Retatrutide (LY3437943) is a first-in-class triple GIP/GLP-1/glucagon receptor agonist currently under Phase 3 clinical development. In Phase 2 trials, participants achieved up to 24.2% body weight reduction over 48 weeks — surpassing every existing weight-loss compound in head-to-head comparisons.
What Makes Retatrutide Different?
Unlike tirzepatide (dual GIP/GLP-1) or semaglutide (GLP-1 only), retatrutide adds a third mechanism: glucagon receptor agonism. This drives additional thermogenic activity and hepatic fat clearance on top of the appetite suppression seen with other GLP-1 agents.
| Compound | Receptors | Max Weight Loss (Phase 2) |
|---|---|---|
| Semaglutide | GLP-1 | ~15% |
| Tirzepatide | GLP-1 + GIP | ~22% |
| Retatrutide | GLP-1 + GIP + Glucagon | ~24.2% |
Retatrutide Dosage Protocol: Research Escalation Schedule
Based on the LY3437943 Phase 2 trial design, the following escalation schedule was used in the 12mg maintenance arm:
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Try the Calculator →| Week | Dose (subcutaneous, once weekly) | Purpose |
|---|---|---|
| 1–4 | 2 mg | Tolerance establishment |
| 5–8 | 4 mg | Initial titration |
| 9–12 | 6 mg | Mid-range escalation |
| 13–16 | 8 mg | Upper titration |
| 17–20 | 10 mg | Near-maintenance |
| 21+ | 12 mg | Maintenance dose |
Retatrutide vs Tirzepatide
For pure metabolic and weight outcomes, retatrutide’s triple agonism makes it more potent. Tirzepatide has more Phase 3 cardiovascular data. Many researchers combine retatrutide with BPC-157 to offset potential catabolic signaling from glucagon receptor activity.
Sourcing Quality Standards
Peptide quality varies across vendors. For retatrutide, critical quality markers are HPLC purity ≥98%, mass spectrometry verification of the correct molecular weight (4,731 Da), endotoxin testing, and an independent third-party COA.
Prax Peptides provides full third-party HPLC and mass spec COAs on every retatrutide batch. View current retatrutide availability →
Side Effects
The most common side effects in Phase 2 were nausea, vomiting, and decreased appetite — all dose-dependent and typical of the GLP-1 class. Slow dose escalation (starting at 2 mg) is the most effective mitigation strategy.
Prax Peptides supplies research-grade compounds with 99%+ purity, verified by independent third-party analysis.
⚠️ Research Use Only: All compounds referenced on this site are intended strictly for laboratory research purposes. They are not approved for human use or consumption by the FDA or any regulatory authority. This content is for informational purposes only and does not constitute medical advice.