MONOGRAPH No. 072
💪 Muscle, IGF & Body Composition
IGF-1 LR3 — long-acting growth factor.
IGF-1 LR3 (Long R3 IGF-1) is a 83-amino acid analogue of Insulin-like Growth Factor 1 with an N-terminal extension and substitution that dramatically extends its half-life and reduces IGFBP binding — making it far more potent and longer-lasting than native IGF-1.
Last reviewed:
IGF-1 vs IGF-1 LR3 — the key differences
Native IGF-1 has a half-life of approximately 6 hours and binds tightly to IGF-binding proteins (IGFBPs) which reduce its bioavailability. IGF-1 LR3 has an arginine substitution at position 3 and a 13-amino acid extension at the N-terminus. These changes reduce IGFBP binding by ~1000x and extend half-life to ~20 hours. The result is significantly higher and more sustained bioavailability in research models.
⚠ Cold chain is essential. IGF-1 LR3 is one of the most temperature-sensitive peptides. Lyophilized powder requires refrigeration. Reconstituted solution should be used promptly and stored at 2-8°C. Always verify that your EU vendor ships with cold packs and confirm the product was stored correctly.
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