Retatrutide vs Setmelanotide
Side-by-Side Comparison
| Attribute | Retatrutide | Setmelanotide |
|---|---|---|
| Category | Metabolic / Triple Agonist | Metabolic / MC4R Agonist |
| Mechanism | Retatrutide simultaneously activates three receptors: GLP-1 (reduces appetite, slows gastric emptying, improves insulin secretion), GIP (enhances insulin sensitivity, glucose control), and glucagon... | Setmelanotide is a selective MC4R agonist that re-establishes signaling in the hypothalamic leptin-melanocortin pathway. |
| Evidence Rating | B — Phase III / NDA Filed | A — FDA Approved |
| Clinical Status | Phase 3 clinical trials (Eli Lilly TRIUMPH program) | FDA-approved (Imcivree, November 2020 for POMC/PCSK1/LEPR deficiency obesity; June 2022 for BBS obesity) |
| Safety Profile | GI side effects (dose-related, 13-63% across dose groups): nausea, vomiting, diarrhea, constipation; mostly mild to moderate; GI events partially mitigated with lower starting dose (2 mg vs 4 mg initial dose) | Common (>=10%): injection site reactions (45%), skin hyperpigmentation (75%, due to MC1R activation), spontaneous penile erections in males (~38%), GI effects (nausea, diarrhea, abdominal pain); Skin hyperpigmentation: occurs in most patients due to MC1R agonism. Typically darkening of existing skin and nevi. Dermatologic monitoring recommended. |
| Route | Subcutaneous (clinical trial formulation only) | Subcutaneous injection |
| Dose Range | Phase 2 tested 1, 4, 8, 12 mg weekly SC; optimal dose being determined in Phase 3 | 1-3 mg once daily depending on age and response |
| Frequency | Once weekly | Once daily |
| Molecular Weight | N/A | ~1117.3 g/mol |
| Half-Life | ~6 days (allows once-weekly dosing) | ~11 hours |
Overview
Retatrutide and Setmelanotide are both research peptides studied across multiple applications. This comparison examines their mechanisms, evidence base, dosing protocols, and safety profiles to help researchers understand the key differences and overlaps.
Retatrutide — Mechanism & Evidence
Retatrutide is a first-in-class investigational triple hormone receptor agonist (GIP, GLP-1, and glucagon) developed by Eli Lilly. In the Phase 2 trial (Jastreboff et al., NEJM 2023, n=338), the 12 mg dose achieved 24.2% mean body weight reduction at 48 weeks, with 100% of participants achieving at least 5% weight loss. Multiple Phase 3 TRIUMPH trials are ongoing, with TRIUMPH-4 (Dec 2025) reporting average loss up to 71.2 lbs with osteoarthritis pain relief. Expected FDA approval is 2027-2028.
Key claims: Unprecedented weight loss in Phase 2; Phase 3 confirms efficacy with osteoarthritis benefit; Improves glycemic control in type 2 diabetes.
Setmelanotide — Mechanism & Evidence
Setmelanotide (brand name Imcivree) is a cyclic 8-amino-acid peptide (MW ~1117.3 g/mol) that acts as a melanocortin 4 receptor (MC4R) agonist. FDA-approved in November 2020 by Rhythm Pharmaceuticals, it is the first-ever treatment for chronic weight management in patients aged 6 years and older with monogenic or syndromic obesity due to POMC, PCSK1, or LEPR deficiency confirmed by genetic testing. It was subsequently approved for Bardet-Biedl syndrome (BBS) in June 2022. Setmelanotide directly restores MC4R signaling downstream of the defective leptin-melanocortin pathway.
Key claims: Significant weight loss in POMC deficiency obesity; Effective in LEPR deficiency obesity; Reduces hyperphagia in Bardet-Biedl syndrome.
Shared Research Applications
Both peptides are studied for: Weight Management, Metabolic Health.
Retatrutide is also researched for: no additional unique applications.
Setmelanotide is also researched for: no additional unique applications.
Safety Considerations
Retatrutide: GI side effects (dose-related, 13-63% across dose groups): nausea, vomiting, diarrhea, constipation; mostly mild to moderate GI events partially mitigated with lower starting dose (2 mg vs 4 mg initial dose) Dose-dependent heart rate increases peaking at 24 weeks, declining thereafter
Setmelanotide: Common (>=10%): injection site reactions (45%), skin hyperpigmentation (75%, due to MC1R activation), spontaneous penile erections in males (~38%), GI effects (nausea, diarrhea, abdominal pain) Skin hyperpigmentation: occurs in most patients due to MC1R agonism. Typically darkening of existing skin and nevi. Dermatologic monitoring recommended. Spontaneous erections and sexual adverse effects: common in males due to central melanocortin signaling. Generally decrease over time.
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Related Research News
Retatrutide Clinical Trial Results: Phase III TRIUMPH Data Shows Significant Weight Loss
Early reports from the Phase III TRIUMPH-1 trial suggest retatrutide, a novel triple agonist, has delivered substantial weight loss outcomes. These retatrutide clinical trial results indicate a potential shift in obesity treatment research, though full data analysis is pending.
Retatrutide Phase III TRIUMPH-1 Results: Unprecedented Weight Loss Reported at ADA26
Early reports from the American Diabetes Association 2026 meeting suggest retatrutide delivered unprecedented weight loss in the Phase III TRIUMPH-1 trial. Researchers and industry professionals are closely watching these retatrutide clinical trial results for implications in obesity and metabolic disease treatment.
Retatrutide Monthly Research Cost in Australia Breakdown
Researching Retatrutide (LY3437943), the most advanced triple GLP-1/GIP/glucagon receptor agonist, involves costs that vary by vial size, dose, and frequency. In Australia, a 10mg vial costs $129.99 AUD ($13.00/mg), while a 20mg vial is $199.99 AUD ($10.00/mg). Supplies like bacteriostatic water and needles add to monthly expenses, with planning around a 4-week reconstituted stability window essential to minimize waste.