GLP-1 Agonist Comparison: Semaglutide vs Tirzepatide vs Retatrutide vs Cagrilintide vs Orforglipron
Head-to-head comparison of GLP-1 receptor agonists and next-generation metabolic peptides — efficacy, mechanisms, side effects, and clinical trial data.
The GLP-1 receptor agonist class has expanded rapidly from single-target peptides to multi-receptor agonists and oral formulations. This article provides a head-to-head comparison of the major compounds based on published clinical trial data.
Head-to-Head Comparison Table
| Property | Semaglutide | Tirzepatide | Retatrutide | Cagrilintide | Orforglipron |
|---|---|---|---|---|---|
| Type | GLP-1 RA | Dual GIP/GLP-1 RA | Triple GIP/GLP-1/GCGR agonist | Amylin analog | Non-peptide GLP-1 RA |
| Route | SC injection or oral | SC injection | SC injection | SC injection | Oral (small molecule) |
| Frequency | Weekly | Weekly | Weekly | Weekly | Daily (oral) |
| Max Weight Loss | ~15-17% (STEP trials) | ~22.5% (SURMOUNT-1) | ~24% (Phase 2, 48 wk) | ~15.6% (with semaglutide) | ~14.7% (Phase 2) |
| HbA1c Reduction | ~1.5-1.8% | ~2.0-2.3% | ~2.0% (Phase 2) | Not primary endpoint | ~1.4-1.6% (Phase 2) |
| Receptor Targets | GLP-1R | GIP-R + GLP-1R | GIP-R + GLP-1R + GCGR | CALCR (amylin) | GLP-1R |
| FDA Status | Approved (Ozempic, Wegovy, Rybelsus) | Approved (Mounjaro, Zepbound) | Phase 3 | Phase 3 (CagriSema) | Phase 3 |
| GI Side Effects | Nausea 20-44% | Nausea 12-24% | Nausea ~25% | Nausea ~25% | Nausea ~25-35% |
Mechanism Comparison
Single-Target: Semaglutide & Orforglipron
Semaglutide is an acylated GLP-1 analog with albumin binding for weekly duration. It activates GLP-1R to slow gastric emptying, increase insulin secretion, suppress glucagon, and reduce appetite via hypothalamic signaling. Orforglipron achieves the same receptor activation as a non-peptide small molecule, enabling oral dosing without absorption enhancers.
Dual-Target: Tirzepatide
Tirzepatide activates both GIP and GLP-1 receptors. The GIP receptor component enhances insulin sensitivity and may contribute to greater weight loss compared to GLP-1-only agonists. The SURPASS trials demonstrated superiority over semaglutide 1mg for HbA1c reduction.
Triple-Target: Retatrutide
Retatrutide adds glucagon receptor (GCGR) agonism to the GIP/GLP-1 dual mechanism. Glucagon receptor activation increases energy expenditure and hepatic fat oxidation. The Phase 2 trial showed the highest weight loss of any metabolic peptide — up to 24% at 48 weeks.
Amylin Pathway: Cagrilintide
Cagrilintide is a long-acting amylin analog that acts on calcitonin receptors in the brainstem to reduce appetite through a pathway distinct from GLP-1. It is being developed in combination with semaglutide (CagriSema) to achieve additive weight loss through complementary mechanisms.
Key Clinical Trial Results
Weight Loss Efficacy (Ranked)
- Retatrutide — 24.2% at 48 weeks (12mg dose, Phase 2)
- Tirzepatide — 22.5% at 72 weeks (15mg dose, SURMOUNT-1)
- Semaglutide — 16.9% at 68 weeks (2.4mg dose, STEP 1)
- CagriSema — 15.6% at 32 weeks (Phase 2)
- Orforglipron — 14.7% at 36 weeks (Phase 2)
Cardiovascular Outcomes
- Semaglutide: SELECT trial — 20% reduction in MACE (cardiovascular death, MI, stroke) in overweight/obese adults without diabetes
- Liraglutide: LEADER trial — 13% MACE reduction in T2D patients
- Tirzepatide: SURPASS-CVOT ongoing; interim data positive
- Retatrutide: No CV outcomes data yet (Phase 3 ongoing)
Side Effect Profile Comparison
| Side Effect | Semaglutide | Tirzepatide | Retatrutide | Orforglipron |
|---|---|---|---|---|
| Nausea | ++ | + to ++ | ++ | ++ |
| Diarrhea | + | ++ | + | ++ |
| Vomiting | + | + | + | + |
| Constipation | + | + | + | + |
| Injection site reactions | + | + | + | N/A (oral) |
| Heart rate increase | + | Minimal | + | + |
+ = mild/moderate incidence; ++ = moderate/higher incidence
Choosing Between Agents: Research Considerations
Maximum efficacy: Retatrutide shows the highest weight loss in Phase 2 data, though Phase 3 confirmation is pending.
Established evidence: Semaglutide has the most extensive clinical trial program with cardiovascular outcomes data.
Oral route preferred: Orforglipron is the only non-peptide oral option; oral semaglutide (Rybelsus) requires fasting and SNAC co-formulation.
Complementary mechanisms: CagriSema combines GLP-1 and amylin pathways for potentially additive effects through distinct CNS circuits.
See Also
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Peptide Stacking Guide: Research-Based Combinations
Comprehensive peptide stacking reference — healing, growth hormone, nootropic, longevity, metabolic, and cosmetic stacks with research rationale for each combination.