What is Retatrutide?
Retatrutide (LY3437943) is a novel triple-receptor agonist that targets three incretin-related receptors simultaneously:
- GLP-1 (glucagon-like peptide-1) receptor
- GIP (glucose-dependent insulinotropic polypeptide) receptor
- Glucagon receptor
This triple mechanism represents the newest evolution in incretin-based research, building on the success of single (semaglutide) and dual (tirzepatide) receptor agonists. The addition of glucagon receptor activity may provide unique metabolic effects.
The 50mg vial is the largest presentation on the research market. Reconstituted with 5mL of bacteriostatic water it holds a 10mg/mL concentration, keeping injection volumes small — every dose up to 8mg fits inside a single U-100 syringe — while providing the most doses per vial of any size.
Quick Reference
| Parameter | Value |
|---|---|
| Peptide Amount | 50mg |
| Recommended BAC Water | 5mL |
| Resulting Concentration | 10mg/mL (10000mcg/mL) |
| Typical Research Dose | 1mg - 12mg weekly |
| Frequency | Once weekly |
| Research Duration | 24-48 weeks |
Reconstitution Guide
Materials Needed
- Retatrutide 50mg lyophilized vial
- Bacteriostatic water (BAC water)
- Insulin syringes (U-100, 29-31 gauge)
- Alcohol swabs
- Sharps container
Step-by-Step Instructions
-
Prepare workspace — Clean environment, gather materials, thorough handwashing.
-
Clean vial stoppers — Wipe both vials with alcohol swabs. Allow complete drying.
-
Draw BAC water — Draw 5mL bacteriostatic water using sterile syringe.
-
Add to peptide — Inject slowly along inside wall of vial. Never spray directly onto powder.
-
Dissolve — Allow 5-10 minutes for complete dissolution. Gentle swirl only — no shaking.
-
Verify — Solution must be completely clear and colorless.
-
Label and store — Note reconstitution date. Refrigerate immediately.
Dosage Protocol
Concentration Calculations
With 50mg peptide in 5mL BAC water:
- Concentration: 10mg/mL = 10000mcg/mL
- Per unit (U-100 syringe): 100mcg per unit
Common Dose Calculations
| Desired Dose | Draw Volume | Syringe Units |
|---|---|---|
| 1mg | 0.10mL | 10 units |
| 2mg | 0.20mL | 20 units |
| 4mg | 0.40mL | 40 units |
| 8mg | 0.80mL | 80 units |
| 12mg | 1.20mL | Split into 2 injections |
Suggested Titration Protocol
Based on phase 2 clinical trial design:
| Week | Dose | Notes |
|---|---|---|
| 1-4 | 1mg | Initial assessment |
| 5-8 | 2mg | First escalation |
| 9-12 | 4mg | Second escalation |
| 13-20 | 8mg | Third escalation |
| 21+ | 12mg | Maximum studied dose |
Important Notes:
- Each dose level maintained minimum 4 weeks
- Escalation based on tolerance
- Not all protocols require maximum dose
- Lower doses (4-8mg) may be sufficient for many research objectives
Injection Guide
Subcutaneous Administration
- Clean injection site with alcohol swab
- Pinch skin fold at chosen site
- Insert needle at 90° angle
- Inject slowly (large volumes over 10-15 seconds)
- Wait 10 seconds before withdrawing
- Do not massage site
Site Selection
Preferred sites:
- Abdomen (most common) — avoid 2 inches around navel
- Outer thigh
- Upper arm
Large Volume Injections
For doses at or above 12mg (>1mL):
- Consider splitting into 2 separate injections
- Use different sites for each injection
- Complete both injections within 15-minute window
Storage Requirements
Lyophilized (Powder)
- Temperature: -20°C (-4°F) or colder
- Duration: 2+ years
- Conditions: Dry, dark, protected from moisture
Reconstituted
- Temperature: 2-8°C (36-46°F)
- Duration: 4-6 weeks
- Conditions: Refrigerated, protected from light, never freeze
Research Considerations
Triple-Receptor Mechanism
Retatrutide’s unique mechanism targets:
GLP-1 Receptor:
- Appetite suppression
- Insulin secretion (glucose-dependent)
- Delayed gastric emptying
- Established metabolic effects
GIP Receptor:
- Enhanced insulin response
- Potential adipose tissue effects
- Complements GLP-1 activity
Glucagon Receptor:
- Increased energy expenditure
- Hepatic glucose output regulation
- Potential thermogenic effects
- May enhance weight reduction beyond dual agonists
Comparison to Other Incretins
| Peptide | GLP-1 | GIP | Glucagon | Max Weight Effect* |
|---|---|---|---|---|
| Semaglutide | ✓ | − | − | ~15-17% |
| Tirzepatide | ✓ | ✓ | − | ~20-22% |
| Retatrutide | ✓ | ✓ | ✓ | ~24% |
*Based on clinical trial data at maximum doses
Phase 2 Trial Highlights
Key findings from initial trials:
- Dose-dependent effects on body weight
- Effects observed across all dose groups
- Generally manageable tolerability profile
- Novel metabolic parameter changes
Safety Considerations
Research Precautions
- Retatrutide is an investigational compound
- Phase 3 trials ongoing
- Not approved for any indication in any jurisdiction
- Research use only — not for human consumption
- Limited long-term safety data available
Handling
- Use sterile technique for all preparations
- Never reuse needles or syringes
- Proper sharps disposal
- Store securely away from unauthorized access
Sourcing for Research
Source from verified suppliers that provide third-party testing and certificates of analysis (COA) for each batch. Compare purity documentation, shipping conditions, and batch traceability before purchasing research materials.
Scientific References
- Jastreboff AM, et al. “Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial.” N Engl J Med. 2023;389:514-526.
- Rosenstock J, et al. “Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial.” Lancet. 2023;402:529-544.
- Finan B, et al. “A rationally designed monomeric peptide triagonist corrects obesity and diabetes in rodents.” Nat Med. 2015;21:27-36.
Last updated: July 19, 2026
Disclaimer: This information is for educational and research purposes only. Retatrutide is an investigational compound in clinical development and is not approved for any use. Research-grade peptides are not intended for human consumption. Always follow applicable laws and institutional guidelines.