IGF-1 LR3
Last reviewed
Also known as: Insulin-like Growth Factor 1 Long R3
IGF-1 LR3 is a long-acting analog of Insulin-like Growth Factor 1 studied for its ability to trigger new muscle cell creation (hyperplasia) beyond what training alone can achieve.
IGF-1 analog with extended half-life for muscle cell hyperplasia (new cell creation, not just hypertrophy). Promotes nitrogen retention and protein synthesis.
⚠️ Educational only · Not medical advice · Consult a doctor · Most peptides are research-only / not FDA-approved for human use
§ AI Reference Summary
IGF-1 LR3 (also known as Insulin-like Growth Factor 1 Long R3) is a prominently researched experimental compound classified strictly within the Growth Factor framework. Operating primarily through advanced pharmacological pathways, its core mechanism of action is as follows: it iGF-1 analog with extended half-life for muscle cell hyperplasia (new cell creation, not just hypertrophy). Promotes nitrogen retention and protein synthesis. with a documented biological half-life of roughly 20 hours, In preclinical investigative trials and independent academic studies, researchers utilizing IGF-1 LR3 have documented significant, quantifiable biological outcomes, primarily focusing on muscle growth, recovery, hyperplasia. Typical research protocols investigate administering 50 to 50mcg via subq pathways 5x/wk. However, it is critically important to understand that while IGF-1 LR3 demonstrates profound physiological potential in highly controlled laboratory settings, it remains classified strictly as a research chemical and has not been approved by the United States Food and Drug Administration (FDA) for human therapeutic, diagnostic, or dietary consumption. Independent chemical analysis via rigorous third-party Certificate of Analysis (COA) testing utilizing High-Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS) remains the industry gold standard for verifying its base elemental stability when reconstituted appropriately in sterile bacteriostatic water.
§ Mechanism of Action
IGF-1 analog with extended half-life for muscle cell hyperplasia (new cell creation, not just hypertrophy). Promotes nitrogen retention and protein synthesis.
§ Primary Benefits
- 1Muscle growth
- 2recovery
- 3hyperplasia
§ Clinical Evidence
IGF-1 LR3 promotes muscle growth in animal models
IGF-1 LR3 demonstrates significantly enhanced potency over native IGF-1 due to reduced binding protein affinity and extended half-life, promoting dose-dependent muscle growth.
PreclinicalIGF-1 signaling: muscle repair and regeneration review
Philippou & Barton (Growth Hormone & IGF Res.): Comprehensive review of IGF-1's role in muscle satellite cell activation, myoblast proliferation, and skeletal muscle regeneration.
PreclinicalIGF-1 and cancer risk comprehensive epidemiological review
Bowers et al.: Meta-analysis of epidemiological studies examining positive correlation between circulating IGF-1 levels and prostate, breast, and colorectal cancer risk.
Moderate-StrongRevolutionary decellularized Alstroemeria stem-based nerve conduit integrated with GelMA and controlled IGF-1 LR3 release for enhanced rat sciatic nerve regeneration.
A 2025 study found that a novel plant-based nerve conduit featuring controlled release of IGF-1 LR3 significantly improved axonal regeneration in a rat model of sciatic nerve injury. The conduit demonstrated performance comparable to autologous nerve grafts without inducing systemic toxicity.
PreclinicalIGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep.
A 2025 study found that a one-week infusion of IGF-1 LR3 did not improve growth or insulin secretion in growth-restricted fetal sheep. However, the treatment demonstrated a reduction in circulating amino acids, suggesting increased amino acid utilization.
PreclinicalIntranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice.
A 2025 study found that intranasal LR3-IGF-1 promoted amyloid plaque remodeling and reduced low molecular weight Aβ oligomers in the cerebral cortex of an Alzheimer's mouse model. However, the treatment failed to preserve cognitive function or memory in the mice.
PreclinicalChromatographic-mass spectrometric analysis of peptidic analytes (2-10 kDa) in doping control urine samples.
A 2024 study demonstrated a simplified, validated chromatographic-mass spectrometric method for efficiently extracting and detecting prohibited peptides, including insulins and GHRHs, in doping control urine samples. The approach successfully met World Anti-Doping Agency requirements and was verified using authentic post-administration samples.
PreclinicalInsulin-Like Growth Factor1 Preserves Gastric Pacemaker Cells and Motor Function in Aging via ERK1/2 Activation.
A 2023 study found that an IGF1 analog mitigated age-related loss of gastric pacemaker cells in mice by activating ERK1/2 signaling. This preservation demonstrated improved gastric compliance, increased food intake, and prevented impaired body weight gain in the animal model.
PreclinicalRecombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris.
In a 2023 study, researchers demonstrated that high levels of bioactive human IGF-1 and its analog LR3 IGF-1 can be successfully produced in a Pichia pastoris expression system by fusing them with xylanase. The purified recombinant proteins exhibited excellent cell proliferation bioactivity comparable to standard IGF-1.
PreclinicalAttenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets.
A 2023 study demonstrated that acute IGF-1 LR3 infusion in fetal sheep suppressed in vivo glucose-stimulated insulin secretion. However, researchers found that isolated islets retained the ability to recover insulin secretion in vitro, indicating beta-cells can overcome acute suppression.
Preclinical§ Safety Profile
Potent; use caution. Risk of hypoglycemia. Theoretical cancer promotion concern well-documented in literature. Research-only.
See our evidence grading methodology for how we evaluate and grade peptide safety data.
§ Dosing Protocol
⚠️ For educational purposes only. Not medical advice. Consult a healthcare professional before using any peptide.
RouteSubQ
Dose Range50–50 mcg
Frequency5x/wk
TimingPost-workout
Cycle Length4–4 weeks
BAC Water2.5 ml / 1mg vial
Very low doses. Inject post-workout for localized muscle effects. Monitor blood sugar closely. Short cycles only.
§ Pharmacokinetics
⏱️ Half-Life: 20h
Plasma concentration over time§ Regulatory
🇺🇸USA
Research Only🇨🇦Canada
Research Only🇬🇧UK
Unregulated🇪🇺EU
Unregulated🇦🇺Australia
Research OnlyLast updated: 2026-01 · Laws change frequently. Verify current status in your jurisdiction.
§ Expected Outcomes
Week 1
Enhanced nutrient partitioning; increased post-workout pumps
Weeks 2–4
Lean mass and recovery improvements; possible hypoglycemia if undereating
Month 2–3
Significant body composition changes; hyperplasia (new cell creation) possible
Long-term
Theoretical cancer promotion risk with chronic use; short cycles essential
§ Adverse Effects
| Side Effect | Incidence | Severity |
|---|---|---|
Hypoglycemia Especially if dosed without food nearby; have glucose on hand | ~10% of users | moderate |
Joint pain | ~8% of users | mild |
Headache | ~5% of users | mild |
Fluid retention | ~10% of users | mild |
Where to Source IGF-1 LR3 for Research
Finding verified, high-purity IGF-1 LR3 requires rigorous COA verification. We independently evaluate vendors based on third-party HPLC testing, purity thresholds (≥98%), and batch-specific documentation.
View COA-Verified IGF-1 LR3✓ Third-party tested·✓ US shipping·✓ COA on every batch
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§ About the Author
Dr. E. Vance
Editorial Director, PeptiDex
Dr. E. Vance is the Editorial Director at PeptiDex and leads the platform's editorial division, ensuring that every published research summary meets rigorous preclinical citation standards. With a Ph.D. in Molecular Pharmacology from Columbia Univers...
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⚠ Educational only · Not medical advice · Most peptides are research-only / not FDA-approved