Retatrutide vs Tirzepatide vs Semaglutide
Three incretin-class research compounds compared by receptor target, from single to triple agonism. For laboratory research reference only.
Product note: Of the three compounds compared here, only retatrutide is offered by Enhanced Research Compounds. Tirzepatide and semaglutide appear solely as reference comparators. This page concerns receptor pharmacology and assay design, not any physiological, glycaemic, or body-composition effect in humans.
Overview
Retatrutide, tirzepatide, and semaglutide are three peptide research compounds from the incretin / metabolic-hormone class, widely used as reference agonists in metabolic-pathway and GPCR signalling research. They are most usefully distinguished by the breadth of their receptor targets: semaglutide is a single GLP-1 receptor agonist, tirzepatide is a dual GIP/GLP-1 receptor agonist, and retatrutide is a triple GIP/GLP-1/glucagon receptor agonist.
All three are synthetic, fatty-acid-modified peptide analogues engineered for proteolytic stability and prolonged receptor engagement. This comparison is framed for laboratory reference only, as a way to understand how progressively broader receptor coverage (one to two to three receptors) is reflected in published in-vitro receptor pharmacology.
At a Glance
| Retatrutide | Tirzepatide | Semaglutide | |
|---|---|---|---|
| Receptor targets | Triple: GIP + GLP-1 + glucagon | Dual: GIP + GLP-1 | Single: GLP-1 only |
| Identifier | LY-3437943 | LY-3298176 | Semaglutide |
| Research context | Most recent; triple agonist | Established dual incretin agonist | Long-standing GLP-1 reference |
| Molecular class | Acylated multi-receptor peptide agonist | Acylated dual incretin agonist | Acylated GLP-1 analogue |
Each in Brief
Retatrutide (LY-3437943). A triple agonist peptide engineered to engage the glucagon (GCGR), GIP (GIPR), and GLP-1 (GLP-1R) receptors simultaneously. In published cell-based assays its relative potency differs by receptor. It is the broadest- coverage compound of the three and the focus of current incretin- class research interest. See the retatrutide research guide.
Tirzepatide (LY-3298176). A dual GIP/GLP-1 receptor co-agonist. Structural studies describe it as an imbalanced agonist that engages the GIP receptor more strongly than GLP-1R, with signalling bias at GLP-1R favouring cAMP generation over beta-arrestin recruitment. Included here as a reference comparator only.
Semaglutide. A single-target GLP-1 receptor agonist and acylated GLP-1 analogue. It serves as the canonical single- receptor reference point against which dual (tirzepatide) and triple (retatrutide) agonists are benchmarked. Included here as a reference comparator only.
Key Mechanistic Differences
The defining variable across the three is receptor-target breadth. The research value of the comparison lies in isolating what each additional receptor arm contributes in mechanistic models:
- Semaglutide (GLP-1 only) isolates GLP-1R signalling as a clean single-pathway control.
- Tirzepatide (GIP + GLP-1) adds the GIP receptor arm, enabling study of GIPR/GLP-1R co-activation and the receptor-bias phenomena reported in its structural literature.
- Retatrutide (GIP + GLP-1 + glucagon) adds the glucagon receptor (GCGR) on top, allowing researchers to probe how glucagon-receptor co-agonism interacts with the two incretin receptors in metabolic-pathway models.
This stepwise progression (one to two to three receptors) is a useful experimental ladder: it lets investigators attribute differences in in-vitro signalling (cAMP accumulation profiles, binding-affinity rank orders, biased-agonism readouts) to the specific receptor arm being added. This is a statement about receptor pharmacology and assay design only, not about any effect in humans.
Key Published Research
Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial
Jastreboff AM, et al. New England Journal of Medicine. 2023; 389:514-526
Phase-2 trial of the triple GIP/GLP-1/glucagon receptor agonist retatrutide (LY-3437943).
LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist: from discovery to clinical proof of concept
Coskun T, et al. Cell Metabolism. 2022; 34(9):1234-1247
The discovery and pharmacology paper establishing retatrutide's triple-receptor agonism and first-in-human PK/PD.
Frequently Asked Questions
What is the difference between retatrutide, tirzepatide, and semaglutide?
They differ in the number of receptors they target. Semaglutide is a single GLP-1 receptor agonist, tirzepatide is a dual GIP/GLP-1 receptor agonist, and retatrutide is a triple GIP/GLP-1/glucagon receptor agonist. Only retatrutide is offered by ERC.
What does "triple agonist" mean?
A triple agonist is a single peptide engineered to bind and activate three distinct receptors. For retatrutide (LY-3437943) those are the GIP receptor, the GLP-1 receptor, and the glucagon receptor.
Why use tirzepatide and semaglutide as comparators if ERC only sells retatrutide?
Because retatrutide's triple-receptor pharmacology is best interpreted against narrower-target references. The dual-target tirzepatide and single-target semaglutide act as a mechanistic ladder for the literature. They are reference points, not products ERC supplies.
Disclaimer: This information is compiled from published peer-reviewed literature and is provided for educational and research reference purposes only. It does not constitute medical advice. Retatrutide sold by Enhanced Research Compounds is intended exclusively for in-vitro research and laboratory use. It is not a therapeutic good, is not listed on the ARTG, and is not approved for human or animal consumption. Tirzepatide and semaglutide are referenced for comparison only and are not products offered by Enhanced Research Compounds.