IGF-1 LR3 is a synthetic analogue of insulin-like growth factor 1 with an extended half-life of approximately 20–30 hours. It has been studied in animal and in-vitro models for anabolic and metabolic effects. There are no human clinical trials for performance or longevity applications.
Evidence Status
IGF-1 LR3 has no human clinical trial data for performance or longevity applications. Native IGF-1 (mecasermin) is FDA-approved only for severe primary IGF-1 deficiency in children. IGF-1 LR3 specifically is not approved by any regulatory agency.
Doses Used in Research
Doses used in preclinical research and informal research community reports range from 20–100 mcg per day, administered subcutaneously or intramuscularly. These are not validated human doses. No established safe or effective human dose exists.
Extended Half-Life Mechanism
The arginine substitution at position 3 and N-terminal extension reduce binding to IGF-binding proteins (IGFBPs), extending the half-life compared to native IGF-1. This modification increases receptor exposure time but also extends any potential off-target effects.