Retatrutide
Retatrutide is an investigational once-weekly triple hormone receptor agonist designed to activate the GIP, GLP-1, and glucagon receptors. In mid-stage obesity trials, it produced substantial weight loss and metabolic improvements, but it remains under clinical investigation and is not yet an approved medicine.
Overview
Retatrutide, also known as LY3437943, is a synthetic peptide being developed by Eli Lilly for obesity, type 2 diabetes, and other cardiometabolic conditions. Lilly and published studies describe it as a single molecule that combines incretin and glucagon-pathway activity in one agent.
What it is
Retatrutide is an investigational peptide-based triple agonist. It is not a supplement and not a marketed peptide product. Lilly states it is legally available only to participants in Lilly-sponsored clinical trials.
Mechanism (high level)
Retatrutide activates the GIP receptor, GLP-1 receptor, and glucagon receptor. Lilly says these pathways may reduce food intake, improve glucose homeostasis, increase insulin secretion, support lipid metabolism, and help maintain energy expenditure during weight loss. Lilly also states the molecule includes a C20 fatty diacid moiety that promotes albumin binding and extends half-life to support once-weekly dosing.
Quick facts
- Dosage
- There is no approved standard dose yet. In the Phase 2 obesity trial, retatrutide was studied as 1 mg, 4 mg, 8 mg, and 12 mg once weekly, with dose escalation used to improve tolerability.
- Route
- Subcutaneous injection, once weekly in clinical trials.
- Cycle
- No approved cycle has been established. In obesity research, participants were treated for 48 weeks, and in the first Phase 3 type 2 diabetes trial the reported treatment period was 40 weeks.
- Storage
- Follow clinical-trial or manufacturer instructions exactly Protect from heat and light Do not use beyond labeled storage limits Because retatrutide is not commercially approved, storage guidance should come from the official study or dispensing source only
Research indications
- Obesity research
- Overweight with weight-related conditions research
- Type 2 diabetes research
- Knee osteoarthritis with obesity research
- Obstructive sleep apnea research
- Cardiovascular outcomes research
- Renal outcomes research
- Metabolic dysfunction-associated steatotic liver disease research
- Chronic low back pain in obesity research
Research protocols (education)
obesity trial and Lilly’s Phase 3 updates.
Once-weekly subcutaneous dosing Phase 2 obesity study with 1 mg, 4 mg, 8 mg, and 12 mg arms 48-week obesity protocol in adults without diabetes 40-week Phase 3 type 2 diabetes trial Dose escalation used to improve gastrointestinal tolerability
Interactions
Often avoided with
- Unsupervised use of products claiming to be retatrutide
- Use outside legitimate clinical-trial or future approved medical channels
- Pregnancy unless specifically clinician supervised
- Breastfeeding unless specifically clinician supervised
- Use with caution in people sensitive to GLP-1–type gastrointestinal effects
- Use with caution in people who cannot tolerate appetite-suppressing incretin therapies
Often combined with
- Clinical-trial participation with medical supervision
- Use only under formal prescribing approval if approved in the future
- Metabolic and obesity research settings
- Careful clinician monitoring for tolerability and metabolic response
Peptides discussed online are not substitutes for diagnosis or prescriptions.
Side effects & safety
- Nausea
- Vomiting
- Diarrhea
- Constipation
- Gastrointestinal adverse events most common during dose escalation
- Possible increase in heart rate
- Investigational safety profile only
- Long-term approved-use safety not yet established
Regulatory notes
- Not FDA approved
- Investigational use only
- Not available for public use
- Legally available only in Lilly-sponsored clinical trials at present
- Phase 3 trials are ongoing in obesity, type 2 diabetes, and related conditions
FAQ
What is retatrutide?
Retatrutide is an investigational once-weekly peptide medicine that activates the GIP, GLP-1, and glucagon receptors.
Is retatrutide FDA approved?
No. Retatrutide is still investigational and has not been approved for public use.
What is retatrutide used for?
It is being studied for obesity, type 2 diabetes, and several related cardiometabolic and obesity-associated conditions
How much weight loss has retatrutide shown?
In Phase 2 obesity data, mean weight reduction reached up to 17.5% at 24 weeks and 24.2% at 48 weeks at the highest studied dose.
Is retatrutide available now?
For research purposes, only. Lilly says it is not yet available for public use and should not be obtained outside legitimate clinical trials.
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Educational content only. This material is not medical advice. Verify legality, sourcing, and dosing with a qualified professional.