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Retatrutide

From PeptidePlaza, the free peptide reference · Entry #003 · Metabolic · Hand-curated entry · Editorial standards

Research warning. Currently an investigational new drug not yet approved for medical use. Demonstrates potent cardiovascular and metabolic alterations in clinical trials.

Retatrutide (also known as LY3437943) is a metabolic research peptide. A novel triple receptor agonist targeting GLP-1, GIP, and glucagon receptors simultaneously — the first of its kind in human Phase 2 trials. Early data suggests it may surpass dual agonists.

Retatrutide is a unimolecular triple agonist targeting glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon receptors. Adding glucagon receptor agonism to the GIP/GLP-1 dual mechanism theoretically increases energy expenditure via thermogenesis and hepatic fat mobilization, while the GLP-1 and GIP components manage appetite and insulin secretion. Phase 2 trial data (2023) showed up to 24.2% mean weight reduction at 48 weeks — the highest ever reported in a clinical obesity trial.

1 Mechanism of action

Triple receptor co-agonism: GLP-1R (appetite suppression, insulin secretion), GIPR (adipose lipolysis, insulin potentiation), GcgR (hepatic glucose output regulation, thermogenesis, lipolysis). The glucagon component drives energy expenditure not achieved by dual agonists.

Primary targets: GLP-1R · GIPR · GcgR

2 Reported effects

Effects below are those reported in the published literature cited on this page. They are not claims of clinical benefit and not medical advice.

2.1 Reported benefits

  • Highest recorded weight loss in clinical trials (24.2% at 48 weeks)
  • Dramatic reduction in hepatic fat (liver fat resolution in most subjects)
  • Increased resting energy expenditure
  • Comprehensive metabolic syndrome reversal

2.2 Side effects

  • Increased heart rate (transient)
  • Gastrointestinal side effects (nausea, diarrhea, constipation)
  • Skin hyperesthesia (increased sensitivity) in some subjects
  • Hypoglycemia risk if combined with insulin

3 Chemical and physical properties

CAS number2381089-83-2
Molar mass4731.33 g/mol
Purity (typical)>99.1%
Half-life~6 days (estimated)
Storage−20 °C, lyophilised powder, desiccated
SolubilitySterile water / bacteriostatic water
Receptors / targetsGLP-1R, GIPR, GcgR

4 Research dosages

1–12 mg SC once weekly (Phase 2 dose range); Phase 3 is evaluating 2–12 mg for obesity.

Dosages are reported from published protocols for reference only. Research chemicals are not for human consumption.

5 Research studies (8)

  1. Retatrutide, a GIP, GLP-1 and Glucagon Receptor Agonist, for People with Type 2 Diabetes
    The Lancet (2023) · RCT · N=281
    Phase 2 RCT. Dose-dependent weight reduction up to 22.8 kg at 24 weeks; HbA1c reduction of 2.02% at highest dose.
    Key finding: 22.8 kg weight loss and 2.02% HbA1c reduction at 24 weeks — unprecedented speed of metabolic improvement.
  2. Retatrutide Phase 2 Obesity Trial (NEJM)
    New England Journal of Medicine (2023) · RCT · N=338
    N=338. 24.2% mean weight reduction at 48 weeks for the 12 mg group — highest reported weight loss in any obesity RCT to date.
    Key finding: 24.2% mean weight loss — highest ever reported in an obesity RCT. Liver fat resolved in majority of subjects.
  3. Composition and Labelling Accuracy of Products Sold as Retatrutide in Australia
    Drug and alcohol review (2026) · Review
    Author information: (1)School of Public Health, Faculty of Health, Medicine and Behavioural Sciences, University of Queensland, Brisbane, Australia.
  4. Retatrutide effects on diabetic rats' cognition
    Lab animal (2026) · Preclinical
    tatrutide effects on diabetic rats' cognition. Ferreira J(1). Author information: (1)Lab Animal, . jorge.ferreira@springernature.com. DOI: 10.1038/s41684-026-01778-7 PMID: 42527705
  5. Retatrutide and the urinary tract infection signal: Is the answer hidden in timing?
    European journal of internal medicine (2026) · Review
    My Best Weight clinic and Beyond BMI clinic and is a co-owner of these clinics.
  6. Retatrutide fact check: Has a man died after taking the unapproved weight loss jab?
    BMJ (Clinical research ed.) (2026) · Review
    Retatrutide fact check: Has a man died after taking the unapproved weight loss jab?
  7. Effects of retatrutide on learning and memory in streptozotocin-induced male diabetic rats
    Behavioural brain research (2026) · Preclinical
    Further studies in insulin-resistant and type 2 diabetes-like models are needed to clarify the underlying mechanisms and translational relevance.
  8. Effect of Retatrutide, a Novel Triple Receptor Agonist, on Blood Pressure and Lipid Levels: A Systematic Review and Meta-analysis of Randomized Controlled Trials
    High blood pressure & cardiovascular prevention : the official journal of the Italian Society of Hypertension (2026) · Meta-Analysis
    The results of our meta-analysis revealed that retatrutide treatment decreases blood pressure and improves lipid profile by reducing total cholesterol, LDL-C, and triglyceride levels.

6 Safety and risk profile

6.1 Regulatory status

Retatrutide is currently classified as Phase 3 clinical trials. It has no approved human indication in the United States; availability elsewhere does not imply demonstrated safety or efficacy.

Safety score: 60/100 — moderate concern. Derived from clinical data volume, known risks and regulatory status.

6.2 Contraindications

Conditions and populations in which use is contraindicated:

  • Uncontrolled hypertension (due to heart rate increase)
  • History of tachyarrhythmias or prolonged QTc
  • Medullary thyroid carcinoma / MEN2
  • Pancreatitis history
  • Pregnancy

6.3 Drug interactions

Drug or classInteractionRisk
Beta-blockers / rate-control medicationsGlucagon agonism increases heart rate 3–5 bpm; may counteract rate-control therapy.Moderate
InsulinAdditive hypoglycemia risk from triple mechanism; insulin dose reduction of 20–40% may be needed.High

6.4 Long-term risks

  • Tachycardia and unknown long-term cardiac effects of chronic GcgR agonism
  • Thyroid C-cell tumors (class effect — rodent data)
  • Rapid weight loss-associated bone density changes
  • Unknown long-term glucagon receptor desensitization
  • Insufficient safety data beyond 48 weeks

6.5 Research best practices

  • Store lyophilized at −20 °C; protect from light
  • Monitor resting heart rate and blood pressure in protocols
  • Initiate at low dose (1–2 mg) with 4-week escalation intervals
  • Assess liver enzymes and gallbladder function periodically in long-term protocols
Safety data disclaimer. Safety assessments are based on published literature and are for educational reference only. Clinical evidence varies significantly between peptides. Always consult primary research and current regulatory guidance.

7 Frequently asked questions

What is the primary use case for Retatrutide in research?
Retatrutide is being researched for severe obesity, treatment-resistant metabolic syndrome, and non-alcoholic fatty liver disease (NAFLD). Its triple-hormone action provides the most aggressive metabolic reset of any compound currently in trials.
How does it burn fat without exercise?
The addition of the glucagon receptor agonism actively increases the body's resting energy expenditure. This means it induces a state of thermogenesis and actively mobilizes stored liver and body fat for energy, independent of physical activity.
How fast does it work compared to others?
In Phase 2 trials, participants hit an average of 24.2% body weight loss in just 48 weeks. It reaches milestones much faster than dual or single agonists, with many subjects achieving normal liver fat levels rapidly.

8 References

  1. Retatrutide effects on diabetic rats' cognition PubMed (2026). Ferreira J, et al.. View source
  2. Retatrutide and the urinary tract infection signal: Is the answer hidden in timing? PubMed (2026). Koufakis T, et al.. View source
  3. Retatrutide fact check: Has a man died after taking the unapproved weight loss jab? PubMed (2026). Mahase E, et al.. View source
  4. Effects of retatrutide on learning and memory in streptozotocin-induced male diabetic rats PubMed (2026). Keskin U, et al.. View source

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9 See also

For research reference only. Not medical advice. Peptides may be regulated or restricted in your jurisdiction. Entry validated by the PeptidePlaza Biomedical Research Desk; see editorial standards.

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