Exenatide vs Retatrutide
A neutral, side-by-side comparison of two glp-1 & metabolic peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
Exenatide
First GLP-1 receptor agonist approved for clinical use (2005), derived from the Gila monster venom peptide exendin-4. Available as twice-daily immediate-release (Byetta) and once-weekly extended-release (Bydureon BCise) formulations. Established the GLP-1 agonist drug class and provided the foundational clinical evidence for cardiovascular and metabolic benefits.
Full profileRetatrutide
Retatrutide (LY3437943) is Eli Lilly's investigational once-weekly triple agonist of the GIP, GLP-1, and glucagon receptors. Phase 2 data showed 24.2% mean weight loss at 48 weeks; the Phase 3 TRIUMPH program has since reported topline weight loss approaching 28–30% — among the largest reductions recorded for any obesity pharmacotherapy. It is not yet FDA-approved.
Full profile| Exenatide | Retatrutide | |
|---|---|---|
| Category | GLP-1 & Metabolic | GLP-1 & Metabolic |
| Also known as | Byetta, Bydureon, AC2993, exendin-4 | LY3437943, Triple G, GIP/GLP-1/Glucagon Receptor Agonist |
| Evidence | FDA-approved | Investigational (in trials) |
| Dosing range | 5mcg–2mg (weekly ER) mcg, Twice daily (immediate-release) or once weekly (extended-release) | 2mg–12mg mg, once weekly |
| Administration | Subcutaneous injection | Subcutaneous injection (weekly) |
| Key side effects | Nausea (most common, especially initial weeks), Vomiting, Diarrhea, Injection site nodules (extended-release formulation) | Nausea (most common, dose-dependent), Vomiting, Diarrhea, Constipation |
| Cited sources | 2 references | 6 references |
Key differences
- Evidence level differs: Exenatide is fda-approved, while Retatrutide is investigational (in trials).
- Administration: Exenatide — Subcutaneous injection; Retatrutide — Subcutaneous injection (weekly).
- Dosing units differ: Exenatide is dosed in mcg, Retatrutide in mg — they operate at different scales.
- Frequency: Exenatide is typically Twice daily (immediate-release) or once weekly (extended-release); Retatrutide is once weekly.
- Research depth: this profile cites 2 sources for Exenatide vs 6 for Retatrutide.
How each works
Exenatide
Exenatide was identified from Gila monster (Heloderma suspectum) venom as exendin-4, a peptide with ~53% homology to human GLP-1 but with DPP-4 resistance enabling longer activity. Clinical trials demonstrated HbA1c reductions of 0.8–1.0%, weight loss of 2–4kg, and cardiovascular safety (EXSCEL trial showed non-inferiority). The extended-release microsphere formulation achieved comparable efficacy with once-weekly dosing.
Retatrutide
Across the Phase 2 trial (NEJM 2023, Jastreboff et al.) and the Phase 3 TRIUMPH registrational program (TRIUMPH-1 through -4), retatrutide has produced dose-dependent weight loss reaching ~28.3% at 80 weeks (TRIUMPH-1, 12 mg) and ~28.7% at 68 weeks in a knee-osteoarthritis population (TRIUMPH-4, 12 mg), alongside improvements in glycemia, blood pressure, lipids, and liver fat. The glucagon component is thought to add energy expenditure on top of the appetite suppression driven by GLP-1 and GIP. As of mid-2026, Phase 3 efficacy figures are topline (press-release/conference level) and not yet published in full peer-reviewed form.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.