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. Being listed here does not mean it is approved, recommended, or evaluated for safety or efficacy.

Part of the GLP-1 medicines reference: how this compares with the other GLP-1 drugs, and what the FDA says about compounded versions.

At a glance

Category: Metabolic
Half-life: ~6 days
Typical vial sizes: 5 mg · 10 mg · 20 mg

Concentration by water volume

Pure arithmetic: the vial strength divided by the water added. The dose itself comes from your clinician, pharmacy, product instructions, or research protocol — enter it in the calculator below.

Vial	Water added	Concentration	Per U-100 unit
5 mg	1 mL	5 mg/mL	50 mcg
5 mg	2 mL	2.5 mg/mL	25 mcg
5 mg	3 mL	1.667 mg/mL	16.667 mcg
10 mg	1 mL	10 mg/mL	100 mcg
10 mg	2 mL	5 mg/mL	50 mcg
10 mg	3 mL	3.333 mg/mL	33.333 mcg
20 mg	1 mL	20 mg/mL	200 mcg
20 mg	2 mL	10 mg/mL	100 mcg
20 mg	3 mL	6.667 mg/mL	66.667 mcg

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 or mistaken for. Listing a pairing is not a suggestion to use them together.

TirzepatideFDA-approved product existsSuccessive 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. Storage times reflect common handling guidance 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. Confirms the 144-hour half-life used here (6 days).

Run your own numbers

Enter the dose and concentration from your clinician, pharmacy, product instructions, or research protocol. VialPal handles the math.

Your vial

Peptide in vial

As printed on the vial label

Bacteriostatic water added

How much water you add to the vial

Dose from your instructions

mcg

From your clinician, pharmacy, product instructions, or research protocol. 1000 mcg = 1 mg

Syringe size

Fill in a vial size

Fills in a vial size this compound is commonly sold in. It does not fill in a dose — check the size against your own vial label.

Draw this much

Enter your numbers

Still needed: vial strength, bacteriostatic water, dose. Use the figures on your vial label and the dose from your clinician, pharmacy, product instructions, or research protocol — VialPal handles the math.

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

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