Retatrutide (GLP-3): Complete Research Guide (Specs, Reconstitution, Storage)
Retatrutide (GLP-3) — GIP/GLP-1/glucagon triple receptor agonist. Specifications, reported study ranges, reconstitution math, storage rules and lot documentation.
By PX1 Research Team · August 4, 2026
What Retatrutide (GLP-3) is
Retatrutide (GLP-3) is a GIP/GLP-1/glucagon triple receptor agonist. PX1 supplies it as a lyophilized research-grade material for metabolic and body-composition research, tested to ≥99% HPLC purity with LC-MS identity confirmation on every lot.
| Property | Detail |
|---|---|
| Compound | Retatrutide (GLP-3) (LY3437943) |
| Class | GIP/GLP-1/glucagon triple receptor agonist |
| Molecular weight | 4731 g/mol |
| Reported half-life | ~6 days |
| Vial sizes | 10 mg / 15 mg / 20 mg / 30 mg |
| Purity | ≥99% HPLC · LC-MS identity · COA per lot |
| Form | Lyophilized powder |
Reported study parameters
Published laboratory literature describes the following ranges. These are reported observations from research settings — not recommendations.
| Study arm | Reported amount | Cadence |
|---|---|---|
| Initiation | 1 mg | weekly × 4 |
| Step 1 | 2 mg | weekly × 4 |
| Step 2 | 4 mg | weekly × 4 |
| Step 3 | 8 mg | weekly × 4 |
| Maximal arms | 12 mg | weekly |
Reconstitution
A typical preparation is 10 mg + 2 mL bacteriostatic water = 5 mg/mL. Add bacteriostatic water slowly down the inside wall of the vial, never directly onto the lyophilized cake, and swirl rather than shake — shear and foaming at the air-liquid interface degrade peptide structure. Run exact insulin-unit numbers for your own concentration in the peptide calculator.
Storage and stability
Sealed lyophilized Retatrutide (GLP-3) is stable at room temperature for shipping and for 18–24 months when kept cool, dry and out of light; −20 °C is preferred for long-term storage. Once reconstituted with bacteriostatic water (0.9% benzyl alcohol), hold at 2–8 °C and observe the standard 28-day in-use window. Aliquot before freezing to avoid repeated freeze-thaw cycles, which drive aggregation and measurable purity loss.
How to verify what you received
Ask for the COA for your specific lot — not a generic PDF. A real COA carries the lot number, manufacture and retest dates, an HPLC chromatogram (not just a percentage), the LC-MS spectrum matching expected mass, and endotoxin plus sterility results. See how to read a COA.
Commonly researched alongside
- Cagrilintide — amylin-pathway and satiety-signalling research
- Tesamorelin — GHRH-axis and visceral-adipose research
Frequently asked questions
What purity is PX1 Retatrutide (GLP-3)? ≥99% by HPLC, with LC-MS identity confirmation and endotoxin testing documented per lot.
What vial sizes are available? 10 mg / 15 mg / 20 mg / 30 mg.
How is it shipped? Lyophilized material is shelf-stable and ships at ambient temperature from U.S. facilities, same-day on business-day orders placed before cutoff. See shipping.
Is it made in the USA? Yes — synthesized, purified, lyophilized and vialed domestically. See /manufacturing-process.
How PX1 documents every lot
Every PX1 lot ships with HPLC purity, LC-MS identity, residual solvent, moisture (Karl Fischer), sterility and endotoxin data. Lot documentation is published at /purity-reports, /endotoxin-reports and /coa. Synthesis, purification, lyophilization and vial fill happen in U.S. facilities — see /manufacturing-process.
Product page: Retatrutide (GLP-3) · Full catalog: /all-peptides
Research use only. PX1 Research supplies compounds for laboratory and in-vitro research. Nothing here is medical advice, a dosing recommendation, or an offer for human or veterinary use. Figures cited are reported from published laboratory literature.