IGF-1 LR3 vs LL-37 (Cathelicidin)
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 →LL-37 (Cathelicidin)
LL-37 is the only human cathelicidin antimicrobial peptide. It plays crucial roles in innate immunity and has shown diverse biological activities including antimicrobial, immunomodulatory, and wound healing properties.
Full details →Side-by-Side Comparison
| Aspect | IGF-1 LR3 | LL-37 (Cathelicidin) |
|---|---|---|
| Dose Range | 20 mcg–100 mcg | 500 mcg–1.6 mg |
| Frequency | 1x daily | 1x daily |
| Cycle Length | 4–6 weeks | 2–4 weeks |
| Route | subcutaneous | topical |
| 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. | Disrupts bacterial membranes, neutralizes endotoxins, modulates immune cell function, and promotes wound healing. Has both direct antimicrobial and immunomodulatory effects. |
| Typical Dosage | Research protocols typically use 20-100mcg daily, often divided into multiple injections or administered bilaterally to target muscles. | Research protocols vary widely. Typical ranges: 50-200mcg administered subcutaneously 2-3 times weekly. Some protocols use higher doses for acute infections. |
| Administration | Intramuscular injection (site-specific growth) or subcutaneous for systemic effects. Often cycled 4-6 weeks on, equal time off. | Subcutaneous injection. Can cause significant injection site reactions. Often used in conjunction with other immune-supporting protocols. |
| Side Effects | Hypoglycemia, joint pain, water retention, potential jaw/hand growth with extended use, and injection site reactions. | Injection site pain and reactions are common. May cause flu-like symptoms, temporary fatigue, or immune activation responses. |
| Best For |
What They Have in Common
IGF-1 LR3, LL-37 (Cathelicidin) are both commonly used for:
Key Differences
Unique to IGF-1 LR3:
Which Has Stronger Evidence?
| Goal | IGF-1 LR3 | LL-37 (Cathelicidin) |
|---|---|---|
| Recovery & Healing | medium | medium |
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
LL-37 (Cathelicidin)
- Cathelicidin LL-37 Expression in Human Breast Implant Capsules.
Plastic and reconstructive surgery, 2024
- Salivary Cathelicidin (LL-37) in Children and Adolescents Living with HIV.
Biomedicine hub, 2024
- Antifungal properties of cathelicidin LL-37: current knowledge and future research directions.
World journal of microbiology & biotechnology, 2023
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