Retatrutide
Mechanism
This is the one that went for three: GLP-1, GIP, and glucagon receptor, all three pathways firing at once. That glucagon piece is the flex tirzepatide doesn't have, burning liver fat and torching extra energy on top of everything the dual drugs already do.
Key Benefit
TRIUMPH-4 Phase 3: 28.7% body weight loss at 68 weeks. The highest ever reported in an obesity trial. Phase 2 showed 24.2% at 48 weeks.
Evidence Base
The TRIUMPH program is already stacking Phase 3 trials. TRIUMPH-4 published in December 2025. TRANSCEND-T2D-1 lands March 2026. The NDA is expected late 2026, with FDA approval potentially landing 2027 to 2028: real dates, not vague promises.
Route & Rationale
Subcutaneous injection (weekly). Peptide requires parenteral delivery. Once-weekly dosing maintains sustained triple-receptor activation.
Interactions
Same GLP-1 class interaction profile. Unique side effect: dysesthesia (skin sensitivity/tingling) reported in ~20.9% at highest dose. Discuss with physician.
Regulatory Status
Investigational. Still Phase 3, which means it is not sitting on a pharmacy shelf and will not be for a while. Anything sold outside a clinical trial is a gray-market research chemical: unverified, unregulated, and not the same thing as the drug in the TRIUMPH trials.
Hard Contraindications
MTC/MEN2 thyroid cancer, Pregnancy/planning
Cautions
Pancreatitis, Diabetes
For information and research purposes only. This is not medical advice and not a recommendation to use this substance. Discuss anything here with your healthcare provider.
