IGF-1 LR3

IGF-1 LR3 is a synthetic, longer-acting analog of insulin-like growth factor 1 (IGF-1).

IGF-1 LR3 is engineered to carry growth signals from the liver to muscle, bone, and other tissues for a much longer period of time without being captured by proteins that limit IGF-1 activity. Structural changes in the peptide reduce its affinity for IGF binding proteins and extend its half-life to roughly 20-30 hours. [Source: Peptide Dosing Protocols]

IGF-1 LR3 is a synthetic, longer-acting analog of insulin-like growth factor 1 (IGF-1). The body's own IGF-1 carries growth signals from the liver to muscle, bone, and other tissues. IGF-1 LR3 is engineered to do the same thing, but for a much longer period of time and without being captured by the proteins that normally limit IGF-1 activity.

Two structural changes drive the difference. The peptide has an arginine in place of glutamic acid at position 3, and an extra 13-amino-acid extension on the front (the N-terminus), making the full chain 83 amino acids instead of native IGF-1's 70. These modifications cut its affinity for IGF binding proteins and stretch the half-life to roughly 20-30 hours.

There is no oral or topical version of IGF-1 LR3 in research use. The only practical research format is a lyophilized (freeze-dried) powder reconstituted with bacteriostatic water and injected subcutaneously or intramuscularly. This page treats injection as the only route.

IGF-1 LR3 dosing is reported in micrograms (mcg), not milligrams. Doses are small, so syringe accuracy matters. Community protocols generally cluster between 20 and 100 mcg per day, given as one daily injection because of the long half-life. None of these ranges come from a published human clinical trial of IGF-1 LR3 — they are extrapolated from preclinical work, the Increlex (mecasermin) clinical record, and decades of community reporting.

The pattern is consistent: strong mechanistic plausibility from preclinical data and adjacent human safety, no direct human efficacy or long-term safety data on IGF-1 LR3 itself. Any claim about expected human results in performance contexts goes beyond the published evidence. [Source: Peptide Dosing Protocols]

Provider notes: [PDP compound] igf-1-lr3