Pinc PeptideThe girly peptide research blog

Weight loss · Evidence tier A

Mazdutide

LY3305677 (Eli Lilly development code) · IBI362 (Innovent development code) · Xinermei (brand name in China)

Mazdutide is a weekly weight-loss and diabetes injection, approved in China in 2025, not in the US123. In a 48-week trial, Chinese adults with excess weight lost 11.0% to 14.0% of body weight, versus a 0.3% gain on placebo4.

Illustration: a glass vial with a pink label reading Mazdutide
Illustration, not a real product: an empty glass vial (photo: Missouri Historical Society, public domain) with our label. See every vial.

Quick answers

What is it?
A weekly injection from Eli Lilly that Innovent Biologics develops in China under a 2019 license56. This lab-made peptide acts like two hormones at once, GLP-1 and glucagon6. China approved it in 2025 as Xinermei, for weight management and type 2 diabetes6.
Does it work?
Yes, in large trials, mostly in China. Over 48 weeks, adults with obesity or overweight lost 11.0% to 14.0% of their weight, versus a 0.3% gain on placebo4. At a higher dose over 60 weeks, adults with obesity lost 16.65% versus 1.50% on placebo7.
Is it safe?
Not fully known. Gut side effects are common: in a 60-week trial, 53.1% vomited and 46.9% had nausea, versus 1.3% and 3.2% on placebo7. In a US trial, 20% stopped the highest dose tested (16 mg) because of side effects8.
Is it legal?
It is approved in China and Macau, but not in the US35. By our reading, US pharmacies may not make it910. FDA has warned companies that sold it falsely labeled “for research purposes”11. In sport, it is likely allowed, by our reading1213.
What is in the vials?
More than a third of tested samples failed. Of 29 tests that Finnrick, an independent testing service, listed from April to November 2025, 11 failed14. A pass needs at least 99.5% purity and a dose within 35% of the label14.

What it is

Mazdutide (development codes LY3305677 and IBI362) is a lab-made peptide of 34 amino acids that activates two hormone receptors: the receptor for GLP-1 (glucagon-like peptide-1) and the glucagon receptor615. It is a long-acting synthetic version of oxyntomodulin, a natural gut hormone whose appetite-reducing effect comes through the GLP-1 receptor and whose rise in energy expenditure comes through the glucagon receptor16. Innovent says the glucagon receptor activity may also raise energy expenditure and improve how the liver handles fat1. A fatty-acid chain extends its half-life, so it is injected under the skin once a week16.

Mazdutide is an Eli Lilly molecule (LY3305677). In 2019 Innovent Biologics took an exclusive license from Lilly to develop and sell it in China, and Innovent lists its rights as covering mainland China, Hong Kong, Macau and Taiwan5. China’s National Medical Products Administration (NMPA) approved it in June 2025 for chronic weight management and in September 2025 for blood sugar control in type 2 diabetes126. Macau followed in October 2025 and January 20265. Lilly has run its own Phase 1 and 2 trials in the US, the UK, Germany and Argentina817.

Benefits: what the research shows

Mazdutide has been tested in large controlled trials, nearly all in China. In GLORY-1, 610 Chinese adults with obesity or overweight (BMI 28 or more, or 24 to under 28 with a weight-related condition) received 4 mg or 6 mg weekly or placebo for 48 weeks; weight changed by -11.0% and -14.0% versus +0.3% on placebo, counting people who stopped treatment or started other weight-loss therapy4. By the efficacy estimand, which assumes everyone stayed on treatment, Innovent reported weight changes at week 48 of -12.0%, -14.8% and -0.5%; in people whose liver fat was at least 10% at the start, liver fat fell by 65.9% and 80.2% versus 5.3%1. GLORY-2 tested 9 mg against placebo in 461 Chinese adults with obesity for 60 weeks: weight fell 16.65% versus 1.50%, and 84.3% versus 33.1% lost at least 5%7. In type 2 diabetes, DREAMS-1 (320 adults) lowered HbA1c (average blood sugar) by 1.57 and 2.15 points on 4 and 6 mg versus 0.14 on placebo at 24 weeks19, and DREAMS-2 (731 adults) lowered HbA1c by 0.24 and 0.30 points more than dulaglutide 1.5 mg, and weight by 3.78 and 5.76 percentage points more, at 28 weeks20. Innovent reported that in DREAMS-3, an open-label trial in 349 adults with type 2 diabetes and obesity, 6 mg lowered weight by 10.29% versus 6.00% on semaglutide 1 mg over 32 weeks21. There are important limits. All 11 Phase 3 trials that list mazdutide on ClinicalTrials.gov are in China, and 9 are sponsored by Innovent17; Innovent funded GLORY-14. Outside China the evidence is smaller. In a Lilly-funded US Phase 2 trial of 179 adults, weight fell 7.3% (3 mg, later 6 mg), 15.6% (10 mg) and 18.1% (16 mg) versus 0.9% on placebo at 32 weeks by the efficacy estimand, with further losses by 48 weeks8. In a Lilly-funded US Phase 1 trial of 32 adults, weight fell 20.0% and 21.0% over 20 weeks at a 16 mg target dose, versus 0.1% on placebo22. DREAMS-3 has been reported only in a company press release21. The longest published trial ran 60 weeks7, so long-term effects and effects on heart attacks and strokes are unknown. Lilly’s public pipeline (data as of 5 August 2026) does not list mazdutide, though Lilly says some molecules are not identified for competitive reasons23.

Key human studies

StudyDesignPeopleDose and routeResult
Ji et al., N Engl J Med 2025 (GLORY-1)4PubMed · DOI · NCT05607680 Phase 3 randomized, double-blind, placebo-controlled trial in China (1:1:1), 48 weeks; adults with BMI 28 or more, or 24 to under 28 with a weight-related condition 610 4 mg or 6 mg subcutaneous once weekly, or placebo Body weight -11.00% (4 mg) and -14.01% (6 mg) vs +0.30% with placebo at week 48 (treatment-policy estimand). Adverse events led 1.5%, 0.5% and 1.0% to stop; gastrointestinal events were the most common, mostly mild to moderate4.
Gao et al., JAMA 2026 (GLORY-2)7PubMed · DOI · NCT06164873 Phase 3 randomized, double-blind, placebo-controlled trial (2:1), 60 weeks, at 27 hospitals in China; adults with BMI 30 or more, 16.1% with type 2 diabetes 461 9 mg subcutaneous once weekly, or placebo, with diet and activity advice Body weight -16.65% vs -1.50% with placebo; 84.3% vs 33.1% lost 5% or more. Vomiting 53.1% vs 1.3%, nausea 46.9% vs 3.2%, diarrhea 39.4% vs 6.5%; adverse events led 2.9% vs 0% to stop7.
Guo et al., Nature 2026 (DREAMS-2)20PubMed · DOI · NCT05606913 Phase 3 randomized trial against an active comparator (1:1:1), 28 weeks; Chinese adults with type 2 diabetes on oral diabetes drugs 731 4 mg or 6 mg subcutaneous once weekly, or dulaglutide 1.5 mg once weekly HbA1c down 0.24 and 0.30 points more than with dulaglutide; body weight down 3.78 and 5.76 percentage points more. Gastrointestinal adverse events were more common than with dulaglutide20.
Zhu et al., Nature 2026 (DREAMS-1)19PubMed · DOI · NCT05628311 Phase 3 randomized, placebo-controlled trial (1:1:1), 24 weeks, then 24 weeks of extended mazdutide treatment; Chinese adults with type 2 diabetes not controlled by diet and exercise (mean HbA1c 8.24%) 320 4 mg or 6 mg subcutaneous once weekly, or placebo HbA1c -1.57 and -2.15 points vs -0.14 with placebo at week 24; body weight -5.61% and -7.81% vs -1.26%19.
Hsia et al., Lancet Diabetes Endocrinol 20268PubMed · DOI · NCT06124807 Phase 2 randomized, double-blind, placebo-controlled trial, 48 weeks, at 24 US centers; adults with obesity or overweight, without type 2 diabetes 179 3 mg then 6 mg (from week 32), 10 mg or 16 mg subcutaneous once weekly, or placebo Body weight -7.3%, -15.6% and -18.1% vs -0.9% with placebo at 32 weeks (efficacy estimand), with further losses by 48 weeks. Adverse events led 20% on 16 mg to stop, mainly gastrointestinal8.
Bhattachar et al., Diabetes Obes Metab 202522PubMed · DOI · NCT05623839 Phase 1 randomized, double-blind, placebo-controlled trial, 20 weeks, in the US; adults with overweight or obesity, without diabetes 32 Two dose-escalation schemes to a 16 mg target dose, subcutaneous once weekly, or placebo Body weight -20.0% and -21.0% in the two mazdutide groups vs -0.1% with placebo; no serious adverse events. Pulse rose by 10 beats per minute or more at two consecutive visits in 91.7% vs 37.5% on placebo22.

Doses studied

Doses below are what studies used or what a label says. They are not advice, and gray-market products may not contain what their label says.

In human studies

No dose is approved in the US. In China, the approved doses are 4 mg and 6 mg once weekly5, and a 9 mg dose was under review as of 25 August 202632. Trials used 4 mg or 6 mg weekly for 48 weeks in obesity4 and for 24 or 28 weeks in type 2 diabetes1920, and 9 mg weekly for 60 weeks in obesity7, all injected under the skin. Lilly’s US trials tested weekly doses of up to 16 mg822.

In animal studies

Not summarized. Mazdutide has been tested directly in large human trials, so this entry does not rely on animal doses.

What users report

No community dosing page was cited for this compound.

Half-life
About 6 to 17 days16Range in a 12-week study in 36 Chinese adults with overweight or obesity, at doses up to 6 mg weekly (150.9 to 403.5 hours). A 12-week study in type 2 diabetes reported 6.1 to 28.1 days38.
Routes
  • Subcutaneous injection once weekly (approved in China; the only route in the human studies we found)
  • No human data found for any other route

Every dose studied for Mazdutide, with sources →

Quality and the gray market

What testing finds

Finnrick, an independent testing service, listed 29 mazdutide tests dated 25 April 2025 to 25 November 2025: 18 passed and 11 failed (as displayed on 7 October 2026)14. Its default “Purity focus” standard requires purity of at least 99.5% and a measured dose within 35% of the label14. A Finnrick correction dated 1 August 2025 says one vendor’s mazdutide results were under review14. Finnrick also offers free mail-in testing to US users, so by our reading its results may not represent the whole market14.

How it is sold

Outside China, mazdutide is sold online as vials labeled for research use. FDA says companies have illegally sold unapproved drugs containing mazdutide and other GLP-1 drugs, falsely labeled “for research purposes” or “not for human consumption”, directly to consumers for human use with dosing instructions (page current 1 October 2026)11. As of 7 October 2026, FDA’s warning-letter database listed four letters naming mazdutide26. On 10 December 2024 FDA wrote to Summit Research Peptides, whose website, reviewed in October 2024, offered “Mazdutide” alongside semaglutide, tirzepatide, retatrutide and cagrilintide under “RESEARCH USE ONLY” labels27, and to Xcel Research LLC, which offered “MAZDUTIDE” and “SURVODUTIDE”28. In a letter of 31 March 2026, FDA quoted a Prime Sciences product page: “In a phase 3 trial (GLORY-1), once-weekly mazdutide led to an average body weight reduction of up to 14.8%”, on products labeled for “laboratory research purposes only”29. That figure matches Innovent’s 48-week efficacy-estimand result for 6 mg1. On 24 August 2026 FDA told NuScience Peptides LLC that its “Mazdutide” product was an unapproved new drug30. We found no verified price or demand data.

Side effects and risks

  • Gut side effects are very common: in GLORY-2, 53.1% vomited, 46.9% had nausea and 39.4% had diarrhea on 9 mg, versus 1.3%, 3.2% and 6.5% on placebo7. In a US trial, 20% stopped the 16 mg dose because of adverse events, mainly gastrointestinal8.
  • Pulse rises: in a small US trial, pulse rose by 10 beats per minute or more at two consecutive visits in 91.7% of people on mazdutide versus 37.5% on placebo22. An early study found mild, symptomless heart findings on ECG in three people on mazdutide16.
  • Some people make antibodies against the drug: 2 of 24 on mazdutide in one early study16, and 4 of 24 versus 1 of 12 on placebo in another, none of them neutralizing38.
  • Long-term effects, and effects on heart attacks, strokes and deaths, are unknown; the longest published trial ran 60 weeks7.
  • Gray-market products are of unknown quality: 11 of 29 Finnrick tests of mazdutide failed14.
  • Legal risk: in the US, mazdutide sold for human use is an unapproved new drug, and FDA has warned sellers1130.

Questions people ask

Is mazdutide FDA approved?

No. Drugs@FDA lists no product containing it (data updated 6 October 2026)3. It is approved in China, as Xinermei, and in Macau56.

What is Xinermei?

Xinermei is the brand name of mazdutide in China, where Innovent Biologics holds the rights to sell it56. China approved it in June 2025 for long-term weight management in adults with a BMI of 28 or more, or 24 or more with a weight-related condition, and in September 2025 for type 2 diabetes6.

How much weight do people lose on mazdutide?

In GLORY-1, Chinese adults with obesity or overweight lost 11.0% (4 mg) and 14.0% (6 mg) of their weight over 48 weeks, versus a 0.3% gain on placebo4. In GLORY-2, adults with obesity on 9 mg lost 16.65% over 60 weeks, versus 1.50% on placebo7. A US trial found 18.1% loss at 32 weeks on 16 mg, versus 0.9% on placebo, by the efficacy estimand8.

Mazdutide vs semaglutide: which works better?

In DREAMS-3, an open-label trial in 349 Chinese adults with type 2 diabetes and obesity, Innovent reported that 6 mg mazdutide lowered weight by 10.29% versus 6.00% on semaglutide 1 mg over 32 weeks, and HbA1c by 2.03 versus 1.84 points21. These results come from a company press release. A second head-to-head trial, in fatty liver disease, was still running when we checked517.

Is Lilly developing mazdutide in the US?

Lilly has tested it in US trials, including a Phase 2 obesity trial in 179 adults and a Phase 2 trial in alcohol use disorder that finished in May 2026824. We found no Lilly announcement of plans to seek FDA approval, and its public pipeline (data as of 5 August 2026) does not list mazdutide23.

What are the side effects of mazdutide?

Mostly gut effects: in GLORY-2, 53.1% vomited, 46.9% had nausea and 39.4% had diarrhea on 9 mg, versus 1.3%, 3.2% and 6.5% on placebo, and most cases were mild to moderate7. Pulse also rose in most people in a small US trial22.

Is mazdutide banned in sport?

It is not named on WADA’s 2026 or 2027 Prohibited List1213. Because it is approved in China, by our reading it falls outside S0, WADA’s ban on non-approved substances, so it is likely allowed112. This is not a WADA ruling.

What is still unknown

  • Whether and when Lilly will seek approval in the US or Europe.
  • Peer-reviewed results of DREAMS-3 (company press release only, as of 7 October 2026).
  • Why Innovent’s GLORY-2 press release of 19 November 2025 gave larger weight losses than the JAMA paper; the release did not name its estimand. This entry uses the paper.
  • Effects beyond 60 weeks, and on heart attacks, strokes and deaths.
  • Results of Lilly’s alcohol use disorder trial (completed 19 May 2026; no results posted as of 7 October 2026).
  • China’s decision on the 9 mg dose (under review as of 25 August 2026).
  • The Chinese characters of the brand name Xinermei (not verified).
  • Whether mazdutide has a USP or NF monograph (not checked).
  • UK, EU, Canadian and wider Australian rules (not verified).
  • WADA has not ruled on mazdutide by name; the likely-allowed status is our reading of the List.

Sources

  1. 1Voluntary Announcement: First Dual GCG/GLP-1 Receptor Agonist Mazdutide Received Approval by the National Medical Products Administration for Chronic Weight Management Innovent Biologics, Inc. (HKEXnews), 27 Jun 2025. www1.hkexnews.hk
  2. 2Voluntary Announcement: Mazdutide Received Approval from China’s National Medical Products Administration for Glycemic Control in Adults with Type 2 Diabetes Innovent Biologics, Inc. (HKEXnews), 19 Sep 2025. www1.hkexnews.hk
  3. 3Drugs@FDA via openFDA: search for active ingredient mazdutide (no matches) U.S. Food and Drug Administration (openFDA), 6 Oct 2026. api.fda.gov · data query
  4. 4Once-Weekly Mazdutide in Chinese Adults with Obesity or Overweight New England Journal of Medicine, 12 Jun 2025. pubmed.ncbi.nlm.nih.gov
  5. 5Annual Report 2025 Innovent Biologics, Inc. (HKEXnews), 28 Apr 2026. www1.hkexnews.hk
  6. 6Mazdutide: First Approval Drugs, Dec 2025. pubmed.ncbi.nlm.nih.gov
  7. 7Treatment With 9-mg Mazdutide for Weight Reduction in Chinese Adults With Obesity: The GLORY-2 Randomized Clinical Trial JAMA, 4 Aug 2026. pubmed.ncbi.nlm.nih.gov
  8. 8Efficacy 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, 21 Aug 2026. pubmed.ncbi.nlm.nih.gov
  9. 9Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act U.S. Food and Drug Administration, 14 May 2026. fda.gov
  10. 10Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 14 May 2026. fda.gov
  11. 11FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss U.S. Food and Drug Administration, 1 Oct 2026. fda.gov
  12. 12World Anti-Doping Code International Standard: Prohibited List 2026 World Anti-Doping Agency, 24 Sep 2025. wada-ama.org
  13. 13World Anti-Doping Code International Standard: Prohibited List 2027 World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  14. 14Mazdutide Safety Testing Results & Vendor Ratings Finnrick, accessed 7 Oct 2026. finnrick.com
  15. 15KEGG DRUG: Mazdutide (D12225) KEGG, Kanehisa Laboratories, accessed 7 Oct 2026. kegg.jp
  16. 16IBI362 (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, Sep 2021. pubmed.ncbi.nlm.nih.gov
  17. 17ClinicalTrials.gov search: studies with the intervention mazdutide, LY3305677 or IBI362 (45 records) ClinicalTrials.gov, accessed 7 Oct 2026. clinicaltrials.gov
  18. 18Proposed International Nonproprietary Names: List 126 (WHO Drug Information, Vol. 35, No. 4) World Health Organization, 2021. cdn.who.int
  19. 19Mazdutide versus placebo in Chinese adults with type 2 diabetes Nature, Apr 2026. pubmed.ncbi.nlm.nih.gov
  20. 20Mazdutide versus dulaglutide in Chinese adults with type 2 diabetes Nature, Apr 2026. pubmed.ncbi.nlm.nih.gov
  21. 21Innovent’s Mazdutide Shows Superiority in Glycemic Control with Weight Loss over Semaglutide in a Head-to-head Phase 3 Clinical Trial DREAMS-3 Innovent Biologics (PR Newswire), 26 Oct 2025. prnewswire.com
  22. 22Mazdutide reduces body weight in adults with overweight or obesity: A high-dose Phase 1 trial Diabetes, Obesity and Metabolism, Nov 2025. pubmed.ncbi.nlm.nih.gov
  23. 23Clinical Development Pipeline Eli Lilly and Company, 5 Aug 2026. lilly.com
  24. 24A Study to Evaluate Mazdutide Compared With Placebo in Participants With Alcohol Use Disorder (NCT06817356) ClinicalTrials.gov, 16 Jul 2026. clinicaltrials.gov
  25. 25A Master Protocol Study (LY900038) of Multiple Intervention-Specific-Appendices (ISAs) in Adult Participants With Obesity or Overweight (NCT06143956) ClinicalTrials.gov, 8 Sep 2026. clinicaltrials.gov
  26. 26Warning Letters (database search for mazdutide) U.S. Food and Drug Administration, accessed 7 Oct 2026. fda.gov
  27. 27Warning letter to Summit Research Peptides (MARCS-CMS 695607) U.S. Food and Drug Administration, 10 Dec 2024. fda.gov
  28. 28Warning letter to Xcel Research LLC (MARCS-CMS 694608) U.S. Food and Drug Administration, 10 Dec 2024. fda.gov
  29. 29Warning letter to Prime Sciences (MARCS-CMS 721805) U.S. Food and Drug Administration, 31 Mar 2026. fda.gov
  30. 30Warning letter to NuScience Peptides LLC (MARCS-CMS 733652) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  31. 3121 CFR 216.23, Bulk drug substances that can be used to compound drug products in accordance with section 503A (eCFR, as of 25 September 2026) Electronic Code of Federal Regulations (eCFR), 25 Sep 2026. ecfr.gov
  32. 32Interim Results Announcement for the Six Months Ended 30 June 2026 Innovent Biologics, Inc. (HKEXnews), 25 Aug 2026. www1.hkexnews.hk
  33. 33Mazdutide 9mg Supplementary Application Accepted for Review by China’s NMPA, Potentially Offering a Novel Drug Option for Moderate-to-Severe Obese Population Innovent Biologics (PR Newswire), 25 Nov 2025. prnewswire.com
  34. 34Therapeutic Goods (Poisons Standard—October 2026) Instrument 2026 (F2026L01327) Federal Register of Legislation, Australian Government, 28 Sep 2026. legislation.gov.au
  35. 35WADA publishes 2027 Prohibited List World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  36. 36The 2027 Monitoring Program World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  37. 37Summary of Major Modifications and Explanatory Notes: 2027 Prohibited List World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  38. 38A phase 1b randomised controlled trial of a glucagon-like peptide-1 and glucagon receptor dual agonist IBI362 (LY3305677) in Chinese patients with type 2 diabetes Nature Communications, 24 Jun 2022. pubmed.ncbi.nlm.nih.gov

Not medical advice. This page reports what studies and regulators say; it does not recommend using any product. How we grade evidence · Report an error.