IGF-1 LR3 is a synthetic analog of human insulin-like growth factor-1 engineered with an N-terminal extension (13 amino acids) and a glutamic acid substitution at position 3, resulting in significantly reduced binding affinity to IGF binding proteins[1]. This modification extends the peptide’s half-life from minutes (native IGF-1) to several hours and enhances systemic bioavailability[2]. The extended circulation time allows for once-daily administration protocols in research settings. Unlike native IGF-1, which requires frequent dosing, IGF-1 LR3 maintains more stable plasma levels throughout the day[11]. The peptide exhibits anabolic and metabolic activities through IGF-1 receptor binding, though it has never been approved for therapeutic human use and remains confined to research applications[12]. Studies examining IGF-1 and its analogs demonstrate effects on cellular growth, protein synthesis, and metabolic regulation. The insulin-like properties of IGF-1 LR3 necessitate careful attention to blood glucose management, particularly during initial dosing and titration phases[6].
