IGF-1 LR3
Long R3 Insulin-like Growth Factor-1
Mechanism of Action
Recombinant IGF-1 analog with a Glu3→Arg3 substitution and an added 13-residue N-terminal extension. These modifications sharply reduce affinity for IGF-binding proteins (IGFBPs) while retaining near-native affinity for the IGF-1 receptor, so a much larger fraction of the injected peptide stays free and bioactive — producing far greater potency per mole than native IGF-1 in cell and tissue models.
Key Benefits
- Potentiated IGF-1 receptor signaling vs native IGF-1 (in vitro)
- Muscle fiber hyperplasia and hypertrophy (preclinical extrapolation)
- Enhanced nutrient partitioning
- Accelerated recovery from training
Dosing Protocol
Cited papers prove the mechanism (reduced IGFBP binding → higher potency) in granulosa cells, chondrocytes, and macrophage precursors, not in human muscle-hyperplasia trials — "muscle fiber hyperplasia" above is a preclinical extrapolation, not a demonstrated human outcome. Because IGFBP affinity normally buffers IGF-1 activity, reduced binding means hypoglycemia risk is more pronounced and less self-limiting — monitor blood glucose closely and keep cycles short.
Ideal Candidates
Advanced users pursuing muscle hyperplasia research; requires blood glucose monitoring.
Side Effects & Safety
Hypoglycemia (insulin-like effect), organ/tissue overgrowth risk with prolonged use, injection site reactions, theoretical increased cancer risk via sustained growth-factor signaling.
Regulatory Status
RestrictedResearch compound only. No 503A bulks list. Theoretical oncogenic and hypoglycemic risk from sustained IGF-1R activation — limited human safety data.
Evidence & Citations
- Grimes RW, Hammond JM. Insulin and insulin-like growth factors (IGFs) stimulate production of IGF-binding proteins by ovarian granulosa cells. Endocrinology. 1992;131(2):553-8.
- Koedam JA, Hoogerbrugge CM, Van Buul-Offers SC. Differential regulation of IGF-binding proteins in rabbit costal chondrocytes by IGF-I and dexamethasone. J Endocrinol. 2000;165(3):557-67.
- Long E, Huynh HT, Zhao X. Involvement of insulin-like growth factor-1 and its binding proteins in proliferation and differentiation of murine bone marrow-derived macrophage precursors. Endocrine. 1998;9(2):185-92.
Frequently asked
What is IGF-1 LR3?+
IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1) is a peptide studied for igf-1 analog and extended bioactivity. Recombinant IGF-1 analog with a Glu3→Arg3 substitution and an added 13-residue N-terminal extension. These modifications sharply reduce affinity for IGF-binding proteins (IGFBPs) while retaining near-native affinity for the IGF-1 receptor, so a much larger fraction of the injected peptide stays free and bioactive — producing far greater potency per mole than native IGF-1 in cell and tissue models.
What is the dosing protocol for IGF-1 LR3?+
Literature commonly references 20 mcg/day (low) to 50 mcg/day (maintenance) via SubQ, on a 4–6 weeks cycle. Educational reference only — a licensed Stackhaus Health provider sets any personalized protocol.
What is the regulatory status of IGF-1 LR3?+
Research compound only. No 503A bulks list. Theoretical oncogenic and hypoglycemic risk from sustained IGF-1R activation — limited human safety data.
Where can I access IGF-1 LR3?+
Research-grade IGF-1 LR3 is available through Stackhaus Research. For a personalized, provider-reviewed protocol, consult a licensed clinician through Stackhaus Health.
More in Muscle & Performance
Used in these stacks
IGF-1 LR3 appears in 1 research protocol in the Stackhaus Academy library.