Comparisons 7 min 2024-06-10
Tirzepatide vs. Retatrutide: Is the Triple Agonist Even Better?
Retatrutide, a triple hormone receptor agonist, has shown up to 24% weight loss in trials. How does it compare to tirzepatide's dual action?
As tirzepatide established the dual agonist category, the next frontier has arrived: triple agonism. Retatrutide, also developed by Eli Lilly, targets three receptors.
The Triple Agonist Concept
| Feature | Tirzepatide | Retatrutide |
|---|---|---|
| Receptors | GIP + GLP-1 | GIP + GLP-1 + Glucagon |
| Max Dose Tested | 15 mg | 12 mg |
| Peak Weight Loss | ~22.5% | ~24.2% |
| Phase | Approved (Phase 3) | Phase 2 (Phase 3 ongoing) |
| Developer | Eli Lilly | Eli Lilly |
Why Add Glucagon?
Glucagon receptor activation provides additional mechanisms:
- Increased energy expenditure — glucagon raises metabolic rate
- Enhanced fat oxidation — promotes fat burning
- Reduced liver fat — glucagon directly reduces hepatic steatosis
- Appetite suppression — additional central effects
The concern with glucagon was that it raises blood sugar, but this is offset by the GLP-1 and GIP components.
Phase 2 Trial Results
In the Phase 2 trial (published in NEJM, 2023):
- Retatrutide 12 mg: -24.2% body weight at 48 weeks
- Dose-dependent weight loss across all groups
- Favorable safety profile similar to tirzepatide
- Weight loss curve had not plateaued at 48 weeks
Comparison Points
Advantages of Retatrutide (Potential)
- Slightly greater weight loss
- Additional metabolic benefits from glucagon activation
- May be more effective for liver fat reduction
- Weight loss appears to continue beyond 48 weeks
Advantages of Tirzepatide
- FDA-approved and available now
- Extensive Phase 3 safety data
- Long-term data available
- Well-established dosing protocols
- Known insurance coverage pathways
Current Status and Timeline
- Phase 3 trials (TRIUMPH program) are underway
- Results expected 2025-2026
- FDA approval could come as early as 2026-2027
- Will be marketed under a different brand name
What This Means for Patients
- Tirzepatide remains the best available option today
- Retatrutide may offer additional benefits in the future
- The field is moving toward more effective, multi-target therapies
- Patients currently on tirzepatide should continue their treatment
- The pipeline suggests even better options are coming
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before making any medical decisions.