IGF-1 LR3
IGF-1 Analog (long-acting)Also known as: Long R3 IGF-1 · Insulin-like Growth Factor-1 Long Arg3
A recombinant IGF-1 analog with an N-terminal arginine extension & Glu substitution at position 3 that reduces IGFBP binding & extends half-life to 20–30 hours.
Typical Dose
50–100 mcg/day, post-workout only
Route
Subcutaneous (near target muscle) or intramuscular
Cycle
4–6 weeks maximum; extended use suppresses endogenous IGF-1 production
Half-life
~20–30 hours
Storage
Lyophilized: 2–8°C. Reconstituted: 2–8°C, use within 14–21 days. Avoid room temp — degrades faster than most peptides.
Overview
IGF-1 LR3 is a modified version of Insulin-like Growth Factor-1 with a 13-amino-acid N-terminal extension (starting with arginine) & a glutamate substitution at position 3. These modifications reduce binding affinity for insulin-like growth factor binding proteins (IGFBPs), which normally sequester 97–99% of endogenous IGF-1. The result is a molecule with ~3x the biological activity of native IGF-1 & a half-life of 20–30 hours versus 12–15 hours for standard IGF-1.
IGF-1 LR3 drives protein synthesis, satellite cell activation, & hyperplasia in muscle tissue. Unlike GH secretagogues (which work by stimulating endogenous IGF-1 production), IGF-1 LR3 acts directly on IGF-1 receptors regardless of endogenous GH or IGF-1 status. It is used in contexts where direct, supraphysiological IGF-1 receptor activation is the goal.
Hypoglycemia is its most significant acute risk. IGF-1 receptors share significant homology with insulin receptors, & IGF-1 LR3 has measurable insulin-like activity that can cause dangerous blood glucose drops.
Quick Start Guide
Start with a test dose of 20 mcg to assess glucose response before full dosing.
Dose 50–100 mcg post-workout, injected near trained muscle (site-specific effect may enhance local muscle growth).
Have fast-acting carbohydrates immediately available. Monitor for hypoglycemia symptoms.
Do not dose pre-sleep; hypoglycemia while sleeping is dangerous.
Research Indications
Skeletal muscle hyperplasia & hypertrophy
EffectiveDirect IGF-1 receptor activation drives satellite cell proliferation (hyperplasia) & protein synthesis (hypertrophy). Particularly studied for site-specific muscle growth.
Post-workout recovery
EffectiveAcute dosing post-workout capitalizes on elevated muscle IGF-1 receptor sensitivity.
Research Protocols
Muscle building (advanced protocol)
4–6 weeks, then mandatory 4-week offDose
50–100 mcg post-workout
Frequency
Daily on training days; 4 days rest between cycles
Route
SubQ near target muscle
Never use pre-sleep. Consume 20–30g fast carbohydrate within 15 min of injection.
Peptide Interactions
Redundant mechanisms (both ultimately act via IGF-1 pathway) but synergistic if GH production is sub-optimal.
No adverse interaction. Sometimes stacked for combined recovery & muscle-building goals.
Side Effects & Safety
Common
- Hypoglycemia (most significant risk — have glucose available)
- Jaw pain, joint pain, or acromegaly-like symptoms at high doses
- Fatigue
- Headache
Uncommon
- Nausea
- Water retention
- Carpal tunnel syndrome
When to Stop
- Blood glucose below 3.5 mmol/L (63 mg/dL)
- Chest pain or cardiac arrhythmia
- Known or suspected malignancy
- Signs of allergic reaction
How to Reconstitute
Refrigerate & handle with care; IGF-1 LR3 is less stable than most peptides.
Add bacteriostatic water or 0.1% acetic acid slowly down the inner vial wall.
Swirl gently. Do not shake.
Use within 14–21 days. Do not freeze reconstituted solution.
Dosing math: Common: 1–2 mL BAC water per 1 mg vial = 500–1000 mcg/mL. For 100 mcg: 0.1–0.2 mL. Note: some users reconstitute in 0.1% acetic acid for improved stability; peptide is still active.
Quality Indicators
Good — use as normal
- Clear, colorless solution after gentle swirling
Acceptable
- Very slight opalescence that clears within 60 seconds
Discard immediately
- Persistent cloudiness
- Visible aggregation
- Warm or room-temp storage of reconstituted product for more than 24 hours
What to Expect
Days 1–3
Hypoglycemia risk is highest in the first few days as sensitivity establishes. Stay conservative with dose.
Week 1–2
Increased muscle fullness (glycogen & water driven by IGF-1 signaling). Recovery between sessions improves.
Week 3–6
Satellite cell proliferation accumulating. Muscle size & strength gains meaningful. Cease at 6 weeks to prevent downregulation.
Community Insights
Self-reported. Reflects user experience, not clinical outcomes.
Research References
The role of IGF-1 in muscle hypertrophy: what do we know?
Molecular Endocrinology · 2010
Review of IGF-1 signaling mechanisms in muscle including satellite cell activation & the specific advantages of LR3 modification over native IGF-1.
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Information on this page applies to pharmaceutical-grade peptides. Purity & identity of research-grade products vary. Certipep provides independent ESI-TOF-MS & HPLC analysis with a signed analytical report.
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