintide sold online usually comes as a freeze-dried powder, often 5 or 10 mg per vial, that is mixed with sterile water. Syringe units on an insulin syringe measure volume, not an amount of petrelintide, so the dose in each unit depends on how much water was added. [13], [32], [40]

For example, 10 mg mixed into 2 mL gives 5 mg per mL, so 0.6 mg is 0.12 mL, or 12 units on a U-100 syringe. The same 10 mg mixed into 1 mL gives 10 mg per mL, so 0.6 mg is 6 units and 4.8 mg is 48 units. At the 9.0 mg target, one 10 mg vial would hold barely more than a single weekly dose. Mixing up "units" and "milligrams" can multiply a dose many times over. Doserly's reconstitution calculator works out the arithmetic for any vial and shows each step. [13], [15]

What happens when you stop petrelintide?

Nobody knows yet for petrelintide itself. No trial has published what happens to weight or appetite after the last dose. [30], [7]

• The follow-up period. ZUPREME-1 continued for 9 weeks after the last injection (weeks 42 to 51), but that period was used to collect side-effect information, and no weight results from it have been released. [7], [30]
• How long it stays in the body. With a half-life of about 10 days, petrelintide leaves the body slowly: roughly half is gone after 10 days, and only about 3% remains after 50 days (five half-lives). The phase 1 trial kept measuring blood levels for up to 9 weeks after the last dose. [6]
• Rebound or withdrawal effects. None have been described, but no study was designed to look for them.

Other weight-loss drugs give some idea of what to ask about. After people stopped semaglutide in the STEP 1 trial extension, they regained about two-thirds of the weight they had lost within a year. That is a GLP-1 drug, not an amylin drug; whether weight lost on petrelintide returns the same way has not been tested. We found no study comparing tapering down with stopping all at once. [41]

How is petrelintide taken, and how long does it last?

Petrelintide is taken only by subcutaneous injection (into the fatty layer under the skin), once a week. In phase 1, injections went into a lifted fold of skin on the belly; in ZUPREME-1, participants injected themselves using a vial and syringe. One small phase 1 group received a single intravenous dose (IV, into a vein) only to measure absorption. No pill, nasal spray or cream form has been tested. [6], [8]

In people, petrelintide is absorbed slowly and lasts a long time. In the weekly-dose trial, blood levels rose most in the first 12–24 hours after each injection and then stayed on a long plateau until about day 6. Its measured half-life, the time for blood levels to fall by half, averaged 213–257 hours (about 9 to 11 days). About 77% of an injected dose reached the bloodstream compared with the IV dose, a measure called bioavailability. Levels leveled off after about five weekly doses and rose in proportion to the dose from 0.6 to 9.0 mg. [6]

That long half-life is why weekly dosing works, and it has practical consequences. Levels build up over the first month, a missed dose does not drop levels to zero, and an accidental extra dose takes weeks to clear. The fatty-acid tail is what makes this possible; in rats the half-life was about 34 hours, far shorter than in people. [6], [3]

Do kidney or liver problems change the dose?

Unknown. A single-dose study in people with reduced kidney function finished in November 2025, and a liver-function study was still recruiting in September 2026; neither has published results. [51], [52]

Is a vial sold online the same as the trial product?

No. Trial participants received a manufactured solution with a known strength, and a 2026 study compared four concentrations of the company's product without naming them. Online products are usually powders sold as "research use only", with no approved label, no verified content and no instructions for people. [6], [53], [18]

How should petrelintide be stored, and how long does it last?

There is no approved label with storage instructions. The public record shows only this much:

• The trial product. Phase 1 used a ready-made solution in vials, and ZUPREME-1 used vials and syringes. Its concentration, storage temperature and use-by period have not been published. [6], [8], [53]
• The molecule. Petrelintide was designed to stay stable in liquid near neutral pH. In laboratory tests, solutions of 1 to 10 mg per mL formed no fibrils and almost no clumped (oligomer) forms after up to a month at 40 °C, a stress test used to predict stability. That was a design result, not a use-by date for any product. [3]
• Powder sold online. These are unverified website claims, not tested instructions. One protocol website says the unmixed powder keeps frozen at −20 °C and that the mixed (reconstituted) solution keeps in the fridge at 2–8 °C for about 4 weeks; a calculator says 28 days; another page admits storage is undisclosed and assumes refrigeration. None cites a stability test of a mixed petrelintide vial, so how long one stays usable is not established. [13], [32], [33]

This guide does not cover mixing or injection technique; the Academy note below points to practical handling.

What do we actually know about petrelintide in people?

More than for most peptides, less than for approved weight-loss drugs. There is one peer-reviewed human paper, covering two phase 1 trials with 132 people dosed for up to 16 weeks. The larger phase 2 trial, with 485 people treated for 42 weeks, has so far been reported only in company announcements, an investor presentation and a conference abstract. [6], [7], [54]

What did the trials find?

What did ZUPREME-1 show dose by dose?

All five doses beat placebo at week 28, the trial's main time point, and at week 42. The results do not climb steadily with dose: Dose 3 did best, and Doses 3, 4 and 5 ended close together. [7], [10]

Source: Roche's June 2026 presentation of data from the American Diabetes Association's 2026 conference. [7]

People started at an average of 107 kg (about 236 lb) and a BMI of about 37, so a 10% loss is roughly 10.7 kg (about 24 lb). Roche reported that 98% of people in the best-performing group reached their target dose and that women lost considerably more weight than men, but it has not released the numbers by sex. [17], [10]

Why is only one kind of result published?

Trials often report two versions of the same result, called estimands. The "efficacy" number, used for every ZUPREME-1 figure above, estimates what would have happened if everyone had kept taking their injections. The "treatment-policy" number counts everyone as randomized, including people who stopped. Roche says the treatment-policy results were "largely consistent", but it has not released them. [7], [10]

This matters because stopping was common in both groups: by week 42, 15.5% of people on petrelintide (9.6–18.3% across doses) and 24.7% on placebo had stopped treatment for any reason. [7]

Does it work differently in women and men?

Possibly. In a later analysis of the phase 1 trial, women tended to lose more weight than men, though only about one in five participants was a woman. Roche said the same of ZUPREME-1, which was 53% women, without giving the numbers. Neither result settles the question. [38], [10], [17]

What would a useful result look like in everyday life?

A trial average is not a prediction for one person, and ZUPREME-1 has not published how many people lost at least 5%, 10% or 15%. A useful result might mean steady weight change while still eating enough protein and fluid, nausea that settles once the dose stops rising, and a smaller waist. [30]

That is why it helps to track more than weight. Appetite, energy, stomach symptoms and hair shedding can move in different directions.

What don't the trials tell us?

• The phase 2 doses. The milligram amount in each ZUPREME-1 group has not been published. [7]
• People with type 2 diabetes. ZUPREME-2 finished in August 2026 without published results; ZUPREME-1 excluded diabetes. [25], [8]
• Use beyond 42 weeks. The phase 3 program, with trials of 64 weeks and longer, was launched only in September 2026. [1]
• What happens after stopping. No off-treatment weight data have been released. [30]
• Muscle and body composition. ZUPREME-1 scanned body composition by MRI, but the results have not been reported. [30], [16]
• Who was studied. Phase 1 was mostly men at one German clinic; ZUPREME-1 ran at sites in the United States, Poland and Romania. [6], [8]
• Independent research. Every human study so far was sponsored and largely written by the developers. [6], [54]

How does petrelintide work?

Petrelintide copies amylin, one of the body's "you've eaten enough" signals, but lasts far longer. Its receptor activity comes from cell studies and its effects on eating from rats; the weight loss itself is established in human trials.

Which receptors does it switch on?

In cell studies, petrelintide strongly activates amylin receptors, including the types called AMY1 and AMY3, and the calcitonin receptor, with potency similar to natural amylin. Each amylin receptor is the calcitonin receptor paired with a smaller partner protein. An agonist is a molecule that switches a receptor on, so petrelintide is an amylin and calcitonin receptor agonist. It was not designed to act on GLP-1 or GIP receptors, and no activity there has been reported. [6], [3]

Some websites call it a "balanced" amylin and calcitonin receptor agonist, a phrase from company slides. The published data show it acts on both; how much each receptor contributes to weight loss in people is not known. [7], [3]

Where in the body does it act?

For amylin drugs in general, the main target is the hindbrain, especially the area postrema, a small region on the back of the brainstem that helps control fullness. That is class physiology from earlier amylin research; we found no published study mapping where petrelintide itself acts in the brain. [6], [3]

Does it slow digestion?

Apparently not, which sets it apart from what is usually taught about amylin. Natural amylin and the older drug pramlintide slow gastric emptying, the speed at which food leaves the stomach. In a company conference abstract analysing the phase 1 trials, petrelintide did not measurably slow gastric emptying, judged by how quickly a swallowed dose of acetaminophen (paracetamol) reached the blood after a meal, either after single doses or at steady state with weekly doses up to 9.0 mg. That is an abstract, not a full paper, and the method measures emptying indirectly. A similar test found no delay with CagriSema. [57], [4], [6], [58]

How does it reduce eating?

In rats, petrelintide reduced food intake and body weight in proportion to the dose, and in one company study it cut intake mainly by reducing high-fat food rather than the standard diet. A 2026 abstract reported that rats on petrelintide ate less during their usual resting period than rats on semaglutide. How these patterns translate to people has not been studied. [3], [26], [59]

Why is it described as a partner for GLP-1 drugs?

Amylin drugs and GLP-1 drugs act on different receptors, so their effects can add up. That is the idea behind CagriSema, which combines cagrilintide with semaglutide and produced more weight loss than either drug alone in a large trial. Petrelintide was built to be mixed with other peptides in one solution, and in rats it added to semaglutide and tirzepatide. Whether that carries over to people is what the ZYNERGY trial will test. [60], [3], [27], [28], [11]

Does it preserve muscle or restore leptin sensitivity?

Neither has been shown in people. Any large weight loss includes some lean tissue (muscle, organs and water) as well as fat. In a 30-day study of obese rats, petrelintide reduced fat mass while lean mass stayed stable as a share of body weight; ZUPREME-1's body-composition results are still unpublished. The leptin claim comes from a 2008 study of amylin and pramlintide in rats and people, not from petrelintide. [29], [30], [31]

What are the risks and unanswered questions?

Is petrelintide safe?

It was generally well tolerated in trials lasting up to 42 weeks, but it is not approved, and its long-term safety is not established. Those data also describe a manufactured product given under medical supervision, not powders bought online. [7], [6]

The pattern so far is familiar for a weight-loss injection: nausea while the dose is going up, some bowel changes and injection-site reactions, and fatigue. One unexpected finding, more hair loss than on placebo, needs watching. About 500 people have received petrelintide in the published and company-reported trials, too few to rule out rare problems. [7], [6]

What side effects did the trials find?

The clearest data come from ZUPREME-1, where 404 people took one of five doses and 81 took placebo, with side effects collected until week 51. [7]

Source: Roche's June 2026 presentation of data from the American Diabetes Association's 2026 conference. [7]

About 77% of stomach and bowel side effects were mild, and most happened while the dose was going up. The highest dose had the most nausea (28.0%) and vomiting (8.5%). The often-repeated line "no vomiting" describes Dose 3, the best-performing group (Dose 2 also had none), not the trial as a whole. [7], [10]

In the 16-week phase 1 trial, stomach and bowel symptoms affected about half of people on both petrelintide and placebo. Nausea affected 17–33% of people on petrelintide versus 17% on placebo, constipation reached 25% in the 9.0 mg group, and only one person vomited, who then stopped treatment. There were no serious or severe side effects, and no liver, pancreas or gallbladder events. [6]

Why did more people lose hair?

Hair loss was reported in 4.7% of people on petrelintide versus 1.2% on placebo, and in 10.1% of the Dose 4 group. It did not rise steadily with dose (Dose 5 was 4.9%), and the companies have not explained it. It comes from one trial's side-effect table, so it cannot show whether petrelintide caused it. It is worth watching in the phase 3 trials. [7]

What about heart rate, blood sugar and antibodies?

• Heart rate. In phase 1, average pulse fell by about 5 beats per minute during weekly dosing. The authors note that other long-acting amylin drugs do the same. ECGs, blood pressure and laboratory tests showed no clinically important changes. [6]
• Blood sugar. In people without diabetes, HbA1c stayed at about 5.5% and no low-blood-sugar problems were reported. Petrelintide has not been studied with insulin; the older amylin drug pramlintide carries a boxed warning for severe low blood sugar when used with insulin. ZUPREME-2 measured low-blood-sugar episodes in type 2 diabetes, but its results are not yet out. [6], [4], [25]
• Antibodies. No one in the phase 1 trials developed anti-drug antibodies. ZUPREME-1 has not reported antibody results. [6], [22]

What problems do people report outside trials?

None, so far. We found no public or community account of someone using petrelintide outside a trial, and so no reports of side effects, dosing errors or product problems. That reflects how little it is used, not proof that it is safe. [61], [62]

Could product quality change the risk?

Yes. A correctly made trial drug and a vial bought online are separate questions. Any petrelintide sold to consumers comes from unregulated suppliers, and regulators warn that with unapproved peptides the biggest risk is not knowing what is in the vial: the wrong substance, the wrong amount, or contamination from non-sterile manufacturing. We found no regulator warning that names petrelintide itself as of September 24, 2026. [18], [19], [63]

Is petrelintide legal? Is it FDA-approved?

Checked September 24, 2026. Rules differ by country and change quickly.

United States. Petrelintide is not an FDA-approved medicine, and FDA's drug-approval and product-listing databases show no petrelintide application or product. It has an FDA substance identifier (UNII), which records the chemical and is not an approval. It is not on either list of bulk ingredients that pharmacies may use for compounding. FDA has said plainly that the amylin drug cagrilintide and retatrutide cannot be compounded under federal law; its page does not name petrelintide, but by the same rules petrelintide, which is unapproved and on neither list, does not qualify either. [64], [65], [66], [67], [68], [69]

Canada. No petrelintide product is authorized for sale. Health Canada has authorized two of the phase 3 trials and the ZYNERGY trial, which is permission to run a study, not to sell a drug, and in April 2026 it warned consumers not to inject peptides bought online. [70], [9], [50], [39], [19]

Australia. As an investigational drug, petrelintide has no Australian approval, and it is not named in the June 2026 Poisons Standard. In April 2026 the regulator, TGA, said that a "research use only" disclaimer does not make supplying a peptide lawful, and in May 2026 it warned consumers about importing unapproved peptide products. [71], [72], [18]

Europe and the United Kingdom. No petrelintide medicine is authorized by the European Medicines Agency. The UK regulator, MHRA, warns that weight-loss medicines must be licensed before they are sold or promoted, and that buying them from unregulated online sellers is risky. [73], [74], [63]

A "research use only" label does not make a product legal to sell for human use, and it does not make it safe.

Is petrelintide banned in sport? Does it show up on a drug test?

Petrelintide is not named on the World Anti-Doping Agency's 2026 Prohibited List or on the 2027 list that takes effect on January 1, 2027. However, WADA's category S0 bans, at all times, any drug with no current approval by a government health authority for human use, including drugs still in clinical development, and petrelintide has none. Tested athletes should treat it as prohibited. It is not on WADA's 2027 monitoring list, and none of the sources we reviewed describes a test method for detecting it. [75], [76], [77]

Who should be especially cautious?

These groups have little or no safety data. That is a reason for caution, not proof of harm.

• Pregnancy and breastfeeding. No data. ZUPREME-1 excluded pregnant and breastfeeding women and required effective contraception, and the phase 1 trials enrolled only women who could not become pregnant. [8], [6]
• People with diabetes, especially on insulin or sulfonylureas. No published results. ZUPREME-2 tested petrelintide in 221 adults with type 2 diabetes and finished in August 2026, but its results are not yet out. Amylin drugs can add to the blood-sugar-lowering effect of insulin. [25], [4]
• A history of pancreatitis. People with past or current pancreatitis were excluded from ZUPREME-1. [8]
• A history of eating disorders or low body weight. The weight-loss trials enrolled people with overweight or obesity; strong appetite suppression can make it hard to eat enough. [6], [8]
• Kidney or liver disease. Studies are under way, without results. [51], [52]
• People already on another weight-loss drug. ZUPREME-1 excluded anyone who had used weight-loss medicines in the previous 6 months, so no combination has been tested. [8]
• Upcoming surgery or procedures. Tell the surgical and anesthesia team about every weight-loss injection, including products bought online.
• Under 18. Not studied. This guide is written for adults.
• Competitive athletes. Covered by WADA's ban on unapproved substances. [75]

Does petrelintide interact with other medicines?

No interaction studies have been published. Two points are worth knowing. Pramlintide, the older amylin drug, slows stomach emptying, and its label warns about the timing of some tablets; petrelintide did not measurably slow stomach emptying in a phase 1 analysis, but that does not replace an interaction study. And any amylin drug taken with insulin raises the risk of low blood sugar. Bring a complete list of everything you take, including other peptides, to a pharmacist or doctor. [4], [57]

What should be monitored while using petrelintide?

There is no official monitoring plan, because petrelintide is not an approved medicine and has no prescribing label. What exists is a record of what the trials checked, which shows what researchers were watching for. It can help you prepare questions for a clinician; it is not a personal testing plan. [6], [8]

What did the trials check?

• Weight and related measures. Body weight and waist size, plus blood markers of heart and metabolic risk such as hsCRP and triglycerides. ZUPREME-1 also measured body composition with MRI scans, results not yet released. [7], [30], [16]
• Safety checks. The phase 1 trials recorded side effects and looked specifically for signs of liver injury, pancreas disease and gallbladder disease. They also ran laboratory safety tests, vital signs (including pulse), ECGs, physical and neurological examinations, checks of injection sites, and tests for antibodies to the drug. [6]
• Before entry. ZUPREME-1 screened out people with uncontrolled thyroid disease (using a thyroid blood test), diabetes and past pancreatitis. [8]
• In people with type 2 diabetes. ZUPREME-2 recorded severe or clinically significant low-blood-sugar episodes and antibodies to the drug; those results have not been released. [25]

Which signals matter, and why?

[7], [6], [8], [25]

Anyone taking petrelintide alongside a GLP-1 medicine such as semaglutide is also covered by that medicine's label, which has its own checks, including symptoms of pancreatitis and gallbladder disease, low blood sugar with insulin, and heart rate. Which checks make sense for you is a question for a clinician. [78]

What do people in public communities report?

Almost nothing first-hand. Petrelintide is not approved for sale, and it has not caught on with people who buy research peptides online, so public discussion is mostly about trial results, share prices and how it compares with other amylin drugs. We found no public account of anyone using it outside a trial. [79], [62], [80]

What do people who took it say?

We found no clear first-hand account. The closest was a July 2025 comment in a cagrilintide discussion from someone who said they were "finishing a trial", thought cagrilintide was "the closest thing to it" and was "Very happy w results". The comment does not name petrelintide or give a dose, and trial participants are not told whether they received the drug or placebo, so it cannot tell us much. [81]

What claims circulate, and how do they hold up?

What do community education groups teach?

In community education groups, petrelintide is presented as the gentler, lower-ceiling amylin drug and a likely future partner for incretin drugs. We found no members reporting that they had used it. Some teaching materials go further than the data, describing its stomach side effects as no worse than placebo or its absorption as about 85%; the published figures are nausea in 19.6% versus 6.2% on placebo, and 77% bioavailability. [7], [6]

How can you judge a weight-loss story?

Useful questions to ask: Was it petrelintide at all, or another amylin drug? Was the person in a trial, and could they have been on placebo? What dose, and was it measured in milligrams or syringe units? Were they also taking a GLP-1 drug, eating much less or exercising more? What happened after stopping?

Selected discussions help identify experiences and questions that research should examine. They are not a survey of all users, a response rate or a substitute for the controlled trials described above.

How does petrelintide compare with cagrilintide, zenagamtide and semaglutide?

These are the medicines most often weighed against petrelintide. Petrelintide and cagrilintide are long-acting amylin analogues, semaglutide copies the gut hormone GLP-1, and zenagamtide is a single molecule that acts on both GLP-1 and amylin receptors. Status was checked on September 24, 2026.

The weight results come from separate trials of different lengths in different people, and they count people who stopped treatment in different ways, so the table cannot rank these medicines. No trial has compared petrelintide with any of them. Two other amylin drugs come up in the same discussions: pramlintide (Symlin), approved in the United States in 2005 for diabetes and injected before meals alongside insulin, and eloralintide, an experimental once-weekly injection from Eli Lilly, with up to about 20% average weight loss at 48 weeks versus 0.4% on placebo in a phase 2 trial. The difference petrelintide's developers point to is tolerability, not the size of the weight loss, and that too can only be tested head to head. [4], [3], [88], [10]

Common questions about petrelintide

Is petrelintide a GLP-1 drug?

No. Petrelintide is an amylin analogue: it was built to act on amylin and calcitonin receptors, not on the GLP-1 or GIP receptors that semaglutide and tirzepatide target. Both kinds of drug reduce appetite, which is why they are often discussed together and why companies are testing them in combination. [6], [3] See how it works.

What dose of petrelintide was used in trials?

The published doses come from phase 1: one dose a week, started at 0.6 or 1.0 mg and raised every 2 weeks to 2.4, 4.8 or 9.0 mg over 16 weeks, plus a shorter test of fixed 0.6 or 1.2 mg doses for 6 weeks. The phase 2 trial ZUPREME-1 used five doses "up to 9 mg", raised every 4 weeks, but the amount in each group has not been published, and the phase 3 doses are also undisclosed. [6], [16] See typical protocols.

How long does petrelintide take to work?

Weight loss starts within weeks and builds over months. In phase 1, fixed weekly doses of 0.6 or 1.2 mg led to about 5% average weight loss after 6 weeks. In ZUPREME-1, average losses reached 8.7–10.7% at 42 weeks, and Zealand reported that weight was still falling at that point. Because its half-life is about 10 days, blood levels take about five weekly doses to level off. [22], [7], [30], [6] See the trial results.

When will petrelintide be available?

Not soon. Zealand announced the start of the phase 3 program on September 22, 2026, and its main result is measured at week 64. Companies usually apply for approval only after results like these, and no application or date has been announced. Until then, petrelintide is available only inside clinical trials. [1] See legal status.

Is petrelintide better than cagrilintide or eloralintide?

No one knows, because no trial has compared them directly. Their published weight losses come from trials of different lengths and designs, and petrelintide's developers are aiming at tolerability rather than the largest weight loss. [7], [60], [88] See the comparison table.

Does petrelintide cause hair loss?

It might. In ZUPREME-1, hair loss was reported by 4.7% of people on petrelintide and 1.2% on placebo, and by 10.1% in one dose group. The companies have not explained it, and a single trial cannot show cause and effect. [7] See the side-effect table.

Is it legal to buy petrelintide?

No approved product exists anywhere, so it cannot be bought as a medicine; outside trials, the only products on offer are unapproved vials. Products sold online as "research use only" are unapproved, and regulators in the United States, Canada, Australia and the United Kingdom warn against buying unapproved peptides or weight-loss medicines online. [64], [19], [72], [63] See the dated legal-status summary.

What happens when you stop petrelintide?

It is not known. No trial has published weight or appetite results after the last dose. With a half-life of about 10 days, the drug takes several weeks to leave the body. [30], [6] See what happens when you stop for the trial follow-up and what another weight-loss drug shows.

Glossary

Plain explanations of the route, dosing and research terms used in this guide. Underlined terms in the text link here.

Adverse event

A harmful or unwanted medical event reported after someone used a treatment. A report alone does not prove the treatment caused it.

Alopecia

The medical term for hair loss or thinning. In trials it is counted as a side effect whether or not the drug caused it.

Amino acid

A small chemical building block. Chains of amino acids make up peptides and proteins.

Amylin

A hormone released by the pancreas together with insulin after meals. It helps signal fullness to the brain.

Amylin analogue

A lab-made molecule designed to act like amylin. Petrelintide, cagrilintide and pramlintide are examples.

Animal study

Research in animals such as rats or mice. It shows what a substance does in a living body, but results in people can differ.

Anti-drug antibodies

Antibodies the immune system makes against a medicine. Some have no noticeable effect; others can reduce how well the medicine works.

Bioavailability

The share of a dose that reaches the bloodstream. For injected petrelintide it was about 77%, compared with an injection into a vein.

BMI (body mass index)

Weight in kilograms divided by height in meters squared. A BMI of 30 or more is classed as obesity, and 25 to 29.9 as overweight.

Amylin and calcitonin receptors

Switches on cells that respond to amylin and to calcitonin, a hormone involved in calcium balance. Each amylin receptor is the calcitonin receptor paired with a partner protein. Petrelintide activates both kinds.

Cell study (in vitro)

Research on cells grown in a dish. It gives early clues about biology, but it is far from proof of benefit in people.

Compounding

When a pharmacy prepares a customized medicine from individual ingredients. In the US, federal rules control which bulk ingredients pharmacies may use.

Controlled trial

A study that compares people who receive a treatment with a similar group who do not, often receiving a placebo instead. Randomly assigning people to each group makes the comparison fairer.

Course and cycle

A course is the period of repeated use, such as 16 weeks. A cycle is a course plus a planned break before any further use.

Dose (amount each time)

The amount given on one occasion. A protocol lists both the dose and how often it is given.

ECG

Electrocardiogram, a recording of the heart's electrical activity taken with sensors on the skin. It shows heart rate and rhythm.

Estimand

The exact question a trial result answers. An efficacy result estimates what happens if everyone keeps taking the drug; a treatment-policy result counts everyone as assigned, including people who stopped.

Food noise

An informal term for frequent, intrusive thoughts about food and eating. It is not a medical measurement.

Freeze-dried (lyophilized)

A powder made by freezing a solution and removing the water. Peptides sold online usually come this way and must be mixed with sterile water before injection.

Gastric emptying

How quickly food leaves the stomach. Slower emptying can make people feel full sooner and can change how fast some tablets are absorbed.

GLP-1 drugs

Medicines such as semaglutide that act on the GLP-1 receptor to reduce appetite and lower blood sugar. Tirzepatide and retatrutide also act on other hormone receptors. Petrelintide is not a GLP-1 drug.

Half-life

The time it takes for the measured level of a substance in the blood to fall by half. It is not the same as how long an effect lasts.

hsCRP

High-sensitivity C-reactive protein, a blood test for low-level inflammation. Higher levels are linked with heart and blood-vessel risk.

Intravenous (IV)

Given directly into a vein. Petrelintide was given this way only once, in a phase 1 test of how much of an injection reaches the blood.

Investigational

Still being studied and not approved by a regulator, such as the FDA, to treat any condition.

Lean mass

Everything in the body that is not fat, including muscle, organs, bone and water. Body scans measure it separately from fat.

mcg and mg

Micrograms and milligrams. 1 mg equals 1,000 mcg, so 0.6 mg is 600 mcg. Petrelintide amounts are usually written in mg.

Peptide

A short chain of amino acids. Petrelintide is a chain of 35 with a fatty-acid tail attached.

Pharmacokinetics

How the body absorbs, moves, breaks down and removes a substance. Half-life and bioavailability are pharmacokinetic measures.

Trial phases

Stages of testing in people. Phase 1 checks safety and blood levels, phase 2 tests doses in patients, and phase 3 confirms benefits and harms in large groups before approval.

Placebo

A dummy treatment with no active ingredient, used as a comparison in studies.

Preclinical research

Studies done before research in people: cell studies and animal studies.

Reconstitution

Mixing a freeze-dried powder with sterile water to make an injectable solution. The amount of water sets how much drug each syringe unit holds.

Research use only

A label on products sold for laboratory research. It does not mean a product is approved, tested for human use or legal to sell as a medicine.

Subcutaneous (SC)

Injected into the fatty layer just under the skin. This is the route used in every petrelintide weight-loss trial.

Syringe units

Markings on an insulin syringe that measure volume. On a U-100 syringe, 100 units equal 1 mL. The amount of drug per unit depends on the vial's concentration.

Titration and target dose

Titration means raising a dose in steps, usually to reduce side effects. The target (or maintenance) dose is the amount kept once the steps are finished.

WADA

The World Anti-Doping Agency, which publishes the list of substances banned in sport. Its category S0 covers drugs not approved for human use anywhere.

Weekly total

All the amounts given in one week, added together. For a once-weekly injection it equals the amount each time.

Explore more of the research

Go deeper into the laboratory and animal work behind the claims. Petrelintide's preclinical record is small: one full research paper and a series of company conference posters and abstracts, all from its developers. None of it tests a dose for people.

How this guide was researched

This guide is built from a thorough review of the sources cited throughout it: published clinical trials, company trial reports and conference data, registered study plans, regulatory documents, laboratory and animal research, and published protocol descriptions. We also reviewed public online forums and community education groups where people discuss petrelintide.

The guide cites 89 sources, including 9 original scientific papers. Only two of those papers are about petrelintide itself; the rest of its evidence comes from trial registries and from company conference posters, abstracts and presentations, which are labeled as such. Each type of source answers a different question. Trials show what researchers measured. Protocol descriptions show how petrelintide is described outside trials. Personal accounts show what individual people experienced. Every numbered citation links to its entry below, labeled by source type.

How this guide was made

Research and drafting were AI-assisted. Every cited source was checked against the original, and the guide was reviewed and edited by Doserly before publication. It has not had an independent clinical review, and Doserly does not currently have medical reviewers. Doserly makes a medication and health-tracking app and runs Doserly Academy, both of which are promoted in this guide. Read our editorial policy for how guides are researched, updated and corrected.

This guide is for educational purposes. It summarizes what the reviewed sources report so the research is easier to understand; it is not medical advice. For a deeper dive, or to check any point for yourself, go straight to the cited sources.

Explore the sources