Online ordering is open. Ships in 1 to 2 business days. Tracked 2-day shipping, plain box. Every compound third-party tested

For laboratory and research use only. Not for human or veterinary use.
SBz Industries

Retatrutide vs Tirzepatide:
the difference in plain English

Same company, same family of molecules. The difference is how many hormone receptors each one switches on: tirzepatide two, retatrutide three.

The short answerWhat the research looked at
3 vs 2receptors switched on
2022 vs 2018discovery paper
$45 vs $45from, per vial here

The short answer

Tirzepatide opens two doors. Retatrutide opens three.

The body uses hormones as messages, and each message has its own lock on the outside of a cell, called a receptor. When the right key turns the lock, the cell changes what it is doing.

Tirzepatide is a lab-made key that fits two locks: the receptors for GLP-1 and GIP, two hormones the gut releases after you eat. Retatrutide fits those same two plus a third: the receptor for glucagon, a hormone made in the pancreas that works mainly on the liver.

That third lock is the whole difference, and it is why you see tirzepatide called a dual agonist and retatrutide called a triple agonist. Both came out of the same Eli Lilly research program, four years apart [2] [1].

A tray of labelled research vials.

Side by side

The two compounds, compared

RetatrutideTirzepatide
Short nameRetaTirz
Development codeLY3437943LY3298176
Receptors it switches onGLP-1, GIP and glucagonGLP-1 and GIP
Called aTriple agonistDual agonist
Developed byEli LillyEli Lilly
Discovery paper2022, Cell Metabolism2018, Molecular Metabolism
Where it standsIn clinical developmentActive ingredient in approved prescription medicines
CAS number2381089-83-22023788-19-2
Sizes here10 mg, 30 mg, 60 mg10 mg, 30 mg, 60 mg
Price here, from$45$45
StoragePowder in the freezer at minus 20 C, away from light. Once mixed, in the fridge at 2 to 8 C.

What is sold here is research material, not the prescription medicines. Prices are for a single vial of the smallest size.

The lab research

What each one has been studied in

In plain terms, with a link to every paper. The thing to notice is what each study was done in: cells in a dish, animal tissue, mice, or people.

Tirzepatide

Two receptors

The discovery

Eli Lilly scientists described it in 2018 as a peptide with a fatty acid attached, a chemical change that keeps it in circulation longer. They tested it in cells carrying each receptor, then in mice, then in a first small study in people [2].

How it works on each receptor

A 2020 study measured how strongly tirzepatide switches on each receptor in cells grown to carry them. It works harder on the GIP receptor than on the GLP-1 receptor, which is what the paper means by "imbalanced." At the GLP-1 receptor it triggers some signals inside the cell more than others, which is what "biased" means [3].

What it looks like in the receptor

A 2022 structure study produced detailed pictures of tirzepatide sitting in each of its two receptors, to see how one molecule can fit two different locks [4]. A 2024 study looked at what happens in fat cells when the GIP receptor stays switched on for a long time, using human fat cells in a dish and mice [5].

Retatrutide

Three receptors

The discovery

Described by Eli Lilly scientists in 2022. In cells it switched on the glucagon and GLP-1 receptors about equally and the GIP receptor more strongly. The team then worked in mice and ran a first small study in people [1].

Why the third receptor gets studied

Glucagon receptors sit on more than liver cells, including in the heart. A 2025 German study took heart tissue from mice, kept it beating in an organ bath, and measured whether retatrutide changed how hard and how fast it beat [6].

Side by side with tirzepatide

A 2026 study from a Japanese research company gave mice bred without the MC4R gene one of three compounds for 21 days: semaglutide, tirzepatide or retatrutide [7]. It is one of the few papers that puts the two in the same experiment.

Reading the research

Three things to check in any paper on these two

Who ran it. Most of the foundational work on both compounds comes from Eli Lilly, the company that makes them. That is normal for a new molecule, and it is worth knowing when you read it.

What it was done in. "Studied" can mean cells in a dish, a strip of mouse heart, a group of mice, or thousands of people. Those are very different amounts of evidence.

Which molecule. Semaglutide, tirzepatide and retatrutide often turn up in the same paper. Check which result belongs to which compound before drawing anything from it.

A person reading a printed laboratory report.

For the lab

Buying either one for research

Both are sold here as freeze-dried powder in 10 mg, 30 mg, 60 mg vials, tested by an independent lab. Each product page shows the sizes, the price and the certificate status. The rest of the family, including the amylin analogs cagrilintide and eloralintide, is in the GLP-1 research peptides category.

If you are new to working with freeze-dried peptides, the guides on reconstitution, bacteriostatic water and storage cover the handling side.

Questions

Common questions

What is the difference between retatrutide and tirzepatide?

The number of hormone receptors each one switches on. Tirzepatide works on two, the GLP-1 and GIP receptors. Retatrutide works on those two plus a third, the glucagon receptor. Both came out of the same Eli Lilly research program.

What do Reta and Tirz mean?

Short names. Reta is retatrutide and Tirz is tirzepatide. In papers you will also see the development codes: LY3437943 for retatrutide and LY3298176 for tirzepatide.

Why is retatrutide called a triple agonist?

An agonist is a molecule that switches a receptor on. Retatrutide switches on three different receptors, GLP-1, GIP and glucagon, so it is a triple agonist. Tirzepatide switches on two, so it is a dual agonist.

Which one is newer?

Retatrutide. The tirzepatide discovery paper came out in 2018 and the retatrutide one in 2022, both from Eli Lilly scientists.

Is this the same as the prescription medicine?

No. Tirzepatide is the active ingredient in approved prescription medicines, which are made and released under their own licences. Retatrutide is still in clinical development. What is sold here is research material for laboratory use only.

Why does this page not say what the human trials found?

Because those results are about medicines given to patients, and we sell research material. Telling you what happened to people in those trials would read as a reason to use these compounds on yourself, and nothing we sell is for that.

What does research use only mean here?

Both are sold for laboratory research and nothing else. They are not drugs or supplements, and they are not for human or veterinary use.

Sources

Every study mentioned on this page

Each one links to its record on PubMed, the US National Library of Medicine database. Checked on 29 September 2026.

  1. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of conceptCoskun and colleagues, Eli Lilly and Company. Cell Metabolism, 2022. The retatrutide discovery paper: receptor tests in cells, then mice, then a first small study in people.
  2. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of conceptCoskun and colleagues, Eli Lilly and Company. Molecular Metabolism, 2018. The tirzepatide discovery paper: cell tests, then mice, then a first study in people.
  3. Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonistWillard and colleagues, Eli Lilly, Duke University and the University of Copenhagen. JCI Insight, 2020. Cells grown to carry each receptor. How strongly tirzepatide switches each one on, and which signals it triggers.
  4. Structural determinants of dual incretin receptor agonism by tirzepatideSun and colleagues, ConfometRx and Eli Lilly. Proceedings of the National Academy of Sciences, 2022. Structure work: pictures of tirzepatide sitting in each of its two receptors.
  5. Tirzepatide modulates the regulation of adipocyte nutrient metabolism through long-acting activation of the GIP receptorRegmi and colleagues, Eli Lilly and Leiden University Medical Center. Cell Metabolism, 2024. Human fat cells in a dish, and mice.
  6. Contractile effects of retatrutide in isolated mouse atrial preparationsNeumann and colleagues, Martin Luther University Halle-Wittenberg. Naunyn-Schmiedeberg's Archives of Pharmacology, 2025. Heart tissue taken from mice and kept beating in an organ bath.
  7. Efficacy of GLP-1 analog peptides, semaglutide, tirzepatide, and retatrutide on MC4R deficient obesity and their comparisonHitaka and colleagues, Axcelead Drug Discovery Partners. International Journal of Obesity, 2026. Mice bred without the MC4R gene, given one of three compounds for 21 days.

In the catalog

Retatrutide and tirzepatide

For laboratory research use only. Every vial ships in a plain box with a packing slip.

RetatrutideTirzepatide

Elsewhere

Also on this site

The laboratoryWho tests our compounds, and how to check a report with them.Research libraryMethod guides and the compound reference.Bacteriostatic water guideShelf life, volumes and what the preservative does.Reconstitution calculatorVolume to concentration, from peptide mass.GlossaryThe words on a certificate, defined.Supplier checklistFourteen checks to run on any supplier, this one included.
Fast dispatchShips in 1 to 2 business days
Plain packagingNo exterior branding
Tracked shippingTwo business days, flat rate
Third-party testedCertificate on every product page