Retatrutide

LY3437943 · Triple agonist

An investigational triple GIP/GLP-1/glucagon receptor agonist still in clinical trials. Not approved anywhere.

Research use only. This compound is sold for laboratory research and is not approved by the FDA for human use. Everything below is reference information about what circulating protocols state — not a recommendation to use it.

At a glance

Category: Metabolic
Half-life: ~6 days
Typical vial sizes: 5 mg · 10 mg · 20 mg
Commonly cited dose: 1000–12000 mcg
Frequency: once weekly
Routes: Subcutaneous

A 5 mg vial, worked through.

Reconstituting a 5 mg vial of Retatrutide with 2 mL of bacteriostatic water gives 2.5 mg/mL. A 1000 mcg dose is then:

40units(0.4 mL) — about 5 doses per vial

Storage

Lyophilised (unmixed): Refrigerated, protected from light.
Reconstituted: Refrigerate at 2–8°C.

What people log it against

Outcomes users commonly track alongside this compound. Listing them is not a claim that it produces them.

Weight management (investigational)

Read alongside Retatrutide

Compounds this one is commonly compared with, combined with, or mistaken for. Listing a pairing is not a suggestion to run them together.

TirzepatideFDA approvedSuccessive generations of the same idea — dual-receptor versus triple-receptor agonism. Their approval status is not the same.

References

Each source below establishes only the specific claim noted with it, last checked 2026-08-13. Dose ranges, frequencies and storage times reflect what circulating protocols commonly state and are not established by these references.

Urva et al., Lancet 2022 (LY3437943 phase 1b) — PMID 36354040
Mean terminal half-life approximately 5-7 days across dose levels, Tmax 1-3 days, supporting once-weekly dosing. Confirms halfLifeHours 144 (6 days).

Run your own numbers

Pick Retatrutide from the preset list to start from a typical vial.

Your vial

Peptide in vial

As printed on the vial label

Bacteriostatic water added

How much you inject into the vial

Dose you want

mcg

1000 mcg = 1 mg

Syringe size

Start from a peptide

Fills in a common vial size and the low end of commonly cited protocols. Always check against your own vial.

Draw this much

5units

on a 1 mL U-100 insulin syringe

Concentration: 5 mg/mL
Volume: 0.05 mL
Doses in this vial: 40

Keep this vial. VialPal holds the concentration, counts down the doses left in it, and logs the ones you actually took.

VialPal does the arithmetic — it does not tell you what to take. Dose decisions belong between you and a qualified clinician.