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Mazdutide

Also known as IBI362, LY3305677, OXM-3

Dual GLP-1 and glucagon receptor agonist, approved in China for weight management and diabetes.

clinically proven Metabolic & weight approved drug

At a glance

Category
Metabolic & weight
Status
approved drug
Route
subcutaneous, once weekly
Half-life
not published in a figure we can verify; the pharmacokinetics support once-weekly subcutaneous dosing
Onset
weight loss from the first weeks; in GLORY-1 weight was still falling at week 48
Molecular weight
approximately 4563 g/mol
Sequence
39-amino-acid analogue of oxyntomodulin with a fatty-acyl side chain for albumin binding; the standardised sequence is not published in a form we can verify. Molecular formula C210H322N46O67.

Approved by China's National Medical Products Administration in June 2025 for long-term weight management in adults with a BMI of at least 28 kg/m2, or at least 24 kg/m2 with weight-related comorbidities, and in September 2025 for glycaemic control in adults with type 2 diabetes — the first GLP-1/glucagon dual agonist approved anywhere 5. Not approved by the FDA or EMA; development outside China is at an earlier stage. Developed by Innovent Biologics under licence from Eli Lilly.

Doping status: Not listed by WADA; approved in China, so the S0 non-approved-substance category does not apply

Checked against the WADA 2026 Prohibited List. For a specific product and country, Global DRO is the lookup athletes are expected to use — the List names substances, not brand names.

Mechanism of action

Mazdutide is a synthetic analogue of oxyntomodulin, a naturally occurring gut peptide produced from the same proglucagon precursor as GLP-1. Oxyntomodulin is a weak agonist at both the GLP-1 receptor and the glucagon receptor, and mazdutide engineers that dual activity into a molecule with a fatty-acyl chain that binds albumin and extends the half-life enough for weekly injection.

The GLP-1 arm delivers the familiar effects: glucose-dependent insulin secretion, glucagon suppression at the level of the alpha cell, delayed gastric emptying and central appetite reduction acting on the hypothalamus, area postrema and nucleus tractus solitarii.

The glucagon arm works mainly on liver and adipose tissue and pushes in the opposite direction from the appetite pathway: it raises energy expenditure, stimulates lipolysis and hepatic fatty acid oxidation, and lowers intrahepatic triglyceride. This is why the dual agonists reduce liver fat disproportionately to the weight they remove. In GLORY-1 liver fat content fell by up to roughly 80% at the doses studied.

The obvious tension in this design is that glucagon raises blood glucose. Mazdutide is deliberately GLP-1-weighted so that the incretin effect dominates glycaemically while the glucagon component contributes to energy expenditure. Getting that ratio right is the central engineering problem for this whole drug class, and it explains why glucagon-containing agonists also tend to raise heart rate. Unlike retatrutide, mazdutide contains no GIP component.

What the research shows

Mazdutide has a genuinely completed phase 3 programme, with the obesity trial published in the New England Journal of Medicine, the higher-dose obesity trial in JAMA, and two diabetes trials in Nature. That is a stronger published evidence base than any other GLP-1/glucagon dual agonist. The important caveat is that essentially all of it was generated in Chinese participants, who have a lower average BMI than Western obesity trial populations, so the results do not transfer automatically. There is no published cardiovascular outcome trial.

Research in humans

GLORY-1 (New England Journal of Medicine, 2025; n=610 Chinese adults with overweight or obesity, 48 weeks) reported a mean body-weight change of -12.55% with 6 mg and -10.09% with 4 mg against a placebo group that gained 0.45% at week 32 (treatment-policy estimand), and by week 48 49.5% of the 6 mg group had lost at least 15% of body weight compared with 2.0% on placebo. Liver fat content fell substantially. Discontinuation for adverse events was low. GLORY-2 (JAMA, 2026) tested a higher 9 mg dose in Chinese adults with obesity and reported a mean weight change of -16.65% at week 60 versus -1.50% with placebo. In type 2 diabetes, DREAMS-1 (mazdutide monotherapy versus placebo) and DREAMS-2 (mazdutide versus dulaglutide) were published back to back in Nature in 2026 and demonstrated HbA1c reduction with concurrent weight loss 34.

Animal and lab research

Preclinical work supports the combined mechanism of reduced energy intake via GLP-1 and increased energy expenditure via glucagon, with marked reductions in hepatic steatosis. Rodent thyroid C-cell proliferation is a class-wide finding for GLP-1 receptor agonists and remains a point of attention for this molecule as for the others. A 2025 EBioMedicine paper reported effects on diabetes-associated cognitive dysfunction in a rodent model; this is exploratory and has no established clinical meaning.

Caveats. The trials were funded and conducted by Innovent Biologics. Nearly all participants were Chinese, and the mean baseline BMI in GLORY-1 was around 34 kg/m2, lower than in Western obesity programmes — direct comparison of percentage weight loss against semaglutide or tirzepatide trials is therefore misleading. There is no published cardiovascular outcome trial and no long-term safety data beyond the trial durations. Increases in heart rate and in blood pressure-independent cardiac parameters attributable to the glucagon component need longer follow-up. Head-to-head comparisons against tirzepatide have not been published.

What it is used for

  • Chronic weight management in adults with obesity or overweight with a weight-related comorbidity (approved indication in China, June 2025) 5
  • Glycaemic control in adults with type 2 diabetes (approved indication in China, September 2025) 5
  • Studied for metabolic dysfunction-associated fatty liver disease, obstructive sleep apnoea and alcohol use disorder, none of them approved indications 5
  • Sold through grey-market channels outside China as an unregulated 'research chemical'; such material is not the approved product and its identity, strength and sterility are not verified by anyone. The FDA has warned about unapproved GLP-1 products sold direct to consumers under 'for research purposes' labelling, and about compounded GLP-1 drugs arriving warm or with inadequate ice packs 8

Dosing

Dose
4 mg or 6 mg once weekly for weight management as studied in GLORY-1; 9 mg once weekly studied in GLORY-2; lower doses used for glycaemic control
Frequency
once weekly
Route
Subcutaneous
Duration
48 weeks in the pivotal trials; the approved use is chronic
  • GLORY-1 used stepwise titration over the first weeks, starting well below the maintenance dose and stepping up at intervals of several weeks, before reaching 4 mg or 6 mg weekly. Those trial schedules are set out in the Protocols section below; the week-by-week table in the Chinese product label is a separate document and is not reproduced here.
  • Titration exists for tolerability: as with every agent in this class, gastrointestinal adverse events are dose-related and concentrated in the escalation phase.
  • The approved schedules are set out in the Chinese product information, which is the authoritative source. This entry is reference material, not treatment advice.
  • Doses circulating in online user protocols for grey-market mazdutide are not clinically validated and do not correspond to a verified product strength.
  • The schedules above describe the product licensed in China, which is a prefilled injection device. Outside China, mazdutide is also sold as lyophilised powder in vials with no approval anywhere, reconstituted and drawn up with an insulin syringe by the buyer. That removes the fixed-dose mechanism of the device, and the approved titration has not been validated for such material.
  • The milligram-versus-microgram trap is the single most likely way someone is harmed with this compound. Doses are expressed in milligrams; insulin syringes are marked in units, and one unit is a volume (0.01 ml), not a dose, so the same unit count means a different milligram amount at every concentration. The FDA's compounding risk alert of 26 July 2024, describing this exact vial-and-syringe failure mode for semaglutide, records patients self-administering five to twenty times the intended dose after confusing millilitres, milligrams and 'units', and reports that patients instructed to draw a 5-unit (0.05 ml) dose on a U-100 syringe administered 50 units instead 7.
  • Grey-market powder carries no guarantee of identity, purity, sterility or actual milligram content, so the number on the label may not be the number in the vial, and any calculation is only as good as that label. Mazdutide compounds the problem: the only licensed product is registered in China, is not distributed in the EU or US, and cannot serve as a practical reference against which a vial bought online might be checked.
  • The approved titration schedule exists because gastrointestinal effects are dose-limiting, and here the glucagon component adds a heart-rate effect that is also dose-related. GLORY-1 started well below the maintenance dose and stepped up over several weeks for that reason. Starting at 6 mg or 9 mg rather than titrating is how people end up vomiting for days and dehydrated, and with weekly-dosing pharmacokinetics an overdose does not resolve overnight.
  • The grey-market self-dosing pattern is set out as a circulating protocol below. The licensed product is a metered device registered only in China 5; what circulates elsewhere is reconstituted powder self-measured on an insulin syringe, with the milligram-to-unit conversion as the documented mechanism of harm 7. It is recorded because readers encounter it, not because it is validated.

These figures describe what the literature and published protocols report. They are not advice and not a dosing instruction.

Protocols

GLORY-1 phase 3, 4 mg arm (NCT05607680)

published trial

Source: ClinicalTrials.gov record NCT05607680 (GLORY-1, Innovent Biologics)

Weeks 1-42 mg subcutaneously once weekly
Weeks 5-484 mg subcutaneously once weekly

GLORY-1 is the phase 3 trial on which the Chinese approval for weight management rests. The registered Chinese product information may state a different schedule; it is not reproduced here because it could not be verified.

GLORY-1 phase 3, 6 mg arm (NCT05607680)

published trial

Source: ClinicalTrials.gov record NCT05607680 (GLORY-1, Innovent Biologics)

Weeks 1-42 mg subcutaneously once weekly
Weeks 5-84 mg subcutaneously once weekly
Weeks 9-486 mg subcutaneously once weekly

One extra four-week step compared with the 4 mg arm. The glucagon component makes heart rate dose-related as well as gastrointestinal tolerance, which is what the build-up is for.

Grey-market reconstituted powder (circulating)

user protocol — not validated

Source: GLP-1 forums and research-chemical vendor labelling; the licensed product is sold only in China

This is not a validated schedule. It is a pattern that circulates among users and sellers, reproduced because it is what people actually follow — not because it has been tested. No trial established these doses, this interval or this duration, and nobody is checking what is in the vial. Treat every number below as an assertion, not a finding.

Reported self-dosingroughly 2 mg weekly to start, stepping toward 4-6 mg (and 9 mg by some), copying the GLORY-1 arms — but drawn from reconstituted powder on an insulin syringe rather than from a metered device
How reports divergesome skip titration and start at the maintenance dose; vial strengths and reconstitution volumes are not standardised between sellers, so the same 'unit' count means a different milligram amount each time
Reported adverse patterndays of vomiting and dehydration after starting too high or mis-measuring, with the effects persisting because dosing is weekly

The trial arms above used a metered escalation of a validated formulation under supervision, and the only licensed mazdutide is a prefilled device registered in China 5. What circulates outside China is lyophilised powder of unverified identity, purity, sterility and milligram content, reconstituted and measured by the buyer — which removes the fixed-dose mechanism and reintroduces the milligram-to-unit trap. That trap is the single most likely way someone is harmed: doses are in milligrams, insulin syringes are marked in units of volume, and the FDA has recorded patients self-administering five to twenty times the intended dose of a compounded GLP-1 after confusing millilitres, milligrams and 'units' 7. Because there is no licensed mazdutide in the EU or US, there is no reference product against which a grey-market vial can be checked. The titration in the trials existed because gastrointestinal effects and the glucagon-driven heart-rate rise are dose-related 1; starting at the maintenance dose, as some reports describe, is how people end up vomiting and dehydrated for days, and weekly pharmacokinetics mean a tenfold error runs for days rather than hours 7. This is recorded because it circulates, not because it is safe.

Schedules are reproduced as their source states them. Units, IU and milligrams explains why the figures are not interchangeable between products.

Reconstitution

Vial sizes
10 mg
Solvent
bacteriostatic water (0.9% benzyl alcohol) — for grey-market powder only; the product licensed in China is a ready-made solution and is never reconstituted
Storage
Licensed presentation: refrigerated storage per the approved Chinese product information. Unregistered powder: no approved storage instruction exists, no stability data for such material have been published, and the FDA has received complaints that certain compounded GLP-1 drugs arrived warm or with inadequate ice packs to keep them at the recommended storage temperature.

Worked example

Two separate products, and the entry does not merge them. The product approved in China is supplied as a ready-to-use solution in a prefilled injection device at a validated concentration: nothing is dissolved, nothing is measured. Separately, mazdutide is sold outside China as lyophilised powder in vials with no approval anywhere, and that material is reconstituted and measured by the buyer. For such a vial: 10 mg vial + 2 ml bacteriostatic water = 5 mg/ml. A 4 mg dose is 0.8 ml, which is 80 units on a U100 insulin syringe; a 6 mg dose would be 1.2 ml, more than a full syringe — a sign that the concentration is wrong for the dose rather than a reason to inject twice. Reconstituting the same 10 mg vial with 1 ml instead gives 10 mg/ml, at which 4 mg is 40 units. The vial is unchanged; the meaning of a unit has doubled.

Vial strengths are not standardised between sellers. 10 mg is the size most commonly seen, but nothing obliges a seller to use it and other strengths appear, so concentration must be recalculated for every vial and a unit figure copied from another protocol is meaningless. The worked example is descriptive arithmetic, not a protocol. It changes nothing about the starting material: identity, purity, sterility and actual milligram content of grey-market mazdutide are unverified. The Chinese licensed device delivers a validated dose; the powder is a separate, unapproved supply route.

Work it out for Mazdutide

Safety

Side effects

  • Nausea, vomiting, diarrhoea and constipation — very common, dose-related and concentrated during titration
  • Decreased appetite, dyspepsia, abdominal distension
  • Increased heart rate, attributed largely to the glucagon receptor component
  • Injection-site reactions
  • Fatigue and headache
  • Transient increases in liver enzymes have been reported in glucagon-agonist programmes and warrant monitoring
  • Hypoglycaemia when combined with insulin or a sulfonylurea
  • Gallbladder disorders and pancreatitis are expected class effects; the trial populations were too small to quantify rare events reliably
  • Loss of fat-free mass alongside fat mass during rapid weight reduction
  • Delayed gastric emptying, with the associated risk of retained gastric contents and pulmonary aspiration under anaesthesia or deep sedation
  • Rare and long-latency adverse effects are unknown
  • Overdose from a dosing error with reconstituted powder: the adverse events the FDA recorded after such errors with compounded semaglutide were nausea, vomiting, abdominal pain, fainting, headache, migraine, dehydration, acute pancreatitis and gallstones 7, with the glucagon-driven heart-rate increase also dose-related. Weekly-dosing pharmacokinetics mean the effects of a tenfold error run for days rather than hours
  • Injection-site infection and abscess from non-sterile technique or non-sterile starting material — a vial-and-syringe risk that does not exist with the sealed licensed device

Do not use if

  • Personal or family history of medullary thyroid carcinoma (MTC) — class restriction for GLP-1 receptor agonists
  • Multiple endocrine neoplasia syndrome type 2 (MEN 2)
  • Known hypersensitivity to mazdutide or any excipient
  • History of pancreatitis
  • Type 1 diabetes and diabetic ketoacidosis
  • Severe gastrointestinal disease including gastroparesis
  • Pre-existing tachyarrhythmia or poorly controlled cardiac disease, given the heart-rate increase attributable to glucagon receptor activation
  • Pregnancy, breastfeeding and active plans to conceive
  • Use outside a regulated supply chain: material bought as a research chemical has no guarantee of identity, strength or sterility
  • Reconstituting and measuring unregulated powder without being able to do the milligram-to-unit conversion reliably. Errors at this step are the most frequently documented mechanism of harm with drugs in this class, and the FDA has recorded adverse events including hospitalisations from them 7
  • Any assumption that a grey-market vial contains what its label states. The only licensed mazdutide is registered in China and not distributed in the EU or US, so there is no practical reference product against which a vial could be checked

Interactions

Not comprehensively characterised outside the registration programme. The mechanistic expectations are those of the class: delayed gastric emptying can alter the absorption of oral medicines, and combination with insulin or sulfonylureas raises hypoglycaemia risk enough that those agents usually need dose reduction. The glucagon component can raise hepatic glucose output, which complicates titration of antidiabetic therapy. Mazdutide should not be combined with another GLP-1 receptor agonist or with a DPP-4 inhibitor. Because of delayed gastric emptying, anaesthesia guidance on modified preoperative fasting for GLP-1 receptor agonists applies.

Sources