Semaglutide vs Tirzepatide vs Retatrutide
A side-by-side look at how these three GLP-1 receptor agonist research compounds differ in mechanism and molecular structure — a technical reference, not a recommendation for any one compound over another.
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Receptor mechanism | Single-receptor agonist — GLP-1 receptor only | Dual-receptor agonist — GIP and GLP-1 receptors | Triple-receptor agonist — GIP, GLP-1, and glucagon receptors |
| Designation | Semaglutide | Tirzepatide (LY3298176) | Retatrutide (LY3437943) |
| CAS number | 910463-68-2 | 2023788-19-2 | 2381089-83-2 |
| Approx. molecular weight | ~4113.6 g/mol | ~4813.5 g/mol | ~4731.3 g/mol |
| Amino acid backbone | 31 amino acids, C18 fatty diacid chain | 39 amino acids, C20 fatty diacid chain | 39 amino acids, fatty acid chain |
| Reported terminal half-life† | ~1 week | ~5 days | ~5.6–7.5 days (range varies by study) |
| What the literature examines | Glucose regulation, insulin signaling, satiety pathways, body-weight models | Insulin signaling, glucose regulation, lipid metabolism, body-composition models | Glucose handling, energy expenditure, lipid metabolism, body-composition models |
| Purity (this site) | ≥98%, HPLC + mass spec, third-party COA | ≥98%, HPLC + mass spec, third-party COA | ≥98%, HPLC + mass spec, third-party COA |
† Half-life figures are approximate values reported in published pharmacokinetic research literature on each compound, not measurements performed by Send It Peptides. Our own Certificates of Analysis verify batch identity and purity — see the lab results page.
One receptor, two receptors, three receptors
These three GLP-1 compounds form a single-, dual-, and triple-agonist series — each adding one more receptor target to the last.
Semaglutide
Single agonist · GLP-1
Semaglutide is the long-acting GLP-1 agonist most metabolic work gets measured against.
Tirzepatide
Dual agonist · GIP / GLP-1
Tirzepatide hits two receptors from one molecule: GIP and GLP-1.
Retatrutide
Triple agonist · GIP / GLP-1 / glucagon
Retatrutide (LY3437943) is the triple agonist — GIP, GLP-1 and glucagon receptors, all from one molecule.
From single agonist to triple agonist
Semaglutide engages a single target, the GLP-1 receptor, and is the most extensively published reference compound in this class — decades of incretin-receptor research trace back to single-agonist molecules like it.
Tirzepatide adds a second target, the GIP receptor, alongside GLP-1. This dual-agonist design is studied for how co-activating two complementary incretin pathways changes the signaling picture compared with a single-receptor molecule.
Retatrutide adds a third target, the glucagon receptor, on top of GIP and GLP-1. Its triple-receptor design is the most recent addition to this research series and is examined for how the added glucagon-receptor pathway interacts with the other two.
All three are synthetic peptides supplied as lyophilized powder for laboratory reconstitution, independently tested by an independent third-party laboratory, and sold strictly for in-vitro research use. None of the identifiers, structural data, or literature summaries on this page are a recommendation to use any one compound over another — that determination belongs to a qualified researcher's own study design, not to us.