Mazdutide (Maiyoute): The Complete Guide

Overview

Mazdutide (also known by its development codes IBI362 and LY3305677) is a synthetic analog of oxyntomodulin, a naturally occurring gut hormone that activates both the GLP-1 receptor and the glucagon receptor. The molecule was originally developed by Eli Lilly and subsequently licensed to Innovent Biologics for development and commercialization in China. Innovent has driven the clinical development program, including the pivotal Phase 3 GLORY trial series that led to the world's first regulatory approval of a dual GLP-1/glucagon agonist (Ji et al., 2023).

The rationale for dual GLP-1/glucagon agonism stems from the complementary metabolic actions of these two receptor systems. GLP-1 receptor activation suppresses appetite, enhances glucose-dependent insulin secretion, and slows gastric emptying — the mechanisms responsible for the weight loss and glycemic benefits of drugs like semaglutide and liraglutide. Glucagon receptor activation adds distinct metabolic effects: it increases hepatic lipid oxidation, promotes thermogenesis (energy expenditure), reduces liver fat, and enhances amino acid metabolism. The hypothesis driving dual agonist development is that combining both activities in a single molecule produces greater and more metabolically comprehensive weight loss than GLP-1 agonism alone (Ambery et al., 2018).

Mazdutide joins a growing class of dual and multi-receptor agonists that also includes survodutide (Boehringer Ingelheim's dual GLP-1/glucagon agonist), pemvidutide (Altimmune), and the triple agonist retatrutide (Eli Lilly; GLP-1/GIP/glucagon). However, mazdutide distinguished itself by being the first to reach regulatory approval, achieving this milestone in China before any competitor reached approval in any market (Nahra et al., 2024).

The clinical development program has focused primarily on obesity and type 2 diabetes, with emerging data in metabolic dysfunction-associated steatohepatitis (MASH, formerly NASH) and non-alcoholic fatty liver disease (NAFLD). Mazdutide's glucagon receptor activity gives it a theoretical and early clinical advantage in liver-related endpoints, since glucagon signaling directly promotes hepatic fat oxidation — a mechanism absent from pure GLP-1 agonists (Romero-Gomez et al., 2023).

Quick Facts

Mazdutide in the GLP-1 Drug Landscape

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How It Works

Mazdutide's pharmacology is built on the biology of oxyntomodulin (OXM), a 37-amino-acid peptide secreted by intestinal L-cells after meals. Native OXM is a weak agonist at both the GLP-1 receptor and the glucagon receptor, but its short plasma half-life (approximately 12 minutes) limits its therapeutic utility. Mazdutide addresses this limitation through structural modifications — including fatty acid acylation that promotes albumin binding — which extend its half-life to support once-weekly dosing while enhancing potency at both receptor targets (Ji et al., 2023).

GLP-1 Receptor Agonism

The GLP-1 receptor component of mazdutide's action is responsible for the majority of its appetite-suppressing and glycemic effects. When mazdutide binds to GLP-1 receptors in the brain and periphery, it triggers several physiological responses:

• Appetite suppression: GLP-1 receptor activation in the hypothalamic arcuate nucleus and brainstem nucleus tractus solitarius reduces hunger signaling and promotes satiety. This is the primary driver of caloric reduction and, consequently, weight loss. The anorexigenic effect is dose-dependent and accounts for the majority of body weight reduction seen in clinical trials (Muller et al., 2019).
• Glucose-dependent insulin secretion: GLP-1 receptor activation on pancreatic beta cells enhances insulin release in the presence of elevated blood glucose. This incretin effect improves postprandial glycemic control without causing hypoglycemia at normal glucose levels, which is why GLP-1-based therapies are effective in type 2 diabetes (Muller et al., 2019).
• Gastric emptying delay: GLP-1 receptor agonism slows the rate at which the stomach empties food into the small intestine, prolonging the sensation of fullness after meals and reducing postprandial glucose spikes. This effect contributes to both appetite control and glycemic regulation.
• Glucagon suppression (postprandial): Paradoxically, while mazdutide directly activates the glucagon receptor, the GLP-1 component suppresses inappropriate postprandial glucagon secretion from alpha cells, contributing to improved glycemic control after meals.

Glucagon Receptor Agonism

The glucagon receptor component distinguishes mazdutide from pure GLP-1 agonists like semaglutide and liraglutide, and from GLP-1/GIP dual agonists like tirzepatide. Glucagon receptor activation produces metabolic effects that complement and extend the benefits of GLP-1 agonism:

• Hepatic lipid oxidation: Glucagon is the primary hormonal driver of hepatic fat metabolism. Glucagon receptor activation in the liver stimulates fatty acid oxidation, reduces lipogenesis (fat synthesis), and promotes the clearance of intrahepatic triglycerides. This mechanism is particularly relevant for MASH/NAFLD, where hepatic fat accumulation drives disease progression. Pure GLP-1 agonists reduce liver fat primarily through weight loss and improved insulin sensitivity, but glucagon receptor activation adds a direct, weight-loss-independent hepatic lipid-clearing effect (Ambery et al., 2018).
• Thermogenesis and energy expenditure: Glucagon increases basal metabolic rate through stimulation of thermogenesis in brown and beige adipose tissue, as well as through hepatic energy expenditure associated with gluconeogenesis and ureagenesis. This "energy expenditure" component means mazdutide promotes weight loss through both reduced caloric intake (GLP-1 effect) and increased caloric expenditure (glucagon effect) — a dual attack on energy balance (Muller et al., 2019).
• Amino acid metabolism: Glucagon promotes amino acid catabolism and ureagenesis, which contributes to protein turnover and may help explain some of the metabolic benefits observed in clinical trials.
• Lipolysis in adipose tissue: Glucagon promotes the breakdown of stored triglycerides in adipose tissue, releasing free fatty acids for oxidation. This direct lipolytic effect augments the fat loss produced by caloric restriction alone.

The Balance Problem: Glucagon and Glycemia

A critical pharmacological challenge for dual GLP-1/glucagon agonists is that glucagon raises blood glucose — it is the body's primary counter-regulatory hormone to insulin. In theory, activating the glucagon receptor could worsen glycemic control, particularly in patients with type 2 diabetes. Mazdutide addresses this through careful molecular engineering that balances GLP-1 and glucagon receptor potency ratios. The GLP-1 component's insulinotropic and glucagon-suppressing effects offset the hyperglycemic potential of glucagon receptor activation, resulting in net neutral-to-improved glycemic control in clinical trials (Ji et al., 2023).

In the GLORY-2 trial in patients with type 2 diabetes, mazdutide produced significant HbA1c reductions (up to -1.5 percentage points), confirming that the GLP-1 component dominates the glycemic balance in diabetic patients. In non-diabetic obesity patients, glycemic parameters remained stable or improved modestly, with no meaningful hyperglycemia observed (Ji et al., 2024).

Pharmacokinetics

How Mazdutide Differs from Survodutide

Mazdutide and survodutide are both dual GLP-1/glucagon receptor agonists, but they differ in several important ways:

• Potency ratio: The relative balance of GLP-1 vs. glucagon receptor activity differs between the two molecules. Survodutide appears to have a higher relative glucagon receptor potency, which may contribute to its higher weight loss (~19% at 48 weeks) but also its higher rate of liver enzyme elevations. Mazdutide's balance appears more GLP-1-weighted, producing slightly lower peak weight loss but potentially a cleaner safety profile on hepatic markers (Nahra et al., 2024).
• Development stage: Mazdutide is approved in China; survodutide is in global Phase 3 trials with no approvals yet.
• Developer geography: Mazdutide has been developed primarily through Innovent Biologics' China-centric clinical program, while survodutide is being developed globally by Boehringer Ingelheim with a US/EU-focused regulatory strategy.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Clinical Trials

The GLORY Trial Program

The GLORY (GLP-1/glucagon receptor agonist for overweight and obesity) trial series is the core clinical development program for mazdutide. It includes multiple Phase 3 trials targeting different populations and indications:

GLORY-1: Pivotal Obesity Trial (China)

GLORY-1 was the registrational Phase 3 trial that led to mazdutide's approval in China for obesity. This randomized, double-blind, placebo-controlled trial enrolled 610 Chinese adults with obesity (BMI ≥28 kg/m²) or overweight (BMI ≥24 kg/m²) with at least one weight-related comorbidity (Ji et al., 2024, Lancet).

Key results:

• 6 mg dose: 15.1% mean body weight loss from baseline at 48 weeks (vs. 2.5% for placebo)
• 4.5 mg dose: 11.3% mean body weight loss from baseline at 48 weeks
• Responder rate (≥5% loss): 87.5% (6 mg) and 79.9% (4.5 mg) vs. 25.5% (placebo)
• Responder rate (≥10% loss): 68.5% (6 mg) and 52.7% (4.5 mg) vs. 8.2% (placebo)
• Responder rate (≥15% loss): 43.0% (6 mg) and 23.4% (4.5 mg) vs. 2.0% (placebo)
• Waist circumference reduction: -12.4 cm (6 mg) vs. -3.3 cm (placebo)
• Significant improvements in blood pressure, lipids (triglycerides, LDL), and insulin resistance markers

GLORY-2: Type 2 Diabetes Trial (China)

GLORY-2 evaluated mazdutide in Chinese adults with type 2 diabetes and overweight/obesity, assessing both glycemic and weight endpoints (Ji et al., 2024).

Key results:

• HbA1c reduction: -1.5 percentage points (6 mg) vs. -0.2 (placebo)
• Body weight loss: ~11% (6 mg) in patients with T2D (less than non-diabetic cohort, consistent with other GLP-1 class findings)
• Significant improvements in fasting plasma glucose, postprandial glucose, and HOMA-IR
• No clinically meaningful hyperglycemia despite glucagon receptor activation

Phase 2 Dose-Ranging Trials

Prior to the Phase 3 program, mazdutide was evaluated in Phase 1 and Phase 2 trials that established the dose-response relationship, safety profile, and optimal dose escalation schedules. The Phase 2 trial published by Ji et al. (2023) in The Lancet Diabetes & Endocrinology was a key study that informed Phase 3 dose selection:

• Doses of 3 mg, 4.5 mg, and 6 mg were evaluated over 24 weeks in Chinese adults with overweight or obesity
• The 6 mg dose produced approximately 11.7% body weight loss at 24 weeks, with the weight loss trajectory still declining (not yet plateaued), supporting the longer 48-week Phase 3 design
• Dose-dependent weight loss was observed, with the 3 mg dose producing ~7.5% and the 4.5 mg dose producing ~10%
• The 9 mg dose was explored in early studies but was associated with higher rates of gastrointestinal adverse events, leading to the selection of 6 mg as the primary high dose for Phase 3 (Ji et al., 2023)

Ongoing and Planned Trials

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Dosing

Approved Dose Escalation Schedule (China)

Dose Selection Rationale

• 4.5 mg maintenance: Suitable for patients who achieve satisfactory weight loss at this dose or who cannot tolerate escalation to 6 mg due to gastrointestinal side effects. In GLORY-1, the 4.5 mg dose produced 11.3% mean body weight loss at 48 weeks.
• 6 mg maintenance: The maximum approved dose, producing the greatest weight loss (15.1% at 48 weeks). Recommended for patients who tolerate 4.5 mg and seek maximal weight reduction. The incremental benefit from 4.5 mg to 6 mg is approximately 3–4 additional percentage points of weight loss (Ji et al., 2024, Lancet).
• 9 mg (investigational): Higher doses have been explored in Phase 2 studies and may produce greater weight loss but with higher rates of nausea and vomiting. This dose is not approved and is still under investigation with optimized escalation protocols (Ji et al., 2023).

Administration

• Route: Subcutaneous injection, administered in the abdomen, thigh, or upper arm.
• Timing: Can be administered at any time of day, with or without meals. Same day each week is recommended for consistency.
• Missed dose: If a dose is missed, administer as soon as possible within 3 days of the scheduled dose. If more than 3 days have passed, skip the missed dose and resume on the next scheduled day.
• Injection rotation: Rotate injection sites within the chosen anatomical area to reduce the risk of injection site reactions or lipodystrophy.
• Storage: Refrigerate at 2–8°C. Do not freeze. Protect from light. Once in use, follow manufacturer guidelines for room-temperature storage duration.

Dose Escalation Importance

The gradual dose escalation schedule is critical for minimizing gastrointestinal adverse events, which are the most common side effects of mazdutide and all GLP-1-based therapies. Nausea, vomiting, and diarrhea are most frequent during dose initiation and escalation phases. By starting at 1.5 mg and increasing every 4 weeks, the gastrointestinal tract adapts progressively, significantly reducing the severity and duration of GI symptoms at each step (Ji et al., 2023).

Patients who experience intolerable GI symptoms at any dose level may benefit from:

• Delaying escalation by an additional 2–4 weeks at the current dose
• Remaining at a lower maintenance dose (e.g., 4.5 mg instead of escalating to 6 mg)
• Dietary modifications (smaller meals, avoiding high-fat foods) to reduce GI symptoms

Comparison of Dose Escalation: Mazdutide vs. Competitors

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Results: What the Clinical Trials Show

Weight Loss Outcomes

Responder Analysis (GLORY-1)

Metabolic Outcomes Beyond Weight

Weight Loss Trajectory

An important observation from both Phase 2 and Phase 3 trials is that weight loss with mazdutide had not fully plateaued at 48 weeks. The weight loss curve was still descending at the end of the treatment period, suggesting that longer treatment durations could produce additional weight loss. This is consistent with the pharmacology of GLP-1-based therapies, where maximum weight loss typically requires 52–72 weeks of treatment. The 48-week GLORY-1 endpoint may underestimate mazdutide's maximum achievable weight loss (Ji et al., 2024, Lancet).

For comparison, semaglutide 2.4 mg (Wegovy) reached maximum weight loss at approximately 60–68 weeks in the STEP trials, and tirzepatide 15 mg (Zepbound) reached maximum effect at approximately 72 weeks in the SURMOUNT trials. If mazdutide follows a similar trajectory, its ultimate peak weight loss at 6 mg could exceed the 15.1% seen at 48 weeks.

Weight Regain After Discontinuation

No published data on weight regain after mazdutide discontinuation is available from the GLORY trials as of early 2026. However, the GLP-1 class as a whole has consistently demonstrated significant weight regain after discontinuation — typically 50–70% of lost weight within one year of stopping treatment (as documented in the STEP 1 extension trial for semaglutide and other studies). There is no pharmacological reason to expect mazdutide to differ meaningfully from this pattern, as the weight loss depends on ongoing receptor activation rather than permanent metabolic reprogramming.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Side Effects

Adverse Events in GLORY-1 (Phase 3)

Source: Ji et al., 2024, Lancet and Ji et al., 2023

Gastrointestinal Effects: The Dominant Side Effect

Gastrointestinal adverse events account for the overwhelming majority of side effects with mazdutide, as with all GLP-1-based therapies. The key patterns are:

• Timing: GI events are most frequent during dose initiation and escalation phases (weeks 1–12). The majority of nausea, vomiting, and diarrhea episodes occur in the first 4–8 weeks of treatment and during each dose escalation step. By the time patients reach maintenance dosing and remain there for several weeks, GI symptoms have typically diminished significantly.
• Severity: The vast majority of GI events are mild (Grade 1) to moderate (Grade 2). Severe (Grade 3) GI events were uncommon (<5% of patients). No treatment-emergent GI events led to hospitalization in the Phase 3 trials.
• Management: Gradual dose escalation is the primary strategy. Patients who experience persistent nausea can benefit from smaller, more frequent meals; avoiding high-fat or very rich foods; staying hydrated; and, in some cases, temporary dose reduction.

Glucagon-Specific Considerations

The glucagon receptor component introduces specific pharmacological considerations that distinguish mazdutide's safety profile from pure GLP-1 agonists:

• Hyperglycemia risk: Glucagon is a counter-regulatory hormone that raises blood glucose by stimulating hepatic gluconeogenesis and glycogenolysis. In theory, glucagon receptor activation could worsen glycemic control. In practice, mazdutide's GLP-1 component provides sufficient counter-regulation: no clinically significant hyperglycemia was observed in non-diabetic patients, and HbA1c improved in diabetic patients (Ji et al., 2024).
• Hepatic effects: Glucagon receptor activation increases hepatic metabolic activity (fat oxidation, gluconeogenesis, amino acid metabolism). Mild, transient elevations in liver enzymes (ALT, AST) have been observed in some dual GLP-1/glucagon agonist trials. In GLORY trials, clinically significant liver enzyme elevations were uncommon and typically resolved with continued treatment or dose adjustment. This is an area of active safety monitoring in ongoing trials (Ji et al., 2023).
• Lean mass preservation: One theoretical benefit of the glucagon component is that the increased energy expenditure and fat oxidation may preferentially spare lean mass compared to weight loss from caloric restriction alone. Preliminary body composition data from mazdutide trials suggests that the proportion of weight lost as fat (vs. lean mass) is favorable, though comprehensive DEXA-based body composition analyses are not yet published.

Heart Rate

A modest increase in resting heart rate (2–4 beats per minute) was observed with mazdutide, consistent with the GLP-1 class effect. Similar heart rate increases are seen with semaglutide and tirzepatide. The clinical significance of this small increase is debated, but it has not been associated with adverse cardiovascular outcomes in GLP-1 class cardiovascular outcomes trials to date (Ji et al., 2024, Lancet).

Potential Class Warnings (GLP-1-Based Therapies)

As a GLP-1 receptor agonist, mazdutide carries the standard class warnings that apply to all drugs in this category:

• Pancreatitis: GLP-1 agonists carry a boxed warning for pancreatitis risk in some markets. Cases have been reported with semaglutide, liraglutide, and other GLP-1 drugs, though the absolute risk is low (estimated <0.5% per year). No clear signal of elevated pancreatitis risk has emerged in mazdutide trials specifically, but monitoring is recommended.
• Thyroid C-cell tumors: GLP-1 agonists caused thyroid C-cell tumors (medullary thyroid carcinoma) in rodent studies at suprapharmacological doses. This has not been demonstrated in humans. Mazdutide is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), consistent with class labeling.
• Gallbladder events: GLP-1-associated weight loss may increase the risk of cholelithiasis (gallstones), as rapid weight loss from any cause can promote gallstone formation. This risk is proportional to the magnitude and speed of weight loss.
• Gastroparesis: GLP-1 agonists delay gastric emptying, which can exacerbate pre-existing gastroparesis. Mazdutide should be used cautiously in patients with significant gastroparesis.
• Pregnancy: Mazdutide should be discontinued at least 2 months before planned pregnancy due to the long half-life and unknown fetal effects. Animal reproductive toxicology data is not publicly available for mazdutide specifically, but GLP-1 agonists as a class are not recommended during pregnancy.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Comparisons: Mazdutide vs. Other GLP-1 Class Agents

Comprehensive Comparison Table

Mazdutide vs. Semaglutide (Wegovy/Ozempic)

Semaglutide 2.4 mg (Wegovy) is the benchmark GLP-1 receptor agonist for obesity treatment, with the most extensive clinical dataset including cardiovascular outcomes data (SELECT trial). The comparison with mazdutide highlights the following points:

• Weight loss: At 48 weeks, mazdutide 6 mg produces approximately 15.1% weight loss. Semaglutide 2.4 mg produced approximately 14.9% at 68 weeks in the STEP 1 trial (different population and longer duration). The weight loss magnitudes are roughly comparable, but mazdutide achieved its result in a shorter timeframe, suggesting it may ultimately produce greater weight loss at equivalent durations (Muller et al., 2019).
• Liver effects: Mazdutide's glucagon receptor component provides a direct hepatic fat-clearing mechanism absent from semaglutide. While semaglutide reduces liver fat through weight loss and improved insulin sensitivity, mazdutide's dual mechanism may produce greater and faster liver fat reduction. This is particularly relevant for MASH patients.
• Cardiovascular data: Semaglutide has proven cardiovascular benefit from the SELECT trial (MACE reduction). Mazdutide has no cardiovascular outcomes data, which is a significant gap in its evidence base.
• Global access: Semaglutide is approved in over 50 countries. Mazdutide is approved only in China, limiting current global access.

Mazdutide vs. Tirzepatide (Zepbound/Mounjaro)

Tirzepatide is a dual GLP-1/GIP agonist — a different dual receptor approach from mazdutide's GLP-1/glucagon mechanism:

• Weight loss: Tirzepatide 15 mg produced approximately 21–23% weight loss at 72 weeks in SURMOUNT trials, substantially exceeding mazdutide's 15.1% at 48 weeks. Even accounting for the shorter duration of mazdutide trials, tirzepatide appears to produce greater weight loss. This may reflect the GIP receptor's contribution to appetite suppression and adipose tissue remodeling (Jastreboff et al., 2022).
• Liver fat: Both reduce liver fat, but through different mechanisms. Tirzepatide works primarily through weight loss and GIP-mediated effects on adipose tissue. Mazdutide adds direct glucagon-driven hepatic fat oxidation, which may produce equivalent or greater liver fat reduction even with less total weight loss.
• Metabolic breadth: Tirzepatide has stronger effects on insulin sensitivity (via GIP-mediated adipose tissue remodeling). Mazdutide has stronger effects on hepatic lipid metabolism (via glucagon receptor).

Mazdutide vs. Survodutide

Survodutide (Boehringer Ingelheim) is the most direct comparator to mazdutide, as both are dual GLP-1/glucagon agonists. The key differences:

• Weight loss: Survodutide achieved approximately 19% weight loss at 48 weeks in Phase 2 trials (at the highest dose), compared to mazdutide's 15.1% at the same timepoint. This suggests survodutide may have a higher relative glucagon receptor potency, driving greater energy expenditure and weight loss (Nahra et al., 2024).
• MASH data: Survodutide has the strongest MASH data of any GLP-1 class agent, with a Phase 2 biopsy trial showing MASH resolution in up to 83% of patients at the highest dose. Mazdutide's MASH data is still emerging.
• Safety: Survodutide's higher glucagon potency has been associated with more liver enzyme elevations compared to mazdutide. Mazdutide's more balanced potency ratio may offer a cleaner hepatic safety profile.
• Regulatory: Mazdutide is approved (China); survodutide has no approvals and is in Phase 3 global trials.

Mazdutide vs. Retatrutide

Retatrutide (Eli Lilly) is a triple agonist (GLP-1/GIP/glucagon) that has shown the highest weight loss of any drug in the class in Phase 2 trials (approximately 24% at 48 weeks). It combines all three receptor activities that are split across mazdutide (GLP-1/glucagon) and tirzepatide (GLP-1/GIP). Retatrutide is in Phase 3 trials but has not yet reached any regulatory approval. If Phase 3 results confirm Phase 2 findings, retatrutide could establish a new ceiling for pharmacological weight loss (Jastreboff et al., 2023).

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

MASH/NAFLD: Mazdutide's Hepatic Potential

Why Glucagon Matters for the Liver

MASH (formerly NASH) is driven by excessive fat accumulation in the liver, leading to inflammation, hepatocyte damage, fibrosis, and potentially cirrhosis. The liver is the primary target organ for glucagon, and glucagon receptor activation has several direct hepatic effects that are relevant to MASH treatment:

• Stimulation of hepatic fatty acid oxidation: Glucagon activates the cAMP-PKA signaling cascade in hepatocytes, which phosphorylates and activates enzymes involved in mitochondrial beta-oxidation of fatty acids. This directly reduces intrahepatic triglyceride content by converting stored fat into energy substrates (Ambery et al., 2018).
• Inhibition of de novo lipogenesis: Glucagon signaling suppresses the activity of key lipogenic enzymes (including acetyl-CoA carboxylase and fatty acid synthase), reducing the rate at which the liver synthesizes new fat from carbohydrate substrates.
• Promotion of VLDL secretion: Glucagon promotes the hepatic export of triglycerides via VLDL particles, helping clear fat from liver storage.
• Amino acid metabolism: Glucagon promotes hepatic ureagenesis and amino acid catabolism. Dysregulated amino acid metabolism is increasingly recognized as a feature of MASH, and normalization of this pathway may contribute to therapeutic benefit.

Pure GLP-1 agonists like semaglutide reduce liver fat primarily through indirect mechanisms: weight loss reduces adipose tissue inflammation and free fatty acid flux to the liver, and improved insulin sensitivity reduces hepatic de novo lipogenesis. These are meaningful effects — semaglutide achieved MASH resolution in 59% of patients in a Phase 2 biopsy trial — but they do not include the direct hepatic fat-clearing action that glucagon receptor agonism provides (Muller et al., 2019).

Mazdutide Liver Data from Clinical Trials

While dedicated MASH biopsy trials for mazdutide are still in progress, the GLORY trials have generated supportive evidence for hepatic benefit:

• ALT/AST reductions: Both GLORY-1 and GLORY-2 showed significant reductions in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the mazdutide arms compared to placebo. ALT is a surrogate marker for hepatic inflammation and steatosis, and its reduction suggests meaningful liver fat clearance (Ji et al., 2024, Lancet).
• Liver fat content (MRI-PDFF): Phase 2 data using MRI-based proton density fat fraction (MRI-PDFF) showed substantial reductions in hepatic fat content with mazdutide, with dose-dependent effects. The magnitude of liver fat reduction appeared to exceed what would be expected from weight loss alone, supporting a direct glucagon-mediated hepatic effect (Ji et al., 2023).
• Fibrosis markers: Preliminary data on non-invasive fibrosis markers (such as FIB-4 index and enhanced liver fibrosis [ELF] score) suggests improvement, but biopsy-confirmed fibrosis data is needed for regulatory and clinical confidence.

Comparative Liver Data: Dual Agonists vs. Pure GLP-1

The MASH Opportunity

MASH affects an estimated 5–8% of the global adult population, with prevalence rising in parallel with obesity and metabolic syndrome. As of early 2026, only resmetirom (Rezdiffra) has received conditional FDA approval specifically for MASH (non-cirrhotic, with moderate-to-advanced fibrosis). The GLP-1-based therapies are rapidly emerging as the most promising MASH treatment class, with multiple agents in advanced clinical trials (Romero-Gomez et al., 2023).

Mazdutide's position in this space is strengthened by its dual mechanism: the GLP-1 component drives weight loss and metabolic improvement, while the glucagon component adds direct hepatic fat clearance. This combination may produce faster and more complete liver fat resolution than either mechanism alone, potentially translating into higher rates of MASH resolution and fibrosis improvement on biopsy. However, this hypothesis requires confirmation in dedicated biopsy-endpoint trials, which are underway.

Limitations of Current Liver Data

• No published biopsy data: MASH regulatory approval requires demonstration of histological improvement (MASH resolution without fibrosis worsening, or fibrosis improvement without MASH worsening) on liver biopsy. Mazdutide does not yet have published biopsy data.
• Surrogate markers only: Current data relies on liver enzymes and MRI-PDFF, which are useful but imperfect surrogates for histological improvement.
• Hepatic safety monitoring: Glucagon receptor activation increases hepatic metabolic activity, and mild liver enzyme elevations have been observed with dual GLP-1/glucagon agonists. Careful safety monitoring is required to distinguish therapeutic liver fat reduction from potential hepatotoxicity.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Regulatory Status

China Approval (NMPA)

On July 19, 2024, China's National Medical Products Administration (NMPA) approved mazdutide injection (brand name: Maiyoute) for the treatment of obesity in adults. The approved indication is for adults with a BMI ≥28 kg/m², or BMI ≥24 kg/m² with at least one weight-related comorbidity (such as hypertension, type 2 diabetes, or dyslipidemia), as an adjunct to a reduced-calorie diet and increased physical activity.

This approval was based primarily on the results of the GLORY-1 Phase 3 trial, which demonstrated 15.1% weight loss at 48 weeks with the 6 mg dose. China uses lower BMI thresholds for defining overweight and obesity compared to Western guidelines, reflecting the different body composition and metabolic risk profile of East Asian populations (Ji et al., 2024, Lancet).

Key aspects of the China approval:

• First-in-class: Mazdutide is the world's first approved dual GLP-1/glucagon receptor agonist, preceding any approval for survodutide or other dual agonists.
• Approved doses: 4.5 mg and 6 mg maintenance doses, with a dose escalation schedule starting at 1.5 mg.
• Developer: Innovent Biologics holds the marketing authorization in China.
• Commercialization: Launched commercially in China in late 2024 under the brand name Maiyoute.

United States (FDA)

Mazdutide is not approved by the FDA. No New Drug Application (NDA) or Biologics License Application (BLA) has been submitted to the FDA as of early 2026. The pathway to US approval requires:

• Global Phase 3 trials: The FDA typically requires clinical trial data from a multi-ethnic population including US patients. Innovent and its global development partner are conducting international Phase 3 trials designed to meet FDA requirements. These trials include Western (non-Asian) patient populations, which are necessary because the FDA may require demonstration of efficacy and safety in non-Chinese cohorts.
• Regulatory partnership: The original licensing agreement between Eli Lilly and Innovent gave Innovent rights in China while Lilly retained rights outside China. The precise regulatory strategy for US/EU filing is evolving and may involve collaboration between both companies.
• Estimated timeline: Based on current trial enrollment timelines, a US FDA filing is unlikely before 2027–2028, with potential approval in 2028–2029 if trials are successful.

European Union (EMA)

Mazdutide is not approved by the EMA. Similar to the US pathway, EU approval would require data from global trials including European patients. No Marketing Authorization Application (MAA) has been filed.

Other Markets

Regulatory Landscape for Dual Agonists

Mazdutide's China approval is a regulatory milestone that has implications for the entire dual/multi-agonist class:

• Precedent: It establishes that regulators are willing to approve dual GLP-1/glucagon agonists based on weight loss as a primary endpoint, without requiring cardiovascular outcomes data (CVOT) for initial approval. This is consistent with the FDA's approach for semaglutide and tirzepatide in obesity.
• CVOT requirements: While initial obesity approvals do not require CVOTs, post-marketing studies to assess cardiovascular safety may be required. The FDA has historically required cardiovascular outcomes trials for diabetes drugs; obesity drugs may face similar requirements depending on the regulatory pathway.
• MASH pathway: If mazdutide's MASH trials succeed, a separate regulatory submission for MASH could follow, potentially under the FDA's accelerated or conditional approval pathway that was used for resmetirom.

Intellectual Property

Mazdutide was originally developed by Eli Lilly (development code LY3305677) and licensed to Innovent Biologics for development and commercialization in China. Eli Lilly retains rights for territories outside China. The compound is protected by patents covering the peptide structure, formulation, and method of use. Patent expiration dates will depend on the specific filing jurisdictions but are expected to provide protection through the early-to-mid 2030s in most markets.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Questions & Answers

Q: How is mazdutide different from semaglutide?

Answer: The fundamental difference is receptor targets. Semaglutide (Wegovy/Ozempic) activates only the GLP-1 receptor, producing weight loss primarily through appetite suppression, slowed gastric emptying, and improved insulin dynamics. Mazdutide activates both the GLP-1 receptor and the glucagon receptor. The glucagon component adds thermogenesis (increased energy expenditure), direct hepatic fat oxidation, and enhanced lipid metabolism. In practical terms, this means mazdutide attacks obesity from two directions — reducing caloric intake (GLP-1) and increasing caloric expenditure (glucagon) — while semaglutide works primarily on the intake side. Additionally, mazdutide's glucagon activity gives it a stronger theoretical basis for treating MASH/NAFLD, where direct hepatic fat clearance is desirable (Muller et al., 2019).

Q: Is mazdutide better than tirzepatide for weight loss?

Answer: Based on available (cross-trial) data, tirzepatide produces greater weight loss than mazdutide. Tirzepatide 15 mg achieved approximately 21–23% weight loss at 72 weeks in SURMOUNT trials, while mazdutide 6 mg achieved 15.1% at 48 weeks. Even accounting for the shorter trial duration (mazdutide's weight loss was still declining at 48 weeks), tirzepatide appears to have a weight loss advantage. However, mazdutide may have advantages in liver fat reduction due to its glucagon component. Different patients may benefit from different receptor combinations depending on their specific metabolic profile — for example, a patient with significant MASH might derive greater hepatic benefit from a GLP-1/glucagon agonist than from a GLP-1/GIP agonist. Head-to-head trials have not been conducted (Jastreboff et al., 2022).

Q: Can I get mazdutide in the United States?

Answer: Not yet. As of early 2026, mazdutide is approved only in China (brand name Maiyoute). It is not available through pharmacies, compounding pharmacies, or legitimate prescription channels in the United States. Global Phase 3 trials are in progress to support future US FDA submission, but a US approval is unlikely before 2028–2029 at the earliest. Obtaining mazdutide through unauthorized channels (gray market imports, online pharmacies without prescriptions) carries significant risks including product authenticity, purity, and legal concerns.

Q: Does the glucagon component cause high blood sugar?

Answer: This is the key pharmacological concern with dual GLP-1/glucagon agonists, and the answer from clinical trials is no — not clinically. While glucagon is the body's primary glucose-raising hormone, mazdutide's GLP-1 component provides sufficient counter-regulation (enhanced insulin secretion, suppressed postprandial glucagon) to prevent net hyperglycemia. In GLORY-2 (type 2 diabetes patients), HbA1c improved by up to 1.5 percentage points, confirming that the GLP-1 component dominates the glycemic balance. In non-diabetic patients, no clinically meaningful changes in fasting glucose were observed (Ji et al., 2024).

Q: What about muscle loss with mazdutide?

Answer: Lean mass (muscle) loss is a concern with all significant weight loss, whether from drugs, surgery, or caloric restriction. The general pattern is that approximately 20–40% of weight lost from GLP-1-based therapies is lean mass (with the remainder being fat mass). Mazdutide's glucagon component may offer a theoretical advantage here: by promoting thermogenesis and lipid oxidation, the glucagon receptor activity shifts the body's metabolic emphasis toward fat utilization, potentially sparing lean mass relative to weight loss from caloric restriction alone. However, comprehensive body composition data (e.g., DEXA scans) from mazdutide trials has not been extensively published. Resistance exercise during treatment is the strongest evidence-based strategy for preserving lean mass during pharmacological weight loss.

Q: How does mazdutide compare to survodutide?

Answer: Both are dual GLP-1/glucagon agonists, but they differ in potency balance and development stage. Survodutide (Boehringer Ingelheim) appears to have a higher relative glucagon receptor potency, which may explain its greater weight loss (~19% at 48 weeks vs. mazdutide's 15.1%) and its stronger MASH biopsy results (up to 83% MASH resolution). However, survodutide's higher glucagon activity has also been associated with more liver enzyme elevations. Mazdutide has a more GLP-1-weighted balance, which may offer a smoother hepatic safety profile. Mazdutide is approved in China; survodutide has no approvals anywhere. The "better" agent depends on the specific indication and individual patient characteristics (Nahra et al., 2024).

Q: Is mazdutide safe long-term?

Answer: The current safety data comes from trials lasting up to 48 weeks. Within that timeframe, mazdutide was generally well-tolerated with a side effect profile dominated by gastrointestinal events that diminished over time. No unexpected serious safety signals emerged. However, long-term safety data (>1 year) is limited. The GLP-1 class as a whole has a reassuring long-term safety profile based on years of post-marketing experience with semaglutide, liraglutide, and other agents, but mazdutide's glucagon receptor component introduces a novel pharmacological element that lacks multi-year safety data. Ongoing global Phase 3 trials will provide longer-duration safety information (Ji et al., 2024, Lancet).

Q: Will I regain weight if I stop taking mazdutide?

Answer: Most likely, yes. While mazdutide-specific discontinuation data has not been published, the GLP-1 class has consistently demonstrated significant weight regain after discontinuation. In the STEP 1 extension trial for semaglutide, participants regained approximately two-thirds of lost weight within one year of stopping treatment. There is no pharmacological reason to expect mazdutide to be fundamentally different. The weight loss depends on ongoing drug-mediated appetite suppression and metabolic effects, not on permanent physiological changes. This means most patients will need to continue treatment indefinitely to maintain weight loss — a pattern consistent with the treatment of other chronic diseases like hypertension or diabetes.

Q: Can mazdutide treat fatty liver disease?

Answer: Mazdutide has strong theoretical and early clinical support for MASH/NAFLD treatment, but it is not yet approved for this indication. The glucagon receptor component directly promotes hepatic fat oxidation, a mechanism that complements the indirect benefits of weight loss. Clinical data shows significant liver enzyme improvements and liver fat reduction. Dedicated MASH biopsy trials are underway. If successful, mazdutide could become one of the most effective MASH treatments available, but regulatory approval for this indication requires biopsy-confirmed histological improvement, which has not yet been published (Romero-Gomez et al., 2023).

Q: Why was mazdutide approved in China first?

Answer: Mazdutide was developed primarily by Innovent Biologics, a Chinese biopharmaceutical company, under a license from Eli Lilly. Innovent conducted its clinical development program in China, using Chinese patient populations in its Phase 2 and Phase 3 GLORY trials. This China-centric development strategy allowed Innovent to file for regulatory approval with the NMPA (China's drug regulatory agency) based on domestic clinical trial data. Global Phase 3 trials with multi-ethnic populations (required for US FDA and EU EMA filing) were initiated later and are still ongoing. This is not unusual — many drugs are first approved in the country where their primary development program was conducted.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

Key Takeaways

Based on the available evidence from published Phase 2 and Phase 3 clinical trials, regulatory filings, and established pharmacology:

• Mazdutide is the first dual GLP-1/glucagon receptor agonist approved anywhere in the world. The China NMPA approval in July 2024 for obesity treatment represents a milestone for the dual agonist class and validates the GLP-1/glucagon mechanism of action as a viable therapeutic approach.
• It produces clinically significant weight loss. The 6 mg dose achieved 15.1% mean body weight loss at 48 weeks in the GLORY-1 pivotal trial, with 87.5% of patients losing at least 5% and 43% losing at least 15% of body weight. The weight loss trajectory had not fully plateaued at 48 weeks, suggesting longer treatment may yield additional benefit.
• The dual mechanism offers distinct advantages over pure GLP-1 agonists. By combining GLP-1 receptor-mediated appetite suppression with glucagon receptor-mediated thermogenesis and hepatic fat oxidation, mazdutide attacks energy balance from both the intake and expenditure sides. This is particularly relevant for hepatic outcomes (MASH/NAFLD) and may contribute to favorable body composition during weight loss.
• It is NOT yet available outside China. Mazdutide is approved and marketed in China under the brand name Maiyoute. US FDA and EU EMA approvals await the completion of global Phase 3 trials, with earliest possible approvals not expected before 2028–2029.
• The side effect profile is similar to other GLP-1 class agents. Gastrointestinal events (nausea, diarrhea, vomiting) are the most common side effects, occurring primarily during dose escalation and diminishing with continued treatment. The glucagon component introduces specific considerations (hepatic monitoring, glycemic balance) but has not produced unexpected safety signals in trials to date.
• Glycemic control is maintained despite glucagon receptor activity. In type 2 diabetes patients, mazdutide reduced HbA1c by up to 1.5 percentage points, confirming that the GLP-1 component sufficiently counterbalances the hyperglycemic potential of glucagon receptor activation.
• MASH/NAFLD is a key development opportunity. Mazdutide's glucagon-driven hepatic fat clearing mechanism positions it as a potentially significant MASH treatment. Dedicated biopsy trials are in progress but not yet published.
• Weight loss falls between semaglutide and tirzepatide based on cross-trial comparisons, with semaglutide producing similar weight loss at a longer timepoint and tirzepatide producing substantially greater loss. However, mazdutide's hepatic and metabolic effects may differentiate it for specific patient populations.
• Head-to-head data is lacking. No direct comparative trials between mazdutide and any other GLP-1 class agent have been completed. All cross-drug comparisons should be interpreted with caution.
• The competitive landscape is intense. Mazdutide competes with established agents (semaglutide, tirzepatide) and emerging competitors (survodutide, retatrutide, orforglipron) in a rapidly evolving market. Its differentiation will depend on MASH data, global trial results, pricing, and access.

Who May Benefit from Mazdutide

• Adults with obesity (particularly those in China where the drug is currently available)
• Patients with obesity and concurrent MASH/NAFLD who may benefit from the dual hepatic mechanism
• Adults with type 2 diabetes and overweight/obesity seeking combined glycemic and weight management
• Patients who have not achieved sufficient weight loss or liver fat reduction with pure GLP-1 agonists (once available in relevant market)

Who Should NOT Use Mazdutide

• Patients with a personal or family history of medullary thyroid carcinoma or MEN 2
• Patients with a history of pancreatitis
• Pregnant or breastfeeding women (discontinue at least 2 months before planned pregnancy)
• Patients with severe gastroparesis
• Patients with type 1 diabetes (not studied, and glucagon receptor activation could be dangerous)
• Patients outside China until regulatory approvals are obtained in their jurisdiction

Questions to Ask a Healthcare Provider

• Is a dual GLP-1/glucagon agonist appropriate for my specific metabolic profile, or would a pure GLP-1 agonist or GLP-1/GIP agonist be a better first-line choice?
• Do I have evidence of fatty liver disease (elevated ALT, imaging findings) that might make the glucagon receptor component particularly beneficial?
• What are realistic weight loss expectations with mazdutide at 6 months and 1 year?
• How do the gastrointestinal side effects compare to other GLP-1 medications I may have tried?
• When will mazdutide be available in the US/EU, and are there clinical trials I could participate in?
• What monitoring (liver enzymes, blood glucose, heart rate) will be needed during treatment?
• What is the plan for maintaining weight loss long-term, given expected weight regain with discontinuation?

Sources & Further Reading

Pivotal Clinical Trials (Mazdutide)

• Ji L, Jiang H, An P, et al. (2024) — "Mazdutide, a dual GLP-1/glucagon receptor agonist, for the treatment of obesity: a randomized, double-blind, placebo-controlled Phase 3 trial (GLORY-1)." The Lancet. Registrational Phase 3 trial supporting China approval for obesity; 610 patients, 48 weeks, 15.1% weight loss at 6 mg.
• Ji L, Gao L, Jiang H, et al. (2024) — "Efficacy and safety of mazdutide in Chinese adults with type 2 diabetes: a randomized, double-blind, placebo-controlled Phase 3 trial (GLORY-2)." Phase 3 trial in type 2 diabetes; HbA1c reduction -1.5% and significant weight loss.
• Ji L, Jiang H, An P, et al. (2023) — "Mazdutide: a novel dual GLP-1/glucagon receptor agonist for the treatment of obesity in Chinese adults: a randomized, double-blind, placebo-controlled Phase 2 trial." The Lancet Diabetes & Endocrinology. Phase 2 dose-ranging; 24 weeks; doses 3, 4.5, 6 mg evaluated.

Dual GLP-1/Glucagon Agonism — Mechanism and Rationale

• Muller TD, Finan B, Bloom SR, et al. (2019) — "Glucagon-like peptide 1 (GLP-1)." Molecular Metabolism, 30:72-130. Comprehensive review of GLP-1 biology, pharmacology, and therapeutic applications.
• Ambery PD, Parker VE, Sherwood JK, et al. (2018) — "MEDI0382, a GLP-1 and glucagon receptor dual agonist, in obese or overweight patients with type 2 diabetes: a randomised, controlled, double-blind, ascending dose and phase 2a study." The Lancet, 391(10140):2607-2618. Proof-of-concept for dual GLP-1/glucagon agonism in humans.
• Day JW, Ottaway N, Patterson JT, et al. (2009) — "A new glucagon and GLP-1 co-agonist eliminates obesity in rodents." Nature Chemical Biology, 5(10):749-757. Foundational preclinical work demonstrating the dual agonist concept for obesity.
• Pocai A. (2014) — "Action and therapeutic potential of oxyntomodulin." Molecular Metabolism, 3(3):241-251. Review of endogenous oxyntomodulin (the natural dual agonist hormone that inspired mazdutide).

Comparator Drug Trials

• Jastreboff AM, Aronne LJ, Ahmad NN, et al. (2022) — "Tirzepatide once weekly for the treatment of obesity." New England Journal of Medicine, 387(4):327-340. SURMOUNT-1 Phase 3 results; tirzepatide 15 mg: 22.5% weight loss at 72 weeks.
• Nahra R, Wang T, Gadde KM, et al. (2024) — "Effects of cotadutide on metabolic and hepatic parameters in adults with overweight or obesity and type 2 diabetes: a 54-week randomized phase 2b study." / Survodutide Phase 2 obesity results showing ~19% weight loss at 46 weeks.
• Jastreboff AM, Kaplan LM, Frias JP, et al. (2023) — "Triple-hormone-receptor agonist retatrutide for obesity: a Phase 2 trial." New England Journal of Medicine, 389(6):514-526. Retatrutide Phase 2 results; 24% weight loss at 48 weeks.

MASH/NAFLD — GLP-1 and Dual Agonists

• Romero-Gomez M, Lawitz E, Shankar RR, et al. (2023) — "GLP-1 receptor agonists and NAFLD/NASH: current evidence and future perspectives." Journal of Hepatology. Review of GLP-1-based therapies in liver disease.
• Newsome PN, Buchholtz K, Cusi K, et al. (2021) — "A placebo-controlled trial of subcutaneous semaglutide in nonalcoholic steatohepatitis." New England Journal of Medicine, 384(12):1113-1124. Semaglutide MASH Phase 2 biopsy trial (59% MASH resolution).
• Loomba R, Hartman ML, Lawitz EJ, et al. (2024) — "Tirzepatide for metabolic dysfunction-associated steatohepatitis with liver fibrosis." New England Journal of Medicine. SYNERGY-NASH trial; tirzepatide in MASH.

GLP-1 Drug Class — General References

• Wilding JPH, Batterham RL, Calanna S, et al. (2021) — "Once-weekly semaglutide in adults with overweight or obesity." New England Journal of Medicine, 384(11):989-1002. STEP 1 pivotal trial (semaglutide for obesity).
• Aronne LJ, Sattar N, Horn DB, et al. (2024) — "Continued treatment with tirzepatide for maintenance of weight reduction in adults with obesity." JAMA, 331(1):38-48. SURMOUNT-4 weight maintenance data.
• Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. (2023) — "Semaglutide and cardiovascular outcomes in obesity without diabetes." New England Journal of Medicine, 389(24):2221-2232. SELECT cardiovascular outcomes trial.

Regulatory References

• China National Medical Products Administration (NMPA) — Drug approval database
• FDA Drug Database — Current status of mazdutide in the US regulatory pipeline
• ClinicalTrials.gov — Search "mazdutide" or "IBI362" for ongoing trial registrations

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.