IGF-1 LR3 vs Setmelanotide
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
IGF-1 LR3
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a modified version of IGF-1 with extended half-life and enhanced potency. The modifications prevent binding to IGF binding proteins, increasing bioavailability.
Full details →Setmelanotide
Setmelanotide (Imcivree) is an FDA-approved MC4R agonist for chronic weight management in patients with obesity due to specific genetic conditions (POMC, PCSK1, or LEPR deficiency).
Full details →Side-by-Side Comparison
| Aspect | IGF-1 LR3 | Setmelanotide |
|---|---|---|
| Dose Range | 20 mcg–100 mcg | 1 mg–3 mg |
| Frequency | 1x daily | 1x daily |
| Cycle Length | 4–6 weeks | 12–52 weeks |
| Route | subcutaneous | subcutaneous |
| Mechanism | Binds to IGF-1 receptors to promote protein synthesis, muscle growth, and fat metabolism. The LR3 modification (13 amino acid extension and arginine substitution) extends half-life from minutes to 20-30 hours. | Selective agonist of melanocortin 4 receptors (MC4R) in the hypothalamus, restoring the satiety signaling pathway that is disrupted in certain genetic obesity syndromes. |
| Typical Dosage | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. | Adults: Start 2mg daily, titrate based on tolerability up to 3mg daily. Pediatrics (6+): Weight-based dosing starting at 1mg daily. |
| Administration | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. | Subcutaneous injection once daily. Requires genetic testing to confirm eligible mutations before prescribing. |
| Side Effects | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. | Injection site reactions, skin hyperpigmentation, spontaneous penile erections, depression, and suicidal ideation (boxed warning). GI effects less common than GLP-1s. |
| Best For |
What They Have in Common
IGF-1 LR3, Setmelanotide are both commonly used for:
Key Differences
Unique to IGF-1 LR3:
Which Has Stronger Evidence?
- Fat Loss: Setmelanotide has stronger research support.
| Goal | IGF-1 LR3 | Setmelanotide |
|---|---|---|
| Fat Loss | medium | high |
Key Studies
IGF-1 LR3
- IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.
American journal of physiology. Endocrinology and metabolism, 2025
- Revolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration.
International journal of biological macromolecules, 2025
- Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets.
Journal of developmental origins of health and disease, 2023
Setmelanotide
- Setmelanotide in Bardet-Biedl Syndrome: A 52-Week Comparison of Phase 3 Trial Participants With a Matched Registry Cohort.
Obesity (Silver Spring, Md.), 2026
- Setmelanotide for the Treatment of Acquired Hypothalamic Obesity.
The New England journal of medicine, 2026
- Impact of the Melanocortin-4 Receptor Agonist Setmelanotide on MASLD and Kidney Function in Bardet-Biedl Syndrome.
The Journal of clinical endocrinology and metabolism, 2026
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