Growth ⏱ Half-life: Approximately 20-30 hours due to reduced IGFBP binding. Preclinical

IGF-1 LR3

Insulin-like Growth Factor 1 Long R3

Updated March 15, 2026
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Evidence at a Glance

Regulatory statusPreclinical
Long-acting IGF-1 analog; preclinical only. Native IGF-1 (mecasermin/Increlex) is FDA-approved, but LR3 is not.
Human evidenceNone
Animal evidenceLimited

IGF-1 LR3 is a long-half-life IGF-1 analog studied only in cell and animal models; it has no human clinical trials and is sold strictly as a research chemical.

What the research does not support

  • It has no human clinical trials and is not approved for human use anywhere.
  • FDA-approved IGF-1 therapy (mecasermin/Increlex) is native IGF-1 for growth disorders, which is not the same molecule as LR3.
  • Muscle hypertrophy and anti-atrophy findings come from animal overexpression models, not human dosing studies.
  • It is a WADA-prohibited substance banned at all times in sport.
Half-Life
Approximately 20-30 hours due to reduced IGFBP binding.
Mol. Weight
9111.0 g/mol

What is IGF-1 LR3?

IGF-1 LR3 is a potent, long-acting analog of insulin-like growth factor 1 — the primary downstream mediator of growth hormone’s anabolic effects. Its structural modifications give it approximately 3x the potency of native IGF-1 with dramatically extended activity.

Research Applications

Muscle hyperplasia and hypertrophy, protein synthesis signaling, tissue regeneration, anti-catabolic research, and cell culture media supplementation.

Dosage Information (Research Use)

Research doses: 20-100 mcg/day subcutaneously. Used in cycles of 4-6 weeks. Extremely potent — precise dosing required. Research use only.

Reconstitution & Handling

Reconstitute with BAC water or 0.6% acetic acid solution. Handle carefully.

Half-Life & Pharmacokinetics

Approximately 20-30 hours due to reduced IGFBP binding.

Reported Observations in Literature

Hypoglycemia risk (IGF-1 has insulin-like glucose-lowering effects), joint pain, potential organ growth with chronic use. Requires careful research protocol design.

Key Research References

  • Francis GL, et al. “Insulin-like growth factor 1 analogs with reduced affinity for insulin-like growth factor binding proteins.” Biochemistry. 1992

How IGF-1 LR3 Works

IGF-1 LR3 is a modified form of IGF-1 with an arginine substitution at position 3 and a 13-amino acid N-terminal extension. These modifications dramatically reduce binding to IGF-binding proteins (IGFBPs), resulting in much higher bioavailability and a 20-30 hour half-life versus 12-15 minutes for native IGF-1. Activates the IGF-1 receptor to promote protein synthesis, muscle hyperplasia (new cell formation, not just hypertrophy), and anti-apoptotic signaling.

Research Findings

Uniquely promotes muscle hyperplasia (new muscle fiber creation) in addition to hypertrophy, distinguishing it from GH-based approaches. Potent compound requiring precise dosing in research protocols.

Dosage & Administration

Research doses: 20-100 mcg/day subcutaneously. Used in cycles of 4-6 weeks. Extremely potent — precise dosing required. Research use only.

Safety & Side Effects

Hypoglycemia risk (IGF-1 has insulin-like glucose-lowering effects), joint pain, potential organ growth with chronic use. Requires careful research protocol design.

Important: All safety information is derived from published research, primarily animal studies. No controlled human clinical trial data exists unless explicitly noted. This compound is sold for research purposes only.

Quick Facts

Sequence 83-amino acid analog of IGF-1 with Arg3 substitution and 13-aa N-terminal extension
Molecular Weight 9111.0 g/mol
Half-Life Approximately 20-30 hours due to reduced IGFBP binding.
Available Sizes 0.1mg, 1mg
Storage Lyophilized: -20°C. Reconstituted: 2-8°C, use within 21 days.

Key Research References

  • Francis GL, et al. "Insulin-like growth factor 1 analogs with reduced affinity for insulin-like growth factor binding proteins." Biochemistry. 1992

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