A modified, longer-acting analog of insulin-like growth factor 1 made primarily for cell-culture research.
Long R3 IGF-1 is an 83-amino-acid analog of IGF-1 with an arginine substitution at position 3 and a 13-amino-acid extension. Those changes reduce binding to IGF-binding proteins, so more of it stays active. It is manufactured mainly as a reagent for growing cells in laboratories.
IGF-1 LR3 is not approved for human use. IGF-1 and its analogs are prohibited in sport under WADA rules.
Status reflects public FDA actions and reporting as of October 8, 2026. An advisory committee vote is a recommendation, not an FDA decision, and inclusion on a compounding list is not FDA approval.
There are no controlled human studies of IGF-1 LR3. The only approved IGF-1 drug is mecasermin (Increlex), a recombinant form of natural IGF-1 for severe primary IGF-1 deficiency in children, given under specialist supervision.
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