Retatrutide: Research, Handling and Batch Documentation

Identity and research status

Also referred to as

LY3437943

Class

Synthetic 39 amino acid peptide, acylated

Molecular Formula

C221H342N46O68

Molecular Weight

4731.33 g/mol

CAS Number

2381089-83-2

Developer Code

LY3437943

Receptor Targets

GIP receptor, GLP-1 receptor, glucagon receptor

Backbone

GIP-based sequence with substitutions conferring GLP-1 and glucagon cross-reactivity

Half-life

Approximately 6 days, consistent with the once-weekly schedule used in trials

Prolongation Strategy

Fatty diacid acylation, giving reversible albumin binding

Regulatory Status

Investigational. Not approved by the FDA, EMA or Health Canada

Appearance

White lyophilised powder

Mechanism, in brief

Retatrutide is a single 39 amino acid peptide engineered to activate three receptors at once: the glucose-dependent insulinotropic polypeptide receptor (GIPR), the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR). Earlier incretin agents act at one or two of these. Adding the glucagon arm is what separates retatrutide pharmacologically, because glucagon receptor activation raises energy expenditure rather than only suppressing intake, so the compound acts on both sides of the energy balance equation instead of one.

1. Albumin binding. The fatty diacid substituent binds circulating albumin reversibly, which slows renal clearance and proteolysis and gives the molecule a terminal half-life of roughly six days.
2. GIPR activation. The dominant activity of the three. GIP receptor signalling in islet beta cells is glucose-dependent, and in adipose tissue it influences lipid handling and buffering capacity.
3. GLP-1R activation. Drives glucose-dependent insulin secretion, slows gastric emptying and acts at hypothalamic and hindbrain circuits that reduce food intake.
4. GCGR activation. The arm that distinguishes this compound. Hepatic glucagon receptor signalling increases energy expenditure and lipolysis and reduces hepatic fat, at the cost of a hyperglycaemic tendency the incretin arms must offset.
5. Net effect in the models studied. Reduced intake from the incretin arms combined with raised expenditure from the glucagon arm, which is the mechanistic argument offered for why the compound produced larger weight reductions in trials than single or dual agonists.

The full research write-up, including the findings behind each claim and the model each came from, is on the Retatrutide 10mg 10mg page.

Vial sizes available

Every size of Retatrutide Volta lists, in stock or not. Each is a separate catalogue page with its own batch number and specification table.

• Retatrutide 10mg 10mgBatch #: VPRT10100
  In stock
• Retatrutide 20mg 20mgBatch #: VPRT20100
  In stock
• Retatrutide 30mg 30mgBatch #: VPRT30100
  Restocking
• Retatrutide 5mg 5mgBatch #: VPRT5100
  Restocking

Purity and batch documentation

Volta's release specification is >99% (HPLC). That is a threshold we set. >99% is the specification every batch is released to. The figure on a certificate is what a laboratory measured for one lot.

• SideChain Analytics reported 99.7% by HPLC-MS/MS on September 16, 2026, lot VPRT20100.

  Covers the 20mg vial. Results relate to the sample as received and are not a measurement of the other fills.

  Read the certificateVerify on lab's website (Verify on SideChain Analytics's website, opens in a new tab)

Research on Retatrutide

Handling and stability

Regulatory context

United States

Not FDA-approved. Phase 3 TRIUMPH program ongoing (Eli Lilly). TRIUMPH-4 reported 28.7% body weight loss at 12 mg over 68 weeks. Seven Phase 3 readouts expected in 2026. Regulatory submission expected 2026; approval anticipated 2027-2028.

Canada

Not approved. Investigational.

United Kingdom

Not approved. Investigational.

• the legal status of research peptides in Canada
• Health Canada's regulatory position

Primary sources

1. Jastreboff AM, Kaplan LM, Frias JP, et al.. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. New England Journal of Medicine (2023). PMID 37366315
2. Rosenstock J, Frias J, Jastreboff AM, et al.. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial. The Lancet (2023). PMID 37385280
3. Coskun T, Urva S, Roell WC, et al.. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept. Cell Metabolism (2022). PMID 35985340
4. Bajaj HS, Welch M, et al.. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes. The Lancet (2026). PMID 42250575
5. Ruotolo G, Harris C, et al.. Retatrutide-Associated Improvements in Cardiovascular Risk Biomarkers in Adults With Obesity With or Without Type 2 Diabetes. Diabetes, Obesity and Metabolism (2026). PMID 42608321
6. Pearson MJ, Willency JA, et al.. Retatrutide and Lipid and Metabolite Profiles in Participants With Obesity With or Without Type 2 Diabetes. Journal of Clinical Endocrinology and Metabolism (2026). PMID 42135195
7. Wen Y, Lemen D, et al.. Decreases in circulating ANGPTL3/8 concentrations following retatrutide treatment parallel reductions in triglycerides. Diabetes, Obesity and Metabolism (2025). PMID 40726454
8. Briand F, Le Cudennec C, et al.. Retatrutide Shows Multiple Metabolic Benefits in Diet-Induced Obese MASH Mouse and Hamster Models. Obesity (Silver Spring) (2026). PMID 41741376