Explore IGF-1 LR3 dosage trends, reconstitution volumes, and vial size patterns from anonymized WPA peptide calculator sessions.
IGF-1 LR3 is a long-acting variant of insulin-like growth factor 1, engineered with an N-terminal extension that significantly extends its half-life versus native IGF-1. This data shows the dose amounts, vial sizes, and bacteriostatic water volumes researchers most commonly select when reconstituting IGF-1 LR3.
IGF-1 LR3 — Long Arg3 Insulin-like Growth Factor 1 — is one of the more interesting non-pharmaceutical molecules on this site, because it was never engineered as a human therapeutic. It was developed at GroPep Ltd in Adelaide, Australia in the late 1980s as a recombinant cell-culture reagent: the molecule is native human IGF-1 with a 13-amino-acid N-terminal extension and an arginine substitution at position 3, two engineering choices that together dramatically reduce binding to the IGF-binding proteins (IGFBPs) that normally tie up the vast majority of circulating IGF-1 in serum. The biological rationale is straight pharmacology: free IGF-1 is the bioactive fraction, IGFBP-3 alone binds about 75% of total IGF-1 in plasma, and an engineered variant that escapes IGFBP capture is more potent on a milligram-for-milligram basis and stays in circulation longer. The Tomas et al.
IGF-1 LR3 (Long Arg³ IGF-1) is an insulin-like-growth-factor analog most often sourced in bodybuilding and recomposition research; it was originally made as a cell-culture reagent, not a human therapy. It ships as a lyophilized powder you reconstitute with bacteriostatic water before use.
The Glu³→Arg substitution dramatically reduces affinity for the six IGF-binding proteins (IGFBPs) that normally sequester ~99% of circulating IGF-1, while the N-terminal extension preserves binding to the IGF-1 receptor. The combined effect is that IGF-1 LR3 retains roughly 30% of native IGF-1's receptor affinity but exhibits 2–3× greater in vivo bioactivity and a longer functional half-life because it is not buffered by IGFBPs.
IGF-1 LR3 is sold by major life-sciences suppliers (Sigma-Aldrich, Repligen, GroPep) as an animal-component-free supplement for CHO and hybridoma cell cultures used in biologics manufacturing. No clinical-trial sponsor has ever pursued human therapeutic development; the molecule is explicitly not intended for human use, and the World Anti-Doping Agency lists IGF-1 LR3 as a prohibited substance.
IGF-1 LR3 has a reported half-life of ~20–30 hours, and the dose intervals researchers model most often fall around once daily. Reduced IGF-binding-protein affinity gives LR3 a much longer half-life than native IGF-1, so daily dosing produces real day-to-day buildup over the first few days. It is catalogued under Muscle Peptides on WPA.
410 IGF-1 LR3 reconstitution calculations have been logged by the WPA community. The most common dose entered is 50mcg (136 calculations). The most common bacteriostatic water volume is 2mL. The most popular vial size is 1mg (335 sessions). The most common dosing frequency is daily (7x/week) (34 logged protocols), followed by 5x/week (16).
These figures come from anonymized WPA peptide calculator sessions.
All figures shown are aggregated from anonymized calculator inputs and are provided strictly for independent laboratory research and educational purposes. They are community usage statistics — not dosing recommendations, and not medical advice.