The R3TA exists in two forms: freeze-dried vial and the pre-filled pen, often called “R3 pen” or “reta pen”. The peptide is the same; what changes is its presentation, its conservation and its price.
The freeze-dried vial
The vial contains R3TA in the form of freeze-dried powder : the water was removed under vacuum, making the peptide very stable. Before use in the laboratory, the powder is redissolved with bacteriostatic water.
- Advantages : high stability, six dosages available, best price per milligram.
- Constraint : a reconstitution stage.
The pre-filled pen (R3 pen)
The pen contains R3TA already in solution. No powder or solvent to handle.
- Advantages : ready to use, compact format.
- Constraints : storage in the refrigerator (2 to 8°C), without freezing; higher price per milligram.
Comparison of prices per milligram
| Format | Price | Price per mg |
|---|---|---|
| Lyophilized vial 10 mg | 49,99 € | 5,00 € |
| Lyophilized vial 20 mg | 94,99 € | 4,75 € |
| Lyophilized vial 30 mg | 139,99 € | 4,67 € |
| Lyophilized vial 40 mg | 179,99 € | 4,50 € |
| Lyophilized vial 50 mg | 219,99 € | 4,40 € |
| Lyophilized vial 60 mg | 259,99 € | 4,33 € |
| 10 mg pre-filled pen | 89,99 € | 9,00 € |
| Pack of 3 pens (3 × 10 mg) | 199,99 € | 6,67 € |
Prices including tax indicated on the date this page was updated; the reference price is that displayed on each product sheet.
Storage
- Vial : in the refrigerator, away from light; in the freezer for a long time.
- Pen : in the refrigerator only, never in the freezer.
All the details in our guide store freeze-dried peptides.
In summary
- You favor the price per milligram : choose a large freeze-dried vial.
- You favor the simplicity : choose the pen, or the pack of 3 pens to reduce the unit price.
Fact sheet
- Molecule
- Retatrutide (LY3437943), nicknamed R3
- Receptor or target
- GLP-1, GIP and glucagon
- Published half-life
- About 6 days
- Vial
- Freeze-dried powder, to be reconstituted before use
- Pen
- Ready-made solution, to be stored between 2 and 8 °C
- Regulatory status
- In phase 3 trials, with no marketing authorisation
What the research says
Summary of published data, written by the PeptidLab team. It describes molecules studied in the laboratory or in clinical trials: nothing here is an indication for use.
2022PreclinicalCell Metab
Description of retatrutide: a single peptide that activates three receptors, with a half-life compatible with one injection a week.
2023Phase 2N Engl J Med
In 338 adults with obesity or overweight, up to 24.2% weight loss at 48 weeks with the highest dose.
2023Phase 2The Lancet
In patients with type 2 diabetes, greater reductions in HbA1c and weight than with placebo and dulaglutide at high doses.
Safety: what studies report
- In phase 2 trials, the most common adverse effects were digestive and dose-dependent; a rise in heart rate was also observed.
Sources
Links to PubMed or to the original document. Articles in English.
- Coskun T et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: from discovery to clinical proof of concept. Cell Metab, 2022. PubMed
- Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med, 2023. PubMed
- Rosenstock J et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA. The Lancet, 2023. PubMed
Updated October 2026.
Frequently asked questions
What is the difference between R3TA in a vial and in a pen?
The vial contains the lyophilized powder peptide, to be reconstituted with bacteriostatic water. The pen contains the peptide already in solution, ready to use.
What is the “R3 pen”?
“R3 pen” and “reta pen” are the common names for R3TA in a pre-filled pen.
Which format of R3TA is the cheapest?
Per milligram, large freeze-dried vials are the most economical. The pack of 3 pens reduces the price of each pen compared to purchasing individually.
This guide has an informative and scientific purpose. PeptidLab products are intended exclusively for laboratory research and are not intended for human or animal consumption.
