Growth Hormone FDA-approved medicine

IGF-1 LR3

Long R3 IGF-1 · Receptor-Grade IGF-1 · LR3 IGF-1

Evidence: Approved label. Example dose: finalize with a provider. Not a fact-check stamp.

20-50mcg – 40-50 mcg SubQ daily

IGF-1 LR3 (Long R3 Insulin-like Growth Factor 1) is a modified synthetic analog of human IGF-1 with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. These modifications dramatically reduce binding to IGF binding proteins (IGFBPs), resulting in a much longer biological half-life (20-30 hours) compared to native IGF-1 (12-15 minutes). This means IGF-1 LR3 remains active in the bloodstream far longer, producing more potent and sustained anabolic effects.

Quick Start

Route

Subcutaneous (SubQ)

Start low

20-50mcg SubQ

Frequency

daily

Timing

Administer with food or have carbohydrates available due to hypoglycemia risk

Post-workout injection at target muscle (IM). Pin alone. 4-6 week cycles max.

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Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first

Conservative start

20-50mcg · Subcutaneous (SubQ) · daily

conservative starter

20-50mcg

daily

Expert

Anabolic Cycle

40-50 mcg · SubQ · Daily

anecdotal · community

Long-R3 analog resists IGFBP binding for a ~20-30h systemic effect. Cycle 4-6 weeks due to receptor downregulation.

40-50 mcg

Daily

Reconstitution CalculatorU-100

Vial strength

BAC water

Vials in this mix

Syringe size

Target dose

050100u

Draw to

— units

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I will split this dose across more than one syringe

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How it works

Binds to IGF-1 receptors (IGF-1R) on muscle and other tissue cells, activating the PI3K/Akt/mTOR signaling pathway, which promotes protein synthesis, cell growth, and inhibits apoptosis (programmed cell death).

Reduced IGFBP binding allows IGF-1 LR3 to circulate freely and remain bioactive for 20-30 hours, compared to minutes for native IGF-1. This provides sustained receptor activation and enhanced anabolic signaling throughout the body.

Stimulates satellite cell activation and proliferation in skeletal muscle, promoting muscle hyperplasia (formation of new muscle fibers) in addition to the hypertrophy produced by standard anabolic stimuli.

What to expect

Early

Days 1–7

Days 1-7: Mild hypoglycemia possible after dosing. Muscle pumps may increase during training. No major visible changes yet.

Evidence

HumanNo published trials

AnimalPresent

In-vitroStrong

Each reference below was re-fetched from its PubMed record, and the quoted sentence was confirmed to appear in that abstract and to support the claim it sits under. Follow any of them to read the source.

Evidence boundary from the checked abstract: Female guinea pigs of 350 g body weight were continuously infused for 7 days with recombinant guinea pig IGF-I or -II (120 or 360 micrograms/day) or long R3 IGF-I (LR3IGF-I) (120 micrograms/day), an analogue which has much reduced affinities for IGF binding proteins.

Female guinea pigs of 350 g body weight were continuously infused for 7 days with recombinant guinea pig IGF-I or -II (120 or 360 micrograms/day) or long R3 IGF-I (LR3IGF-I) (120 micrograms/day), an analogue which has much reduced affinities for IGF binding proteins.

Long R3 insulin-like growth factor-I (IGF-I) infusion stimulates organ growth but reduces plasma IGF-I, IGF-II and IGF binding protein concentrations in the guinea pig. The Journal of endocrinology · 1995 · PMID 7561636

Evidence scope. This entry supports only the exact statement quoted from the live abstract; it does not independently verify OnePin's displayed dose, route, frequency, formulation, population, or broader mechanism.

Claims we could not support

No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.

Dose/route: 20-50mcg; Subcutaneous (SubQ); daily. No checked live PubMed abstract verified this exact displayed dose, route, and frequency for the same molecule/formulation and relevant population.

Primary safety claim: Hypoglycemia (low blood sugar) - most significant acute risk, can be severe. No checked live PubMed abstract directly verified this source-JSON safety claim at the displayed formulation, route, and regimen.

Pharmacokinetics

Illustrative plasma concentration · 4 d

Half-life

~20-30 hours

Peak · Tmax

~1-2 hours

SubQ/IM

Elimination

~4-6 days

Bioavailability

~100%

SubQ/IM

Duration of action

24-36 hours

Clearance

Hepatic and renal (reduced IGFBP binding extends clearance)

Storage. Store refrigerated at 2-8C. Reconstituted solution should be used within 28 days. Avoid freeze-thaw cycles. Use bacteriostatic water for reconstitution.

Regulatory status

Not approved for human use by the FDA or any regulatory agency. Research chemical only. Native IGF-1 (mecasermin/Increlex) is FDA-approved for severe primary IGF-1 deficiency in children.

Put it to work

Calculate, log & track

Open IGF-1 LR3 straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.

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Go deeper

The guide & community

The complete IGF-1 LR3 walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.

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