Retatrutide (research designation LY3437943) is an engineered 39-amino-acid peptide investigated in laboratory research as a simultaneous agonist of the GLP-1, GIP and glucagon receptors, the receptors central to incretin and metabolic-hormone signalling studies.

What does "triple agonist" mean?

In published research, "triple agonist" refers to a peptide engineered to engage three distinct receptors at once. For retatrutide those receptors are GLP-1R (glucagon-like peptide-1 receptor), GIPR (glucose-dependent insulinotropic polypeptide receptor) and GCGR (glucagon receptor).

How does retatrutide differ from tirzepatide and semaglutide?

Semaglutide is investigated as a single agonist of the GLP-1 receptor. Tirzepatide is investigated as a dual agonist of the GLP-1 and GIP receptors. Retatrutide adds a third target, the glucagon receptor (GCGR), giving it a triple-receptor profile in laboratory research.

What is retatrutide studied for in research?

Laboratory and preclinical research has examined retatrutide as a triple agonist of the GLP-1, GIP and glucagon receptors, with reported research contexts including incretin-pathway signalling, energy-expenditure readouts, and glucose-regulation pathways in cellular and animal models. Findings are experimental and should not be interpreted as demonstrated therapeutic effects in humans.

Is PepDirect's retatrutide sold for human use?

No. PepDirect supplies retatrutide in laboratory research formats only. It is not marketed as a medicine, food supplement, cosmetic or product for human or veterinary use.

↳ Research overview

What is Retatrutide?

Retatrutide (research designation LY3437943) is a 39-amino-acid engineered peptide investigated in laboratory research as a simultaneous agonist of three metabolic-hormone receptors, the glucagon-like peptide-1 receptor (GLP-1R), the glucose-dependent insulinotropic polypeptide receptor (GIPR) and the glucagon receptor (GCGR). This triple-receptor profile is what published research literature refers to when it describes retatrutide as a "triple agonist".

For laboratory research use only. PepDirect supplies retatrutide in research formats only.

§ The molecule

What retatrutide is

Research designation: LY3437943.
Peptide class: engineered incretin / metabolic-hormone-receptor triple agonist.
Structure: 39-amino-acid peptide with a fatty-acid modification investigated for its pharmacokinetic profile in preclinical research.
Molecular formula: C₂₂₁H₃₄₂N₄₆O₆₈.
Molecular weight: 4731.33 g/mol.
Receptors engaged: GLP-1R, GIPR and GCGR.

§ Triple-receptor profile

The three receptors: GLP-1R, GIPR and GCGR

GLP-1R

Glucagon-like peptide-1 receptor

An incretin-hormone receptor investigated in research on glucose-dependent insulin secretion and metabolic signalling. Also the sole target of single-agonist research peptides such as semaglutide.

GIPR

Glucose-dependent insulinotropic polypeptide receptor

A second incretin-hormone receptor investigated alongside GLP-1R. Dual GLP-1R/GIPR research peptides such as tirzepatide are studied for their combined incretin-pathway signalling.

GCGR

Glucagon receptor

The third receptor engaged by retatrutide. Adding GCGR activity distinguishes it from GLP-1/GIP dual agonists and is investigated in research on energy-expenditure and glucose-metabolism pathways.

These receptor descriptions summarise mechanistic research directions rather than demonstrated outcomes in humans.

§ Comparative peptides

Retatrutide vs semaglutide vs tirzepatide

Research peptide	Receptor profile	Class
Semaglutide	GLP-1R	Single agonist
Tirzepatide	GLP-1R + GIPR	Dual agonist
Retatrutide	GLP-1R + GIPR + GCGR	Triple agonist

All three are supplied by PepDirect as research-grade laboratory formats. The comparison summarises receptor-profile research and is not a therapeutic recommendation.

§ Research themes

Why researchers study retatrutide

Triple-receptor pharmacology

Retatrutide is investigated in laboratory research as a simultaneous agonist of GLP-1R, GIPR and GCGR, the first engineered peptide with this triple-target profile to enter published research literature.

Incretin-pathway signalling

GLP-1 and GIP are incretin hormones central to research on glucose-dependent insulin secretion. Retatrutide's activity at both receptors is examined alongside earlier single- and dual-agonist research peptides.

Glucagon receptor engagement

Adding GCGR activity distinguishes retatrutide from GLP-1/GIP dual agonists. Published research examines how simultaneous glucagon-receptor engagement affects experimental energy-expenditure and glucose-metabolism readouts.

Engineered 39-amino-acid peptide

Retatrutide (LY3437943) is a 39-residue engineered peptide with a fatty-acid modification investigated for its pharmacokinetic profile in preclinical research.

Comparative peptide research

Laboratory research compares retatrutide against single-receptor (GLP-1R only, e.g. semaglutide) and dual-receptor (GLP-1R + GIPR, e.g. tirzepatide) research peptides to characterise the contribution of each receptor arm.

Metabolic-signalling readouts

Published research on retatrutide reports readouts across incretin signalling, energy-expenditure pathways, and glucose regulation in cellular and preclinical models.

These themes reflect mechanistic research directions rather than demonstrated outcomes in humans.

§ Formats in PepDirect's catalog

Retatrutide in PepDirect's catalog

PepDirect currently supplies retatrutide in two research formats. Which format a laboratory chooses is a workflow decision, not a dosing recommendation.

Raw Vial

Retatrutide Raw Vial

Supplied as a lyophilised powder in a sealed vial. Requires reconstitution before laboratory use.

View Retatrutide Raw Vial →

Pen Kit

Retatrutide 40mg Pen Kit

Supplied pre-reconstituted in a dial-a-dose research pen format. No reconstitution step.

View Retatrutide 40mg Pen Kit →

§ Reference identity

Key chemical identity

Compound name: Retatrutide
Research designation: LY3437943
CAS Number: 2381089-83-2
Molecular formula: C₂₂₁H₃₄₂N₄₆O₆₈
Molecular weight: 4731.33 g/mol
Amino-acid count: 39-residue engineered peptide

Lot-specific handling, purity and storage information for purchasable product formats remains governed by the individual product page and its lot-specific Certificate of Analysis.

§ Research references

Selected research references

Retatrutide (LY3437943), Triple hormone-receptor agonist research overviewPubMed · Rosenstock et al.
Pharmacological characterisation of LY3437943, a novel triple GLP-1, GIP and glucagon receptor agonistPubMed · Coskun et al.
Retatrutide, Phase 2 laboratory research readouts in metabolic pathway signallingPubMed · Jastreboff et al.
GLP-1, GIP and glucagon receptors, incretin and metabolic signalling reviewPubMed · Müller et al.

§ FAQ

Frequently asked questions

What is retatrutide?: Retatrutide (research designation LY3437943) is an engineered 39-amino-acid peptide investigated in laboratory research as a simultaneous agonist of the GLP-1, GIP and glucagon receptors, the receptors central to incretin and metabolic-hormone signalling studies.
What does "triple agonist" mean?: In published research, "triple agonist" refers to a peptide engineered to engage three distinct receptors at once. For retatrutide those receptors are GLP-1R (glucagon-like peptide-1 receptor), GIPR (glucose-dependent insulinotropic polypeptide receptor) and GCGR (glucagon receptor).
How does retatrutide differ from tirzepatide and semaglutide?: Semaglutide is investigated as a single agonist of the GLP-1 receptor. Tirzepatide is investigated as a dual agonist of the GLP-1 and GIP receptors. Retatrutide adds a third target, the glucagon receptor (GCGR), giving it a triple-receptor profile in laboratory research.
What is retatrutide studied for in research?: Laboratory and preclinical research has examined retatrutide as a triple agonist of the GLP-1, GIP and glucagon receptors, with reported research contexts including incretin-pathway signalling, energy-expenditure readouts, and glucose-regulation pathways in cellular and animal models. Findings are experimental and should not be interpreted as demonstrated therapeutic effects in humans.
What is the difference between PepDirect's Retatrutide Raw Vial and Pen Kit?: The Raw Vial is supplied as a lyophilised (freeze-dried) powder in a sealed vial and requires reconstitution before laboratory use. The Pen Kit is supplied pre-reconstituted in a dial-a-dose research pen, removing the reconstitution step from the laboratory workflow. Both are supplied by PepDirect exclusively for laboratory research use.
Is PepDirect's retatrutide sold for human use?: No. PepDirect supplies retatrutide in laboratory research formats only. It is not marketed as a medicine, food supplement, cosmetic or product for human or veterinary use.

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