What mazdutide is
Mazdutide is a synthetic, single-chain lipidated peptide that acts as an agonist at the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR). It was discovered at Eli Lilly under the code LY3305677 and licensed to Innovent Biologics for development in China, where it is known as IBI362. Unlike the glucagon-based survodutide or the GIP-based tirzepatide, mazdutide is an analogue of oxyntomodulin, the 37-residue proglucagon product that is the body's own dual agonist at these two receptors [1].
Native oxyntomodulin is a weak agonist at both receptors and is cleared within minutes. Mazdutide keeps the oxyntomodulin framework and adds the modifications that have become standard for long-acting proglucagon-family peptides: substitutions that resist dipeptidyl peptidase-4 and raise potency, and a fatty-acid side chain that binds albumin and extends the half-life to the range that supports once-weekly dosing. The potency balance between the two receptors is tuned so that the glucagon component contributes to energy expenditure and hepatic fat handling without raising blood glucose.
The research material is a white to off-white lyophilised powder. As with other development-stage peptides, the identifiers that appear routinely on the certificates of licensed compounds are not standardised in public databases for mazdutide, and a certificate should state the sequence and expected mass against which the batch was tested.
| Identifier | Value |
|---|---|
| Development codes | IBI362 (Innovent), LY3305677 (Lilly) |
| Class | GLP-1/glucagon receptor dual agonist |
| Backbone | Oxyntomodulin analogue |
| Lipidation | Fatty-acid side chain (albumin binding) |
| Half-life in humans | Supports once-weekly dosing |
| Appearance | White lyophilised powder |
| Catalogue sizes | 10 mg |
How the literature describes its mechanism
Oxyntomodulin is secreted from intestinal L-cells alongside GLP-1 and activates both the GLP-1 and glucagon receptors. In the 2000s, infusion studies in humans showed that it reduced food intake and modestly raised energy expenditure, which made it the prototype for the dual-agonist concept. The problem was its short half-life and low potency; mazdutide is one of several synthetic attempts to keep the receptor profile while fixing the pharmacokinetics.
The pharmacological rationale is the same as for the other glucagon-containing agonists. The GLP-1 component reduces food intake, slows gastric emptying and potentiates glucose-dependent insulin secretion; the glucagon component increases energy expenditure and promotes hepatic lipid oxidation in the models used, and in a balanced dual agonist its glucose-raising effect is offset by the incretin activity. In the phase 2 trial report, Ji and colleagues note that the clinical programme was designed to test whether this balance produces greater weight reduction and liver-fat reduction than GLP-1 receptor agonism alone [1].
For an in-vitro programme the relevant readouts are cAMP accumulation in cells expressing human GLP-1R or GCGR, selectivity against the GIP receptor, and hepatocyte lipid-metabolism assays. As for all lipidated peptides, measured potency depends on the albumin content of the assay medium, because albumin-bound peptide is not free to engage the receptor.
The clinical research record
Mazdutide has been developed primarily in China, and its trial record reflects that.
Ji and colleagues reported a 24-week phase 2 trial in 248 Chinese adults with overweight or obesity. The highest dose produced a mean weight reduction of about 11 per cent against about 1 per cent on placebo, with reductions in waist circumference, blood pressure, liver fat and lipids, and the gastrointestinal adverse-event profile typical of the class [1].
GLORY-1, the phase 3 trial, randomised 610 Chinese adults with overweight or obesity to mazdutide 4 mg, 6 mg or placebo for 48 weeks. Mean weight reduction was about 11 per cent at 4 mg and 14 per cent at 6 mg, against about 0.5 per cent on placebo, with improvements across cardiometabolic markers [2]. A separate phase 3 programme in type 2 diabetes (DREAMS) has reported, and higher-dose studies in obesity are in progress. On the strength of GLORY-1, mazdutide received marketing approval from China's National Medical Products Administration in 2025 for long-term weight management, which makes it the first glucagon/GLP-1 dual agonist to be licensed anywhere.
Regulatory status in the United Kingdom
Mazdutide has no marketing authorisation in the UK, the EU or the United States. Its Chinese approval has no legal effect in this country. It is not a medicine here, is not controlled under the Misuse of Drugs Act, and is supplied as a chemical for in-vitro laboratory use under the Terms of Sale. It is not for human or veterinary administration. Purchasers must be 18 or over and are responsible for ensuring their use of the material complies with the laws and institutional rules that apply to them. Our guide to the UK rules on research compounds sets this out in more detail.
In sport, GLP-1 receptor agonists are listed on the WADA Prohibited List under S4.5, and a dual agonist with GLP-1 receptor activity falls within that class.
Handling, storage and stability
Mazdutide is supplied lyophilised, sealed under nitrogen in a glass vial with a rubber stopper and an aluminium flip-off crimp.
Sealed vial. Store at 2–8 °C for routine use and at −20 °C or below for storage beyond a few months. Protect from light. Allow a refrigerated vial to reach room temperature before opening.
Reconstitution. Reconstitute in sterile bacteriostatic water, sterile water, or an assay-appropriate buffer, adding the solvent down the side of the vial and swirling gently. Oxyntomodulin-family peptides share glucagon's tendency to aggregate at neutral pH and high concentration; the lipidated analogue is better behaved than the native hormone but should still not be shaken. The reconstitution calculator gives the volume for a target concentration.
Reconstituted solution. Keep at 2–8 °C, protected from light, and use within 28 days as a conservative practice. Discard any solution that becomes cloudy. Do not freeze after reconstitution unless the buffer has been validated for it.
Solubility and surfaces. The lipid side chain makes the molecule amphipathic; use low-binding tubes and PES or PVDF membranes, since the compound adsorbs to nylon and ordinary polypropylene at low concentration. The storage and stability guide covers lipidated peptides in general.
What a sound certificate for mazdutide looks like
Every batch we release carries an independent certificate of analysis, transcribed on the product page and in the certificate register.
Purity by RP-HPLC. Reversed-phase HPLC on a C18 column with UV detection at 214 or 220 nm, reporting the main peak as a percentage of all integrated peaks. A good batch shows a single dominant peak at 98% or above.
Identity by LC-MS. The certificate must state the sequence and expected mass it tested against, and the deconvoluted observed mass should agree to within a few tenths of a dalton. A certificate that reports identity as "conforms" without a mass figure is not adequate for a development compound with no public reference standard.
Net peptide content. Reported where available, since the lyophilised powder carries bound water and trifluoroacetate.
Endotoxin. Where tested, a LAL result in endotoxin units per milligram.
Our guide to reading a certificate of analysis goes through a complete report line by line.
Related compounds
Survodutide is the other glucagon/GLP-1 dual agonist in the catalogue, built on the glucagon sequence rather than oxyntomodulin. GLP-3 (retatrutide) adds GIP receptor activity to make a triple agonist. Tirzepatide activates GIP and GLP-1 but not glucagon, and semaglutide is the selective GLP-1 comparator. The family is compared in our GLP-1 family comparison.
Frequently asked questions
Is mazdutide a licensed medicine? In China, yes, since 2025. In the UK, no, and the research material supplied here is not a medicine.
What is the difference between IBI362 and LY3305677? They are the same molecule. LY3305677 is Lilly's discovery code and IBI362 is Innovent's development code in China.
How does mazdutide differ from survodutide? Both activate GLP-1 and glucagon receptors, but they are built on different parent sequences (oxyntomodulin and glucagon respectively), with different lipidation chemistry and different receptor potency ratios.
Why is there no CAS number on the certificate? Development compounds do not always have a CAS registration in general use. The sequence and mass stated on the certificate are the reliable identifiers.
References
- Ji L, Jiang H, Cheng Z, et al. A phase 2 randomised controlled trial of mazdutide in Chinese overweight adults or adults with obesity. Nature Communications. 2023;14:8289. doi:10.1038/s41467-023-44067-4.
- Ji L, Jiang H, Bi Y, et al. Once-weekly mazdutide in Chinese adults with obesity or overweight (GLORY-1). New England Journal of Medicine. 2025;392(22):2215–2225. doi:10.1056/NEJMoa2411528.
This monograph summarises the published literature for laboratory researchers. It is not medical advice, and nothing on this site is for human or veterinary use.