IGF-1 LR3 dosage and protocol
Last reviewed Oct 7, 2026. Editorial policy
IGF-1 Long R3 is a modified form of Insulin-like Growth Factor-1 with a longer half-life (20-30 hours vs 15 minutes for standard IGF-1). It promotes muscle hyperplasia (new muscle cell formation), nitrogen retention, and fat metabolism. One of the most anabolic peptides studied — promotes actual new muscle fiber creation.
- Vial size: 1 mg
- Reconstitution: 3 mL bacteriostatic water
- Concentration: 0.33 mg/mL (333 mcg/mL)
- Administration: subcutaneous
Research areas
- Muscle Growth
- Hyperplasia
- Fat Loss
- Recovery
- Anti-Aging
Quick start
- Reconstitute: Add 3.0 mL bacteriostatic water → ~0.333 mg/mL (333 mcg/mL) concentration
- Typical daily range: 20–50 mcg once daily subcutaneously (gradual titration)
- Easy measuring: At 0.333 mg/mL, 1 unit = 0.01 mL ≈ 3.33 mcg on a U-100 syringe
- Storage: Lyophilized at −20°C; after reconstitution, refrigerate at 2–8°C and use within 30 days
Dosing protocol
| Phase | Dose | Frequency | Volume |
|---|---|---|---|
| Weeks 1–2 | 20 mcg | Once daily (SC) | 0.06 mL (6 units) |
| Weeks 3–4 | 40 mcg | Once daily (SC) | 0.12 mL (12 units) |
| Weeks 5–8 | 50 mcg | Once daily (SC) | 0.15 mL (15 units) |
How it works
IGF-1 LR3 (Long R3 IGF-1) is an engineered version of insulin-like growth factor 1 with a 13-amino-acid extension at the N-terminus and an arginine substituted at position 3. These changes greatly reduce binding to IGF-binding proteins, which normally hold most circulating IGF-1 inactive, so more of the peptide stays free and its effective half-life is much longer than native IGF-1. It activates the IGF-1 receptor, a tyrosine kinase that signals through PI3K/Akt/mTOR to stimulate protein synthesis and cell growth, and through MAPK to promote cell proliferation. IGF-1 LR3 was developed mainly as a cell-culture supplement and is widely used in biomanufacturing. In cell and animal studies, IGF-1 signaling promotes muscle protein synthesis, satellite cell proliferation and nutrient uptake. Claims that LR3 builds new muscle fibers (hyperplasia) in humans come from animal and in vitro biology rather than human trials. IGF-1 also has insulin-like effects and can lower blood glucose. There are no clinical trials of IGF-1 LR3 in humans. Native recombinant IGF-1 (mecasermin) is FDA-approved only for severe primary IGF-1 deficiency in children, and its labeling highlights hypoglycemia as a key risk. Human safety of LR3 is unknown.
Units chart for a 1 mg vial
| Water added | Strength | 1 unit = | 20 mcg | 40 mcg | 50 mcg |
|---|---|---|---|---|---|
| 1 mL | 1 mg/mL | 10 mcg | 2 units | 4 units | 5 units |
| 2 mL | 0.5 mg/mL | 5 mcg | 4 units | 8 units | 10 units |
| 3 mL | 0.33 mg/mL | 3.3 mcg | 6 units | 12 units | 15 units |
Units on a U-100 insulin syringe (100 units = 1 mL).
Pages for each vial size and water volume
Reconstitution steps
- Draw 3.0 mL bacteriostatic water with a sterile syringe
- Inject slowly down the vial wall to avoid foaming; do not shake
- Gently swirl or roll until the powder dissolves into a clear solution
- Label with reconstitution date and refrigerate at 2–8°C, protected from light; use within 30 days
Storage
Evidence: Common practice. What vendors and users usually do. No published stability testing supports a specific number.
- Powder or unopened: Sealed powder: freezer (about −20 °C) for long-term storage, refrigerator for weeks. Let the vial reach room temperature before opening.
- Mixed or in use: Refrigerator, 2–8 °C. Do not freeze and thaw repeatedly.
- Use within: no tested number
- Light: Keep it in the box or another dark container.
Most reconstituted peptides are kept in the refrigerator (2–8 °C) and used within about 28 days. That is a convention, not tested data: the 28 days comes from the USP <797> limit for opened multiple-dose containers, which is about sterility, not about whether the peptide stays intact.
Sources: Crestigen: Peptide storage and handling guide; USP General Chapter <797> Pharmaceutical Compounding: Sterile Preparations
Store lyophilized at −20°C for up to 12 months. After reconstitution, refrigerate at 2–8°C and use within 30 days. For longer storage, freeze aliquots at −20°C; never refreeze thawed vials.
Important notes
- Research use only
- Administer with or shortly after food to mitigate insulin-like hypoglycemia risk
- Cycle 8 weeks on, 4–8 weeks off to prevent receptor desensitization
- Most common: once daily SC in the morning or post-workout
- Keep fast-acting carbohydrates on hand during dose titration
Supplies
- Bacteriostatic water
- Insulin syringes (U-100)
- Alcohol swabs
- Sharps container
- Fast-acting carbohydrate source (glucose tablets or juice)