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Peptides Muscle Building

IGF-1 LR3

Long R3 IGF-1 · LR3

Long-acting IGF-1 analog engineered to resist binding proteins; muscle-growth research compound.

Overview

IGF-1 LR3 (Long R3 IGF-1) is a modified analog of insulin-like growth factor 1, engineered with an arginine substitution at position 3 and an extended N-terminal. That modification sharply reduces binding to IGF-binding proteins, leaving more free, active hormone to stimulate the IGF-1 receptor and drive anabolic and muscle-growth signaling. Compared with native IGF-1, the LR3 variant is more potent and longer-acting. Its estimated half-life is roughly 12 hours with around 60% bioavailability, longer than the native peptide. The honest evidence picture is that human pharmacokinetic data is essentially absent and IGF-1 LR3 is not an approved medication. Most of what is known comes from in vitro potency work, animal studies, and the broader IGF-1 literature.

Pharmacokinetic summary

Model tier
Simple (t½ + F, Tmax estimated)
Half-life
0.5 days
Bioavailability
60%
Typical dose
0.02–0.1 mg

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