IGF-1 LR3

Quick Facts

• Full Name: Long R3 Insulin-Like Growth Factor-1
• Aliases: IGF-1 LR3, Long-R3-IGF-I
• Category: Muscle Building / Fat Loss / Recovery
• Molecular Weight: ~9117 Da (83-AA analogue)
• Administration: Subcutaneous (post-workout preferred)
• Typical Dose: 20–50 mcg/day SubQ post-workout
• Half-Life: ~20–30 hours (vs ~12–15 min for native IGF-1, due to reduced IGFBP binding)
• Cycling: 4–6 week cycles; extended use risks hypoglycemia and receptor desensitization
• Status: Research Only — higher risk profile than most peptides

What It Does

IGF-1 LR3 is a recombinant analogue of IGF-1 with an N-terminal extension (Arg3) and substitution that dramatically reduces its binding to IGF Binding Proteins (IGFBPs), extending its half-life 30-fold. This makes it significantly more potent and longer-acting than native IGF-1 — activating the IGF-1R across muscle, fat, and connective tissue simultaneously. It drives satellite cell activation, protein synthesis, and lipolysis, but with a significant hypoglycemia risk.

Mechanism of Action

1. IGF-1R agonism: Binds IGF-1 receptor → PI3K/Akt/mTOR → protein synthesis, satellite cell activation
2. Reduced IGFBP binding: Arg3 substitution + N-terminal extension → 30x longer half-life vs native IGF-1
3. Satellite cell activation: Stimulates muscle stem cell (satellite cell) proliferation and differentiation → muscle hyperplasia
4. Protein synthesis: Upregulates mTORC1, p70S6K, and 4E-BP1 → enhanced muscle protein synthesis
5. Lipolysis: IGF-1R activation in adipose tissue → fat oxidation
6. Insulin-like hypoglycemic effect: Activates IR (insulin receptor) at high doses → glucose uptake → hypoglycemia risk

Ageless Peps Products

• AP-IGF1LR3-Vial — IGF-1 LR3 Vial, $160, retail (draft status)

Dosing Protocols

Standard Protocol

• Dose: 20–50 mcg SubQ
• Timing: Post-workout (30–60 min after training; local injection near worked muscle for regional hypertrophy)
• Frequency: Daily or every other day
• Cycling: 4–6 weeks on; 6–8 weeks off (receptor desensitization prevention)

Conservative Start

• Dose: 20 mcg/day to assess glucose response
• Monitoring: Blood glucose monitoring recommended, especially initially

Stacks Well With

• CJC-1295 NO DAC + Ipamorelin – GH axis amplification of IGF-1 effects
• PEG-MGF – satellite cell activation + IGF-1 LR3 muscle growth stack
• BPC-157 – recovery + injury protection during anabolic cycle

Use Cases

• Muscle Building / Muscle hyperplasia
• Fat Loss / Body recomposition
• Recovery from injury or intense training
• Sarcopenia (investigational)

Contraindications & Safety

• Active malignancy (absolute) — IGF-1R drives tumor proliferation; significant risk
• Diabetic retinopathy — IGF-1 worsens retinal neovascularization
• Hypoglycemia risk — must have fast-acting carbohydrates available; monitor blood glucose
• Acromegaly features — jaw/hand/foot growth possible with chronic high-dose use
• Higher risk profile than other peptides in this database — use with caution
• Common: Hypoglycemia, injection site reactions, headache, water retention

Storage

• Lyophilized: -20°C for 1–2 years; avoid freeze-thaw cycles
• Reconstituted: 2–8°C; use within 2–3 weeks; use acetic acid for reconstitution (NOT bacteriostatic water)

PubMed Research

Studies

• PMID-36091374 – Sheep recombinant IGF-1 promotes organ-specific growth in fe | PubMed 36091374
  • Sheep recombinant IGF-1 promotes organ-specific growth in fetal sheep.
• PMID-33427051 – IGF-1 infusion to fetal sheep increases organ growth but not | PubMed 33427051
  • IGF-1 infusion to fetal sheep increases organ growth but not by stimulating nutrient transfer to the fetus.
• PMID-32573852 – Coronary vascular growth matches IGF-1-stimulated cardiac gr | PubMed 32573852
  • Coronary vascular growth matches IGF-1-stimulated cardiac growth in fetal sheep.
• PMID-41418663 – Provisional Treatment of Volumetric Muscle Loss With Insulin | PubMed 41418663
  • Provisional Treatment of Volumetric Muscle Loss With Insulin-like Growth Factor 1 Releasing Muscle Void Fillers.
• PMID-16166219 – The local expression and abundance of insulin-like growth fa | PubMed 16166219
  • The local expression and abundance of insulin-like growth factor (IGF) binding proteins in skeletal muscle are regulated by age and gender.

Sources

• The Peptides Bible
• Peptides Made Easy

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