Peptide library
Your guide to this compound.
The long-R3 analogue differs from native IGF-I and licensed mecasermin. Reduced binding-protein affinity does not by itself establish a human half-life, superior results or safety.
Existing source snapshot critically reassessed.
Based on the selected source scope described in this profile, often an indexed abstract. Full methods and clinician sign-off remain pending; no systematic-review claim.
Editorial assessment · 2026-09-07
Source 1 · pubmed.ncbi.nlm.nih.gov
Source 2 · pubmed.ncbi.nlm.nih.gov
Laboratory systems and rats; human tissue assays are not human dosing trials.
Experimental activity varies with binding proteins and the model. This does not establish clinical physique, recovery or site-specific growth benefits.
US: the cited INCRELEX label concerns mecasermin, not this modified IGF-1. Its authorization cannot be assigned to this derivative. A complete derivative-specific jurisdictional review remains outstanding.
Selected abstracts and a related medicine label reviewed. No derivative-matched human dosing, efficacy, PK, long-term safety or stability was verified; this is not an exhaustive clinical review.
Modified IGF-1 with reduced binding-protein affinity; longer human exposure is not established by that property.
A 1992 study found that LR3 activity depended on the cell system and its IGF-binding proteins. In cells without detectable secreted binding proteins, LR3 was less potent than IGF-1. Reduced binding is not equivalent to universal superiority.
IGFBP context; no universal potency multiplier.
The catalog primarily cites laboratory or animal research. Human benefit, a safe dose and long-term risks cannot be inferred from those findings.
Related mecasermin risks support precaution only; not derivative-specific rates.
The catalog primarily cites laboratory or animal research. Human benefit, a safe dose and long-term risks cannot be inferred from those findings.
Source 1 · pubmed.ncbi.nlm.nih.gov
Source 2 · pubmed.ncbi.nlm.nih.gov
IGF-1 LR3 is a modified IGF-1 research protein with a 13-residue N-terminal extension and an arginine replacing glutamate at position 3 of the IGF-1 sequence. It is structurally distinct from intact IGF-1 and DES.
NMR construct identity, not product authentication.
A 1992 study found that LR3 activity depended on the cell system and its IGF-binding proteins. In cells without detectable secreted binding proteins, LR3 was less potent than IGF-1. Reduced binding is not equivalent to universal superiority.
IGFBP context; no universal potency multiplier.
No matched human LR3 elimination half-life was verified. In a rat renal-failure model, LR3 clearance increased. Reduced binding-protein affinity alone does not establish the inherited 20–30 hour human claim.
Rat disease model; human half-life remains unknown.
The related mecasermin medicine label warns about severe hypoglycemia and neoplasia. This supports caution about IGF-pathway effects, but does not supply adverse-event rates for this derivative.
Related mecasermin risks support precaution only; not derivative-specific rates.
Laajoki LG, Le Breton E, Shooter GK, Wallace JC, Francis GL, Carver JA, Keniry MA. Secondary structure determination of 15N-labelled human Long-[Arg-3]-insulin-like growth factor 1 by multidimensional NMR spectroscopy. 1997.
PMID: 9450557
Francis GL, Ross M, Ballard FJ, Milner SJ, Senn C, McNeil KA, Wallace JC, King R, Wells JR. Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency. 1992.
PMID: 1378742
Gillespie CM, Hazel SJ, Walton PE, Martin AA. Effects of chronic renal failure on plasma clearance of insulin-like growth factor I, des-(1-3)IGF-I, and LR3IGF-I. 1996.
PMID: 8897852
DailyMed. INCRELEX (mecasermin), US prescribing information, revised October 2025. Related medicine only; not an LR3 or DES label. Checked September 7, 2026.
Catalog review date: Sep 7, 2026. This date alone does not establish independent clinical review.