Retatrutide vs Tirzepatide vs Semaglutide
Three generations of GLP receptor agonist research peptides — single-receptor, dual-receptor, and triple-receptor. Side-by-side mechanism, structure, and catalog availability.
| Attribute | Semaglutide | Tirzepatide | Retatrutide |
|---|---|---|---|
| Receptor activation | GLP-1R | GLP-1R + GIPR | GLP-1R + GIPR + GCGR |
| Generation | 1 (single) | 2 (dual) | 3 (triple) |
| Structure | GLP-1 analog (37 AA + fatty acid chain) | 39 AA synthetic peptide | 39 AA synthetic peptide |
| Selectivity profile | GLP-1 selective | ~5× GIP-favored | Roughly balanced GLP/GIP, lower GCGR |
| Research half-life | ~1 week | ~5 days | ~6 days |
| HPLC purity | ≥99% | ≥99% | ≥99% |
| Per-lot COA | Yes | Yes | Yes |
| Available sizes | 10 · 20 · 30 mg | 10 · 20 · 30 · 60 mg | 10 · 15 · 20 · 30 · 50 mg |
| Lowest price | $39 (10 mg) | $64 (10 mg) | $74 (10 mg) |
How to read this comparison
The GLP receptor agonist class has evolved through three engineering generations, each adding a new receptor target. The research utility of each compound depends on which pathway(s) you want to study.
Semaglutide — the GLP-1 reference standard
Semaglutide is a GLP-1 receptor analog with structural modifications (an albumin-binding fatty acid chain at position 26) that extend its research-model half-life from minutes (native GLP-1) to multi-day kinetics. Published binding assays show low picomolar EC50 values for GLP-1R activation with minimal cross-reactivity at GIPR or GCGR.
Use case in research: single-pathway specificity studies. Semaglutide is the cleanest tool when you want to isolate GLP-1R effects from related receptors.
Tirzepatide — dual GLP-1/GIP activation
Tirzepatide is a 39-amino-acid synthetic peptide engineered to activate both GLP-1R and GIPR simultaneously. Published binding data shows approximately 5× selectivity for GIPR over GLP-1R, but both receptors activate at research-relevant concentrations.
The dual-receptor design is based on research observations that combining GLP-1 and GIP receptor activation produces effects exceeding the sum of single-receptor activation alone — a synergy characterized in pancreatic β-cell research and adipocyte studies.
Use case: dual-pathway synergy studies.
Retatrutide — triple agonism including glucagon receptor
Retatrutide is a 39-amino-acid synthetic peptide that adds glucagon receptor (GCGR) activation to GLP-1 and GIP. Published binding data shows roughly equipotent activation of GLP-1R and GIPR with somewhat lower (but still significant) GCGR activation.
Adding glucagon receptor agonism engages hepatic energy expenditure pathways not activated by GLP-1 or GIP alone. The pharmacological hypothesis driving triple-agonist research is that this combined receptor profile produces effects beyond what dual agonism alone achieves.
Use case: triple-pathway integrated metabolism studies. Retatrutide is the only commercially available triple-agonist peptide in this class.
Practical research notes (same across the class)
Reconstitution: all three are typically supplied lyophilized. Standard ratio is 2 mL bacteriostatic water per 10 mg of peptide, producing a 5 mg/mL solution. See the reconstitution calculator for protocol-specific math.
Storage: lyophilized room-temp stable in transit; refrigerated 12–18 months; frozen 24+ months. Reconstituted: refrigerated 30–60 days.
QC: all three peptides are 37–39 amino acids long, putting them at the upper end of solid-phase peptide synthesis difficulty. Per-lot HPLC chromatograms are particularly important for this class because batch-to-batch variation is real even from a competent manufacturer. Matte’s COA library publishes chromatograms addressable by lot number.
Choosing for your protocol
- Single-receptor specificity → Semaglutide (cleanest, lowest cost)
- Dual-pathway synergy → Tirzepatide (GLP-1 + GIP co-activation)
- Triple-pathway integrated study → Retatrutide (only commercial option)
- Comparative class study → run all three in parallel; price-per-mg drops as dose increases
Full GLP class catalog: /shop/. Detailed research background: GLP receptor agonists research context.