Research compound comparison
Retatrutide vs Tirzepatide
Both compounds are long-acting acylated peptides built on the same design principle, and they are frequently studied side by side. The difference that matters is receptor coverage: tirzepatide engages two pathways, retatrutide engages three. This page compares them on structure, pharmacokinetics, trial status and laboratory handling. Both are supplied for in vitro research only and neither is for human or veterinary use.
Side-by-side comparison
| Attribute | Retatrutide | Tirzepatide |
|---|---|---|
| Research code | LY3437943 | LY3298176 |
| Receptor targets | GIP + GLP-1 + glucagon (triple) | GIP + GLP-1 (dual) |
| Class | Triple incretin/glucagon agonist | Dual incretin agonist |
| Reported half-life | ≈ 6 days (130–160 h) | ≈ 5 days (≈ 120 h) |
| Backbone | Acylated 39-amino-acid analog | Acylated 39-amino-acid analog |
| Regulatory status | Investigational, phase 3 | Approved for clinical indications |
| Typical study focus | Energy expenditure and tri-pathway signalling | Dual-incretin signalling models |
| Vial sizes we supply | 5mg – 100mg | 5mg – 120mg |
| Form | Lyophilised powder | Lyophilised powder |
| Storage | 2–8 °C after mixing | 2–8 °C after mixing |
The receptor difference
Tirzepatide is a dual agonist: it binds the GIP receptor and the GLP-1 receptor. Those two incretin pathways converge on insulin secretion and gastric handling, and studying them together produces effects that neither pathway shows alone.
Retatrutide adds a third arm — glucagon receptor agonism. Glucagon signalling is classically opposed to insulin signalling, and adding it to an incretin agonist is counter-intuitive until you look at what glucagon does in the liver and in adipose tissue: it raises energy expenditure and drives hepatic lipid handling. The research interest in retatrutide is precisely this combination of incretin activity with a catabolic energy-expenditure arm, which is why it is treated as a distinct research tool rather than a stronger version of tirzepatide.
Pharmacokinetics and stability
Both peptides carry a fatty-acid chain that binds serum albumin, which is what stretches a half-life from the roughly two minutes of native GLP-1 out to the multi-day range. Published data put retatrutide at approximately six days and tirzepatide at approximately five, so both support weekly intervals in study designs.
In the vial, they behave the same. Both arrive as lyophilised powder, both are stable for extended periods when kept dry and frozen, and both become considerably more fragile once dissolved. Refrigerate reconstituted solution at 2–8 °C, protect it from light, and treat roughly 30 days as the in-use window.
Handling and reconstitution differences
The technique is identical for both compounds: bacteriostatic water run down the vial wall, gentle swirling, no shaking, visual inspection, refrigeration and labelling. What changes is the arithmetic, because the vial sizes differ. Our retatrutide line runs 5mg to 100mg and the tirzepatide line runs 5mg to 120mg, so the same water volume gives a different concentration between the two.
The retatrutide dosage chart and the peptide reconstitution calculator handle the conversion for either compound.
Choosing between them for a study
- Studying dual-incretin signalling in isolation? Tirzepatide gives you two pathways without a glucagon variable to control for.
- Studying energy expenditure or hepatic lipid handling? Retatrutide's glucagon arm is the reason it is in the protocol.
- Comparing generational analogs? Running both, plus semaglutide as a single-agonist reference, isolates what each additional receptor contributes.
- Working against a regulatory-status constraint? Tirzepatide has an approved clinical counterpart; retatrutide remains investigational.
Both compounds, COA verified
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Retatrutide vs tirzepatide FAQ
What is the difference between retatrutide and tirzepatide?
Retatrutide (LY3437943) is a triple agonist at the GIP, GLP-1 and glucagon receptors. Tirzepatide (LY3298176) is a dual agonist at the GIP and GLP-1 receptors only. The added glucagon receptor arm is the defining structural and pharmacological difference between them.
Is retatrutide stronger than tirzepatide?
They are not directly interchangeable, and we do not compare human outcomes. As research materials they differ in receptor coverage — three pathways versus two — which is why laboratories select between them by the signalling question being studied rather than by potency.
Do retatrutide and tirzepatide have different half-lives?
Both are long-acting acylated peptides. Published pharmacokinetic data put retatrutide at roughly six days and tirzepatide at roughly five days, so both support weekly study intervals in the literature.
Are retatrutide and tirzepatide reconstituted the same way?
The technique is identical: bacteriostatic water down the vial wall, gentle swirling, refrigerated storage after mixing. The arithmetic differs because the vial sizes differ — our retatrutide line runs 5mg to 100mg and the tirzepatide line runs 5mg to 120mg.
Which is approved — retatrutide or tirzepatide?
Tirzepatide has completed regulatory approval for clinical indications; retatrutide remains investigational and is in phase 3 trials. Neither compound sold here is approved for human or veterinary use — both are supplied for laboratory research only.
More retatrutide research resources
All products and information on this page are supplied strictly for in vitro laboratory research by qualified professionals. Retatrutide is an investigational compound and is not approved by the FDA for human or veterinary use. The figures here are reconstitution arithmetic, not dosing guidance — we do not provide therapeutic recommendations.