IGF-1 LR3

A modified analog of human IGF-1 featuring an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. These modifications drastically reduce binding to IGF binding proteins (IGFBPs), resulting in a much longer effective half-life and greater bioavailability than native IGF-1. It is one of the most potent peptides for promoting skeletal muscle hypertrophy and hyperplasia.

• Binds IGF-1 receptor (IGF-1R) with similar affinity to native IGF-1 but with greatly reduced IGFBP binding
• Activates PI3K/Akt/mTOR cascade driving protein synthesis and cell growth
• Stimulates satellite cell proliferation and differentiation (hyperplasia)
• Activates MAPK/ERK pathway promoting cell survival and proliferation
• Cross-reacts with insulin receptor at high concentrations (hypoglycemia risk)

• Active or history of any malignancy (potent growth factor)
• Diabetes or hypoglycemia-prone conditions
• Pregnancy or breastfeeding
• Diabetic retinopathy
• Under 25 years of age (open growth plates risk)

Store at 2–8°C (36–46°F) for up to 3 months. For long-term storage, keep at -20°C (-4°F). Once reconstituted, refrigerate and use within 28 days. Very fragile — avoid agitation and repeated freeze-thaw.

Reconstitute with 0.6% acetic acid or bacteriostatic water. Acetic acid solution improves stability. Gently swirl — do not shake.

IGF-1 LR3 has been widely studied in cell culture and animal models, demonstrating potent anabolic effects. Studies show 2-3x greater potency than native IGF-1 in stimulating muscle protein synthesis due to reduced IGFBP sequestration. Research in livestock has shown significant increases in lean mass. While no formal clinical trials exist for the LR3 variant, native IGF-1 (mecasermin) is FDA-approved for growth failure, establishing the pathway's clinical validity.