What is IGF-1 LR3?
IGF-1 LR3 (Long R3 IGF-1) is a modified analog of insulin-like growth factor 1. Two changes distinguish it from native IGF-1:
- An arginine substitution at position 3 (R3)
- A 13-amino-acid N-terminal extension (the “Long” part)
Together these sharply reduce its binding to the IGF-binding proteins (IGFBPs) that normally sequester native IGF-1. The result is a far longer duration of action — native IGF-1 clears in roughly 10-20 minutes, whereas the reduced IGFBP binding of LR3 extends its activity substantially. It is one of the most-referenced compounds in muscle and tissue-growth research, searched as “Long R3” or “LR3”.
Important: This Peptide Does NOT Reconstitute With Bacteriostatic Water
Unlike most research peptides, IGF-1 LR3 is poorly soluble at neutral pH. It must be reconstituted with a mildly acidic solution — commonly 0.6% acetic acid or acidic (low-pH) bacteriostatic water — not plain bacteriostatic water, in which it will not fully dissolve. This is the single most important handling point for the compound.
Quick Reference
| Parameter | Value |
|---|---|
| Peptide Amount | 1mg |
| Reconstitution Solvent | 0.6% acetic acid (NOT plain BAC water) |
| Recommended Volume | 1mL |
| Resulting Concentration | 1mg/mL (1000mcg/mL) |
| Typical Research Dose | 20mcg - 50mcg |
| Frequency | Once daily |
Reconstitution Guide
Materials Needed
- IGF-1 LR3 1mg lyophilized vial
- 0.6% acetic acid (or acidic bacteriostatic water) — not plain BAC water
- Insulin syringes (U-100, 29-31 gauge)
- Alcohol swabs
- Sharps container
Step-by-Step Instructions
-
Prepare workspace — Clean environment, gather materials, thorough handwashing.
-
Clean vial stoppers — Wipe both vials with alcohol swabs. Allow complete drying.
-
Draw acetic acid solution — Draw 1mL of 0.6% acetic acid using a sterile syringe.
-
Add to peptide — Inject slowly down the inside wall of the vial. Do not spray directly onto the powder.
-
Dissolve — Allow several minutes for complete dissolution. Gentle swirl only — no shaking. The acidic solvent is what allows the peptide to go into solution.
-
Verify — Solution must be completely clear.
-
Label and store — Note reconstitution date and solvent. Refrigerate immediately.
Dosage Protocol
Concentration Calculations
With 1mg peptide in 1mL of 0.6% acetic acid:
- Concentration: 1mg/mL = 1000mcg/mL
- Per unit (U-100 syringe): 10mcg per unit
Common Dose Calculations
| Desired Dose | Draw Volume | Syringe Units |
|---|---|---|
| 20mcg | 0.02mL | 2 units |
| 30mcg | 0.03mL | 3 units |
| 40mcg | 0.04mL | 4 units |
| 50mcg | 0.05mL | 5 units |
Because doses are tiny (2-5 units), precision matters. A 1mg/mL concentration keeps the maths simple: every 10mcg is one unit on a U-100 syringe.
Research Considerations
Mechanism
IGF-1 LR3 acts on the IGF-1 receptor, driving the anabolic and cell-proliferative signalling associated with native IGF-1 — but with a much longer active window because it evades the binding proteins that would otherwise clear native IGF-1 quickly. This extended action is the entire point of the LR3 modification.
Comparison Within the IGF Family
| Compound | Key trait | Duration |
|---|---|---|
| IGF-1 LR3 | Reduced IGFBP binding, extended action | Long |
| IGF-1 DES | Truncated, potent, local | Short |
| MGF | Splice variant, local repair | Very short |
| PEG-MGF | Pegylated MGF | Extended |
For the full family breakdown, see our IGF-1 LR3 vs DES vs MGF comparison.
Storage Requirements
Lyophilized (Powder)
- Temperature: -20°C or colder
- Duration: 2+ years
- Conditions: Dry, dark, protected from moisture
Reconstituted
- Temperature: 2-8°C (refrigerated)
- Duration: 2-4 weeks
- Conditions: Protected from light, never freeze
Safety Considerations
Research Precautions
- IGF-1 LR3 is a research compound
- Not approved for any indication in any jurisdiction
- Research use only — not for human consumption
- Growth-factor signalling is potent; handle with appropriate care
- Limited long-term safety data available
Handling
- Use sterile technique for all preparations
- Handle the acetic-acid solvent according to standard laboratory practice
- Never reuse needles or syringes
- Proper sharps disposal
Sourcing for Research
Source from verified suppliers that provide third-party testing and certificates of analysis (COA) for each batch. Compare purity documentation, shipping conditions, and batch traceability before purchasing research materials.
Scientific References
- Research literature on Long R3 IGF-1 structure, reduced IGF-binding-protein affinity, and extended duration of action versus native IGF-1.
- Research literature on IGF-1 receptor signalling and anabolic/cell-proliferative effects.
Last updated: July 19, 2026
Disclaimer: This information is for educational and research purposes only. IGF-1 LR3 is a research compound and is not approved for any use. Research-grade peptides are not intended for human consumption. Always follow applicable laws and institutional guidelines.