IGF-1 LR3

IGF-1 LR3 (Long R3 IGF-1) is a modified form of insulin-like growth factor-1 with significantly enhanced biological activity and extended half-life compared to native IGF-1. The modification includes an arginine substitution at position 3 and a 13-amino acid N-terminal extension peptide. These changes dramatically reduce binding to IGF binding proteins (IGFBPs), which normally sequester and inactivate circulating IGF-1. Research demonstrates IGF-1 LR3 has approximately three times the potency of native IGF-1 and a half-life of 20-30 hours compared to 12-15 hours for unmodified IGF-1. The peptide stimulates protein synthesis, promotes muscle hypertrophy, enhances nutrient partitioning toward muscle, and exhibits potent anabolic effects. Studies show IGF-1 LR3 can act systemically when administered, unlike locally-acting forms. The extended activity and enhanced potency make it popular in research settings examining IGF-1 biology and potential therapeutic applications for muscle wasting and growth deficiencies. However, increased potency also raises concerns about potential adverse effects including hypoglycemia.

No indexed clinical trials, pharmacokinetic, or safety data exist for IGF-1 LR3 in humans; information derives from in-vitro characterization and animal studies of IGF-1 analogs, plus extrapolation from native IGF-1. IGF-1 signaling is associated with hypoglycemia risk and theoretical cancer-growth concerns, and dosing used by consumers is unvalidated.

Recombinant analog of human IGF-1 engineered (arginine at position 3 plus a 13-amino-acid N-terminal extension) to reduce IGFBP binding, prolonging activity and increasing potency in vitro/animal studies. No approved dosing or route; administered by injection in research settings.