A technical comparison of three GLP-1 receptor-targeting compounds: single, dual, and triple agonist mechanisms in preclinical and clinical research.
Written by the Peptide Labs Research Team
GLP-1 receptor agonists represent one of the most actively researched compound classes in metabolic science. Three compounds (semaglutide, tirzepatide, and retatrutide) differ fundamentally in their receptor targeting profile, creating distinct research contexts for each.
| Property | Semaglutide | TirzepatideLY3298176 | RetatrutideLY3437943 |
|---|---|---|---|
| Class | Incretin mimetic | Incretin mimetic | Incretin mimetic |
| Target | GLP-1 | GLP-1 + GIP | GLP-1 + GIP + Glucagon |
| Structure | GLP-1 analogue with C18 diacid fatty acid chain | LY3298176, dual GIP/GLP-1 receptor agonist | LY3437943, triple receptor agonist |
| Molecular weight | — | ~4813.5 Da | ~5766 Da |
| Formula | — | C₂₂₅H₃₄₈N₄₈O₆₈ | C₂₄₉H₃₉₆N₆₈O₇₂ |
| CAS number | — | 2023788-19-2 | 2381089-83-2 |
| Half-life | ~7 days | ~5 days | Not established |
| Human evidence | Approved drug (some jurisdictions) | Approved drug (some jurisdictions) | Phase 2-3 trial data |
| Studied in |
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| Notes | Not stocked. Included because the comparison is meaningless without it. | — | Investigational. Not an approved medicine in any jurisdiction. |
| Availability | Not stocked | In catalogue$109.99 | In catalogue$129.99 |
Molecular data from the certificate of analysis for each batch. Half-life and evidence level reflect the published literature cited in our research articles. Research use only.
| Compound | GLP-1 | GIP | Glucagon |
|---|---|---|---|
| Semaglutide | ✓ | — | — |
| Tirzepatide | ✓ | ✓ | — |
| Retatrutide | ✓ | ✓ | ✓ |
Mechanism: Selective GLP-1 receptor agonist
Structure: Modified GLP-1 analogue with fatty acid chain (C18 diacid)
Half-life: ~7 days (suitable for once-weekly dosing in clinical settings)
Semaglutide acts exclusively at GLP-1 receptors, stimulating insulin secretion, suppressing glucagon, and slowing gastric emptying. The single-receptor approach creates a well-characterised pharmacological profile.
Mechanism: GLP-1/GIP dual receptor agonist
Structure: Novel synthetic peptide incorporating both GLP-1 and GIP activity
Half-life: ~5 days
Tirzepatide's additional GIP receptor activity produces additive effects compared to GLP-1 alone in research models. GIP signalling may enhance insulin sensitivity independently of GLP-1 pathways.
Mechanism: GLP-1/GIP/Glucagon triple receptor agonist
CAS: 2381089-83-2
Structure: LY3437943, novel triagonist peptide
Retatrutide adds glucagon receptor agonism to the dual GLP-1/GIP profile. In preclinical models, glucagon receptor activation increases energy expenditure via hepatic gluconeogenesis and thermogenic pathways, potentially amplifying metabolic effects beyond dual agonism.
Each compound offers distinct research utility:
All three compound classes are available for in-vitro research from Peptide Labs. View our Fat Loss category for current stock and COA data.
Disclaimer: All comparisons are based on published preclinical and clinical research literature. Information is for educational purposes only. Not medical advice.
What research peptides actually cost in Australia in 2026 — price ranges by compound class, how to work out cost per mg, and why two listings for the 'same' vial can differ by four times.
Buying GuidesWhat Retatrutide costs per vial, per mg and across the 10mg/20mg/30mg range from Australian research suppliers in 2026, and why the price doesn't scale in a straight line with vial size.
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