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Compounds / IGF-1 LR3

IGF-1 LR3

Full name
Long R3 Insulin-like Growth Factor-1
Mechanism
Modified IGF-1 analogue with an Arg3 substitution and N-terminal extension that markedly reduces binding to IGF-binding proteins, prolonging activity. Potent anabolic/proliferative signalling via IGF-1R.
Half-life
~20-30 hours (extended vs native IGF-1)
Administration
subcutaneous/intramuscular (anecdotal, unvalidated)
Typical dosage*
low: research-defined · typical: no established safe human dose; anecdotal 20-50mcg unvalidated · high: unknown safe ceiling — hypoglycaemia risk
Researched for
muscle-growth research (cell culture; supplied for laboratory use)
Reported side effects
hypoglycaemia (potentially severe), theoretical: promotion of occult tumour growth, organ growth concerns with chronic use
Interactions
additive hypoglycaemia with insulin
Commonly combined
used in anabolic protocols (anecdotal, high-risk)
Scheduling
🇦🇺 AUNot ARTG-registered; research; WADA prohibited (S2)
🇺🇸 USNot FDA-approved; WADA prohibited
🇬🇧 UKNot licensed; WADA prohibited
Regulatory status
WADA-prohibited. No established human therapeutic use; significant hypoglycaemia and theoretical oncogenic risk.

*Doses are commonly-reported figures from public sources, not a recommendation. Educational only.

8studies
9faqs
growth-factorbody-compositionresearch-chemical

Studies (8)

YearTitle / venueSource
2025IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep
American journal of physiology. Endocrinology and metabolism · preclinical
PMID 39679943
2025Intranasal 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
Journal of Alzheimer's disease : JAD · preclinical
PMID 39610283
2023Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris
Applied microbiology and biotechnology · preclinical
PMID 37261455
2023Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets
Journal of developmental origins of health and disease · preclinical
PMID 37114757
2020Coronary vascular growth matches IGF-1-stimulated cardiac growth in fetal sheep
FASEB journal : official publication of the Federation of American Societies for Experimental Biology · preclinical
PMID 32573852
2010Detection of His-tagged Long-R³-IGF-I in a black market product
Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society · preclinical
PMID 20675162
1999Action of long(R3)-insulin-like growth factor-1 on protein metabolism in beef heifers
Domestic animal endocrinology · preclinical
PMID 10370861
1997The somatotropic axis in neonatal calves can be modulated by nutrition, growth hormone, and Long-R3-IGF-I
The American journal of physiology · preclinical
PMID 9252489

Questions (9)

What is IGF-1 LR3?

IGF-1 LR3 (Long R3 Insulin-like Growth Factor-1). Modified IGF-1 analogue with an Arg3 substitution and N-terminal extension that markedly reduces binding to IGF-binding proteins, prolonging activity. Potent anabolic/proliferative signalling via IGF-1R.

What is IGF-1 LR3 used for?

Commonly discussed uses: muscle-growth research (cell culture; supplied for laboratory use). The evidence base is largely preclinical (animal/in-vitro); published randomised human clinical trials are lacking or absent. Note: most uses are not approved indications.

How does IGF-1 LR3 work?

Mechanism: Modified IGF-1 analogue with an Arg3 substitution and N-terminal extension that markedly reduces binding to IGF-binding proteins, prolonging activity. Potent anabolic/proliferative signalling via IGF-1R.

Is IGF-1 LR3 safe?

Reported considerations: hypoglycaemia (potentially severe), theoretical: promotion of occult tumour growth, organ growth concerns with chronic use. The evidence base is largely preclinical (animal/in-vitro); published randomised human clinical trials are lacking or absent. WADA-prohibited. No established human therapeutic use; significant hypoglycaemia and theoretical oncogenic risk. This is not a safety endorsement; safety data for unapproved compounds is incomplete.

What is the typical dose of IGF-1 LR3?

Commonly cited ranges (educational reference, not a recommendation): low research-defined, typical no established safe human dose; anecdotal 20-50mcg unvalidated, high unknown safe ceiling — hypoglycaemia risk. Administration: subcutaneous/intramuscular (anecdotal, unvalidated). Half-life: ~20-30 hours (extended vs native IGF-1).

Is IGF-1 LR3 legal in Australia?

Australian status: Not ARTG-registered; research; WADA prohibited (S2). WADA-prohibited. No established human therapeutic use; significant hypoglycaemia and theoretical oncogenic risk. General regulatory context: most active peptides are Schedule 4 and require a prescription; import via the Personal Importation Scheme requires a valid Australian prescription for prescription-only goods.

How do you store IGF-1 LR3?

Reconstitution/storage reference: research-defined (acidic diluent typical); storage: refrigerated.

What is IGF-1 LR3 commonly stacked with?

Commonly discussed combinations (anecdotal for unapproved compounds): used in anabolic protocols (anecdotal, high-risk). Stacking increases interaction/safety uncertainty.