Peptide Academy · Growth

IGF-1 LR3

Also known as Long R3 Insulin-like Growth Factor

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Educational research summary, not medical advice. Many compounds here are not approved for human use. Talk to a licensed clinician before making any health decision.

The Peptide Academy is free to read. Members also get the research protocols for IGF-1 LR3, dose and vial tracking, and an AI Advisor with cited sources. Try it all free for 7 days, no card needed.

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What is IGF-1 LR3?

A modified IGF-1 with extended half-life and reduced binding-protein affinity, studied in muscle-wasting models.

How it works

The Arg3 substitution and 13-aa extension reduce IGFBP binding, leaving more free peptide to activate IGF-1 receptors and the mTOR anabolic pathway.

What it has been studied for

  • Muscle cell hyperplasia
  • Enhanced protein synthesis
  • Improved nutrient partitioning
  • Fat oxidation
  • Accelerated recovery

These are effects reported or investigated in research, much of it preclinical. They are not proven outcomes or health claims.

Published research

  • Cell and animal anabolism literature
  • No approved human use

Half-life

~20 hours (Long R3 analog extends vs native IGF-1 ~10 min)

Cautions

Hypoglycemia risk; theoretical concern with any proliferative condition. WADA-banned.

Side effects & fixes

Common side effects

  • —Water retention and joint aches
  • —Tingling or numbness in the hands (carpal-tunnel-like)
  • —Headache
  • —Changes in blood sugar — low blood sugar is a known risk with IGF-1 products; higher blood sugar with growth hormone
  • —Injection-site redness

Histamine reactions

Occasional injection-site redness or itching.

Common fixes

  • Lower the dose if swelling, joint pain or numbness appears.
  • IGF-1 products: always have food around the dose and know the signs of low blood sugar (shakiness, sweating, confusion).
  • Track fasting glucose if you can.
  • Rotate injection sites (abdomen, thighs, upper arms) and stay at least an inch from the last spot.
  • Let the alcohol swab dry fully, let the solution reach room temperature, and inject slowly with a fresh needle.

Stop and get help

  • Signs of low blood sugar that don't improve with sugar or food, or confusion.
  • Stop and get emergency help for swelling of the face, lips, tongue or throat, trouble breathing, widespread hives, chest pain or fainting.

Basis: Prescribing information (somatropin, mecasermin) and clinical studies. Educational only, not medical advice.

Medication concerns

From FDA prescribing information

  • Insulin and other diabetes medicines

    IGF-1 lowers blood sugar like insulin does; together they raise the risk of severe lows. Take it with a meal or snack, as the mecasermin label directs.

  • Alcohol and skipped meals

    Both make low blood sugar more likely.

  • Medicines cleared by liver CYP450 enzymes (seizure medicines, cyclosporine, sex hormones, corticosteroids)

    Growth hormone may change how fast these are cleared. Levels may need monitoring.

  • Everything else you take, including supplements

    Bring a full list of medicines and supplements to your pharmacist or clinician before starting.

Basis: FDA prescribing information for Increlex (mecasermin); research IGF-1 analogs are assumed to behave similarly. Educational only, not medical advice. Never stop or change a prescribed medicine without your prescriber.

Protocols & tracking are members-only

Members see the research protocols for IGF-1 LR3, plan schedules, track every dose and vial, and ask the AI Advisor questions with cited sources. Try every Researcher feature free for 7 days, no card needed.

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