Mazdutide (development codes IBI362 and LY3305677) is a once-weekly peptide that activates two receptors at once: the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR). The molecule originated at Eli Lilly and is developed in China by Innovent Biologics. This overview covers the receptor pharmacology, the scaffold it is built on, and the published clinical record, with citations listed at the end. Nothing here is a therapeutic claim, and all outcome statements from trials are reproduced as direct quotations with attribution.
The oxyntomodulin scaffold
Proglucagon is post-translationally processed into several peptides, among them glucagon, GLP-1 and oxyntomodulin. Oxyntomodulin is unusual in that a single naturally occurring sequence carries intrinsic activity at both the GLP-1 receptor and the glucagon receptor (Holst et al., 2018). That dual activity is the design starting point for mazdutide: rather than fusing two separate pharmacophores, the molecule is engineered from a template that is already dual by nature, with modifications intended to extend exposure to a weekly interval.
Receptor pharmacology
GLP-1R and GCGR are both class B (secretin family) G-protein-coupled receptors, and both couple predominantly to Gs and adenylate cyclase. They differ in tissue distribution and in the physiology they govern: GLP-1R is prominent in pancreatic islets and in central circuits, while GCGR is heavily expressed in hepatocytes. Research interest in dual GLP-1R/GCGR agonists therefore centres on how parallel activation of a central-and-islet receptor and a hepatic receptor behaves in the same system, in contrast to GLP-1R-only agonists or to the GLP-1R/GIPR pairing.
The published pharmacological description is direct. The phase 2 report opens:
"Mazdutide is a once-weekly glucagon-like peptide-1 (GLP-1) and glucagon receptor dual agonist."
Published clinical programme
The obesity programme was first reported in three peer-reviewed stages, all in Chinese adult populations with overweight or obesity. Further trials have since been published, including a US-based phase 2 trial (Hsia et al., 2026).
- Phase 1b (2021). "IBI362 (LY3305677), a weekly-dose GLP-1 and glucagon receptor dual agonist, in Chinese adults with overweight or obesity: A randomised, placebo-controlled, multiple ascending dose phase 1b study", Ji et al., EClinicalMedicine 2021;39:101088.
- Phase 2 (2023). A randomised, double-blind, placebo-controlled trial in Chinese adults with overweight or obesity; the published report is an interim analysis of the first 24 weeks (Ji et al., Nature Communications, 2023).
- Phase 3 GLORY-1 (2025). "Once-Weekly Mazdutide in Chinese Adults with Obesity or Overweight". The abstract background reads:
"Evidence suggests that incretin-based dual agonist pharmacotherapy is helpful in persons with obesity. Mazdutide, a glucagon-like peptide-1 and glucagon receptor dual agonist, may have efficacy in persons with overweight or obesity."
On the regulatory side, Innovent Biologics published a release on 27 June 2025 titled "Innovent Announces Mazdutide, First Dual GCG/GLP-1 Receptor Agonist, Received Approval from China's NMPA for Chronic Weight Management". Mazdutide is not approved in the United Kingdom, the European Union or the United States.
Where it sits among related compounds
Within the incretin-adjacent class, the distinguishing variable is which receptors a molecule recruits alongside GLP-1R:
- Mazdutide: GLP-1R + GCGR (oxyntomodulin-based dual agonist).
- Tirzepatide: GLP-1R + GIPR (dual agonist).
- Retatrutide: GLP-1R + GIPR + GCGR (described in the literature as a triple agonist).
For a receptor-level breakdown of the first two, see the mazdutide vs tirzepatide comparison. Because no head-to-head randomised trial has been published between mazdutide and either compound, no comparative outcome statement is made here.
Reference material and sourcing
Peptx stocks mazdutide as lyophilised reference material. The single vial listing is at /single-vials/mazdutide, which also shows current UK Express availability. As with any reference material, laboratories should confirm identity and purity for their own application: HPLC purity, mass spectrometry confirmation of molecular identity, and endotoxin testing where cell-based assays are involved. Independent verification routes are listed on the research labs directory, and published certificates are collected in the COA Library.
All material is supplied for laboratory, academic or institutional research only. It is not for human or animal consumption.
References
- Holst JJ, et al. (2018). Oxyntomodulin: Actions and role in diabetes. Peptides. PubMed 29412831
- Hsia SH, et al. (2026). Efficacy and safety of mazdutide in adults with obesity or overweight: a US-based, multicentre, phase 2, randomised, placebo-controlled clinical trial. The Lancet Diabetes & Endocrinology. PubMed 42628555
- Ji L, et al. (2021). IBI362 (LY3305677), a weekly-dose GLP-1 and glucagon receptor dual agonist, in Chinese adults with overweight or obesity: A randomised, placebo-controlled, multiple ascending dose phase 1b study. EClinicalMedicine. PubMed 34430840
- Ji L, et al. (2023). A phase 2 randomised controlled trial of mazdutide in Chinese overweight adults or adults with obesity. Nature Communications. PubMed 38092790
- Ji L, et al. (2025). Once-Weekly Mazdutide in Chinese Adults with Obesity or Overweight. New England Journal of Medicine. PubMed 40421736