Retatrutide Dosage Guide: Reported Study Ranges, Reconstitution & Unit Charts (2026)
Retatrutide (GLP-3) escalation ranges reported in Phase 2 literature, plus reconstitution math, mg-to-insulin-unit charts, and storage guidance.
By PX1 Research Team · August 4, 2026
Retatrutide (GLP-3) in the published literature
Retatrutide is a triple agonist — GIP, GLP-1 and glucagon receptor — investigated in Phase 2 obesity and metabolic trials. Because it hits three receptors, the reported study designs escalate slowly, and the escalation schedule is the single most discussed variable in the literature.
Reported study escalation ranges
Published Phase 2 protocols used weekly subcutaneous administration with monthly step-ups. Commonly reported arms:
| Study phase | Reported weekly amount | Typical duration |
|---|---|---|
| Initiation | 1 mg | 4 weeks |
| Step 1 | 2 mg | 4 weeks |
| Step 2 | 4 mg | 4 weeks |
| Step 3 | 8 mg | 4 weeks |
| Maximal arms | 12 mg | remainder of study |
Higher arms in trials reported larger effect sizes alongside a higher rate of gastrointestinal adverse events, which is why escalation intervals in the literature are long rather than compressed.
Reconstitution math for a 10 mg vial
A 10 mg lyophilized vial reconstituted with 2 mL of bacteriostatic water yields 5 mg/mL. On a standard U-100 insulin syringe (100 units = 1 mL):
| Target amount | Volume at 5 mg/mL | Insulin units |
|---|---|---|
| 1 mg | 0.20 mL | 20 |
| 2 mg | 0.40 mL | 40 |
| 4 mg | 0.80 mL | 80 |
| 5 mg | 1.00 mL | 100 |
Reconstituting the same vial with 1 mL gives 10 mg/mL and halves every unit figure. Run your own numbers with the peptide calculator.
Handling and stability
Lyophilized retatrutide is stable at room temperature in a sealed vial and should be refrigerated at 2–8 °C after reconstitution, with bacteriostatic water (0.9% benzyl alcohol) giving roughly a 28-day in-use window. Add diluent down the vial wall rather than directly onto the cake, and swirl instead of shaking.
Documentation to check before use
Confirm the lot COA shows HPLC purity, LC-MS identity, and endotoxin results. PX1 publishes both at /purity-reports and /endotoxin-reports. Product page: GLP-3 (Retatrutide).
All figures below are reported from published laboratory literature and are provided for informational and laboratory-research context only. PX1 Research supplies compounds for laboratory and research use only — not for human or veterinary use.