Investigational triple agonist
Reconstitute retatrutide, an investigational triple GIP/GLP-1/glucagon agonist that is not FDA-approved, and get the exact units to draw. Enter your vial strength, bacteriostatic water volume, and weekly dose for the precise mark on a U-100 insulin syringe.
Draw to
Draw to the 10 unit mark. That is 0.100 mL of solution.
Informational and educational only. Not medical advice. This tool performs math on values you enter and is not a substitute for your prescriber.
Units to draw are calculated from your current vial and water settings above and update live.
| Period | Dose | Draw (units) | Volume |
|---|---|---|---|
| Weeks 1-4current | 2 mg | 10 | 0.100 mL |
| Weeks 5-8 | 4 mg | 20 | 0.200 mL |
| Weeks 9-12 | 8 mg | 40 | 0.400 mL |
| Week 13+ | 12 mg | 60 | 0.600 mL |
Retatrutide (LY3437943) is an investigational triple GIP, GLP-1, and glucagon receptor agonist developed by Eli Lilly. It has not received FDA approval as of June 2026 and is currently in Phase 3 trials (TRIUMPH programme). Its elimination half-life is approximately 6 days (144 hours), enabling once-weekly subcutaneous dosing. Steady state is reached over roughly 4 to 5 weeks of weekly dosing.
Add your chosen volume of bacteriostatic water to the lyophilized vial, directing the stream gently against the glass wall, and swirl slowly (do not shake) until fully dissolved. The calculator above converts your vial strength and water volume into the exact units to draw for your target dose.
In the NEJM Phase 2 obesity trial (Jastreboff et al., 2023), participants in the 12 mg arm started at 2 mg once weekly and escalated every 4 weeks: 2 mg (weeks 1-4), 4 mg (weeks 5-8), 8 mg (weeks 9-12), then 12 mg from week 13 onward. Retatrutide is investigational and there is no approved prescribing schedule; any use is under clinical trial or investigational protocols only.
It depends on your reconstitution concentration. With a 10 mg vial in 1 mL of bacteriostatic water (10 mg/mL), a 2 mg dose is 0.20 mL, which equals 20 units on a U-100 insulin syringe. Enter your vial size and water volume in the calculator above for your exact number.
No. As of mid-2026, retatrutide (LY3437943) remains an investigational drug developed by Eli Lilly. It is not approved by the FDA for any indication. Phase 3 trials are ongoing under the TRIUMPH programme. This calculator is for educational purposes only and does not constitute medical advice.
Source: Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. · How we calculate