RETA-3 20mg

Our RETA-3 20mg vial holds 20mg of lyophilized RETA-3 (retatrutide), a GIP, GLP-1 and glucagon receptor agonist. It’s sold for laboratory research only.

RETA-3 is our code name for retatrutide. The compound inside the vial is retatrutide, and everything below describes it.

What is RETA-3 (retatrutide)?

Retatrutide (LY3437943) is a single 39-amino-acid peptide from Eli Lilly that acts on three receptors at once: GIP, GLP-1 and glucagon. That makes it the first triple hormone receptor agonist to reach late-stage trials.

A fatty acid side chain lets it bind albumin in the blood, which stretches its half-life to about six days and makes once-weekly study possible. It isn’t approved anywhere yet.

How RETA-3 works

Retatrutide hits three receptors with one peptide: GIP, GLP-1 and glucagon. The first two are incretins that boost glucose-dependent insulin release and, in GLP-1’s case, curb appetite and slow stomach emptying.

The glucagon part is the unusual bit. Glucagon raises energy expenditure and pushes the liver to burn fat, so pairing it with the incretins is meant to work on both sides of energy balance. That’s the main reason researchers compare it with the dual and single agonists.

RETA-3 20mg specifications

• Compound: RETA-3 (retatrutide)
• Also known as: LY3437943
• CAS number: 2381089-83-2
• Molar mass: 4,731.3 g/mol
• Structure: 39 amino acids with a fatty diacid side chain
• Amount: 20mg per vial
• Form: lyophilized (freeze-dried) powder
• Label: compound name and amount printed on every unit
• SKU: RETA3-20
• Use: laboratory research only

Published RETA-3 studies

Jastreboff and colleagues reported the phase 2 obesity trial in the New England Journal of Medicine in 2023. At the highest dose, average weight loss reached 24.2% at 48 weeks, the largest figure any incretin compound had shown at that stage.

A substudy in Nature Medicine (Sanyal and colleagues, 2024) found large drops in liver fat, and a separate phase 2 trial in type 2 diabetes was published in The Lancet in 2023. Lilly’s phase 3 TRIUMPH program is testing it in obesity, diabetes, knee osteoarthritis and sleep apnea.

To read the papers yourself, start with this PubMed search for Retatrutide.

RETA-3 compared with similar compounds

Labs choosing RETA-3 20mg usually weigh it against a few close relatives. RETA-3 hits GLP-1, GIP and glucagon receptors, the triple agonist with the biggest phase 2 numbers so far, while:

• SEMA-1 acts on the GLP-1 receptor only and lasts about a week, the most studied compound in the group
• TIRZ-2 adds GIP receptor activity to GLP-1, a dual agonist with larger weight effects than semaglutide in trials
• Survodutide is another GLP-1 and glucagon dual agonist, in phase 3 for obesity and the liver disease MASH
• CAG-4 works through amylin receptors instead of incretins, often studied next to or with semaglutide

The main difference between these compounds is which receptors they hit. Pick the one that matches the receptor question in your study, and use the others as comparisons. See them all on our GLP-1 peptides page.

How to reconstitute RETA-3 20mg

Concentration is the amount in the vial divided by the volume of water you add. With 20mg of powder in this vial:

• 1mL of bacteriostatic water gives 20mg/mL
• 2mL of bacteriostatic water gives 10mg/mL
• 3mL of bacteriostatic water gives 6.67mg/mL

Choose the volume that suits your measurements. Mark the vial with the concentration and date so nobody has to guess later.

Bacteriostatic water is the usual choice, and acetic acid helps with peptides that won’t dissolve in water alone. Add it slowly so it runs down the side of the vial, then swirl or roll until everything dissolves. Shaking can shear peptide chains. Skip it.

RETA-3 20mg storage and shelf life

Freeze-dried RETA-3 20mg handles room temperature fine during shipping, but for anything longer keep it in a freezer at -20°C, away from light. Once mixed, keep it in the fridge at 2 to 8°C and use it within about four weeks.

Running several vials at once? Our 10 vial kit case holds up to ten vials upright in separate wells under a clear lid, which keeps a fridge shelf tidy and the labels easy to read.

Checking your RETA-3 20mg

Every RETA-3 20mg vial carries a printed label with the compound name and amount, so you always know what you’re holding. If your lab needs batch paperwork for its records, contact Peptira support before you order and ask what’s available for the current batch.

If you verify incoming material yourself, the standard methods are HPLC for purity and mass spectrometry for identity. HPLC splits the sample and reports the main peak as a percentage, while mass spec confirms that peak has the right molecular weight.

Keep a record of which vial went into which experiment. Matching results to material is the simplest way to rule it out when an experiment doesn’t behave.

Choosing an RETA-3 strength

• RETA-3 10mg: $99.00, about $9.90 per mg
• RETA-3 20mg (this page): $139.00, about $6.95 per mg
• RETA-3 30mg: $179.00, about $5.97 per mg

For longer projects a larger vial like RETA-3 20mg means fewer vials to mix and fewer reorders.

Other GLP-1 peptides to look at

• TIRZ-2 60mg, a GIP/GLP-1 agonist
• CAG-4 10mg, an amylin analog
• SEMA-1 10mg, a GLP-1 agonist
• Survodutide 10mg, a GLP-1/glucagon agonist
• SLU-PP-332 BAM-15 Capsules, a capsule format

Browse the full GLP-1 peptides and weight loss peptides range, see every vial on our research peptides page or head back to the Peptira home page.

Common questions about RETA-3 20mg

How much is in the RETA-3 20mg vial?

20mg of freeze-dried powder. The amount is printed on the label.

What is RETA-3?

RETA-3 is our catalog name for retatrutide. The vial holds retatrutide as freeze-dried powder.

Where can I buy RETA-3 20mg?

Right here at Peptira. Add RETA-3 20mg to the cart on this page and it ships free worldwide.

What do I mix RETA-3 20mg with?

Sterile bacteriostatic water is the usual choice. The reconstitution section above shows the concentration for each volume.

How should I store it?

Keep sealed vials in the freezer at -20°C. Once mixed, refrigerate at 2 to 8°C and use within about 28 days.

Order RETA-3 20mg today

Order RETA-3 20mg now for $139.00. It’s in stock, code PEPTIRA10 takes 10% off at checkout, and we ship free to the US, Canada, Europe and Australia. Choose crypto at checkout for an extra discount.

Need more for the same project? See the rest of our GLP-1 peptides and weight loss peptides, or go back to the Peptira home page.

For laboratory research use only. Not for human or veterinary use. These statements have not been evaluated by the FDA.