PeptideCompareIGF-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.
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.
Pharmacokinetics
Potency retained over time
Each line is one storage condition: it starts at 100% and falls as potency is lost. Above the dashed 80% line the material is considered reliable — hover for exact values.
⚠ Modelled per compound from molecular structure — chain length, cyclisation, oxidation- and deamidation-prone residues and light sensitivity. Indicative only, not lab-measured per batch.
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References
- The defining in vivo comparison: Long-R3-IGF-I, which binds IGF-binding proteins poorly and is cleared faster, was 1.5-2x more potent than native IGF-I for weight gain, organ growth and anti-catabolic effect when infused into normal and dexamethasone-treated rats. This is a rat study, not a human trial. Tomas FM, Lemmey AB, Read LC, Ballard FJ. J Endocrinol. 1996;150(1):77–84. DOIPubMed 8708565
- The larger anabolic response of the analogue over native IGF-I under glucocorticoid-induced muscle catabolism in rats. Together with the 1996 study this is the core preclinical basis for the potency framing; both are rodent work. Tomas FM, Knowles SE, Owens PC, et al. Biochem J. 1992;282(Pt 1):91–97. DOIPubMed 1371669PMC