WhatPeptide

IGF-1 LR3

IGF-1 LR3 is a recombinant analog of insulin-like growth factor-1 engineered with an arginine substitution and 13 amino acid N-terminal extension to dramatically extend its plasma half-life and reduce IGF-binding protein affinity, enhancing its anabolic potency. It is studied for muscle hypertrophy, recovery acceleration, and tissue repair.

Moderate evidence Unregulated Growth Factor

Written by WhatPeptide Editorial Team · Last updated 2026-03-17

Half-life

Approximately 20-30 hours

Dosage range

20-100 mcg subcutaneously post-exercise (research context)

Administration

Subcutaneous injection

Research level

Moderate

How IGF-1 LR3 works

IGF-1 LR3 binds the IGF-1 receptor (IGF1R) and stimulates the PI3K/Akt/mTOR pathway to promote protein synthesis, amino acid uptake, and satellite cell activation in skeletal muscle. Its reduced affinity for IGF-binding proteins (IGFBPs) compared to native IGF-1 results in a greater fraction of bioavailable peptide and a half-life of approximately 20-30 hours versus minutes for recombinant IGF-1. Systemic administration presents risks including hypoglycemia and potential tumor promotion due to IGF1R's mitogenic signaling.

Also known as: Long-R3 IGF-1, Insulin-like Growth Factor-1 LR3, LR3-IGF-1

Research relevance

Muscle Growth
Strong research relevance 85
Recovery & Healing
Moderate relevance 60

Side effects & safety

Hypoglycemia Joint pain Edema Acromegalic features with prolonged use Potential tumor promotion

Contraindications

Active or prior malignancy
Diabetic retinopathy
Pregnancy
Acromegaly

Consult a healthcare provider before use if any of these apply to you.

Key studies

FAQ

What is IGF-1 LR3? +
IGF-1 LR3 is a recombinant analog of insulin-like growth factor-1 engineered with an arginine substitution and 13 amino acid N-terminal extension to dramatically extend its plasma half-life and reduce IGF-binding protein affinity, enhancing its anabolic potency. It is studied for muscle hypertrophy, recovery acceleration, and tissue repair. Its mechanism of action is supported by moderate clinical and preclinical evidence.
What is IGF-1 LR3 researched for? +
IGF-1 LR3 has the strongest research relevance for Muscle Growth, Recovery & Healing. Evidence is supported by moderate clinical and preclinical evidence.
What are the side effects of IGF-1 LR3? +
Reported side effects include Hypoglycemia, Joint pain, Edema, Acromegalic features with prolonged use, Potential tumor promotion. Key contraindications: Active or prior malignancy; Diabetic retinopathy; Pregnancy; Acromegaly.
Is IGF-1 LR3 FDA approved? +
IGF-1 LR3 is not FDA-approved. It is available as a research compound or through compounding pharmacies in some jurisdictions.
How is IGF-1 LR3 administered? +
IGF-1 LR3 is typically administered via subcutaneous route. Researched dosage range: 20-100 mcg subcutaneously post-exercise (research context). Half-life: Approximately 20-30 hours.

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