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36Plate 36Reviewed 2026-04-27

IGF-1 LR3

IGF-1 Analogue

also known as Long R3 IGF-1, LR3-IGF-I, Long Arg3 IGF-1

Synthetic IGF-1 analogue with arginine substitution at position 3 and a 13-amino-acid N-terminal extension. Exhibits markedly reduced binding to IGF-binding proteins (IGFBPs), producing prolonged half-life and enhanced bioavailability compared to native IGF-1. Primarily studied in research contexts for anabolic, anti-apoptotic, and cell proliferation effects.

§ I

At a glance

Potency vs IGF-I
3–10×
Binding affinity
Low IGFBP
Status
Research
Route

Research only · SQ typical in animal models

§ II

Mechanism

Edit ↗

Primary target — IGF-1 receptor (IGF-1R) [mctavish-2009].

Pathway — IGF-1R → IRS-1 → PI3K/Akt → Cell proliferation, protein synthesis, anti-apoptosis [muhlbradt-2009].

Downstream effect — Enhanced cell proliferation, muscle anabolism, inhibition of apoptosis, increased telomerase activity.

Origin — Synthetic 83-AA analogue: 13-AA N-terminal extension + Arg substitution at position 3.

Feedback intact — No — exogenous IGF analogue bypasses GH-mediated regulation.

§ III

Dosage

Protocols described in the cited literature; not medical advice.

Edit ↗
ParameterValue
Research dose (animal models)Variable by protocol and speciesIn vivo murine atherosclerosis studies used sustained delivery.
In vitro typical concentration10–1000 ng/mL [thomas-2007]Dose-dependent effects on follicle growth and estradiol production.
Half-maximal stimulation0.6 nM LR3 vs 1.5 nM native IGF-1 [price-2004]2.5-fold greater potency in lung fibroblast proliferation.
Evidence basisAnimal / in vitro only
Human useNot FDA-approved; no published human trials
§ III · b

Reconstitution

A pure mass-to-volume utility. Enter what you have in the vial; the atlas computes the volume per dose. No prescription information.

Inputs
mg
mL
mcg
The calculator does pure mass-to-volume math. It does not recommend a dose. Refer to IGF-1 LR3's cited literature for protocol specifics.
Volumetric outputFig. C — reconstitution math
Volume per dose
0.100mL
≈ 10.0 units on a U-100 insulin syringe
Concentration
2500
mcg per mL
Doses per vial
20
at this dose
§ IV

Evidence

Edit ↗
Strength
35/100
animal mechanistic

Animal models only · No controlled human trials

OutcomeFinding
MechanismIGF-1R activation → lipolytic signaling; secondary to anabolic effects
Direct lipolytic evidenceMinimal — primarily anabolic/anti-apoptotic in literature
Atherosclerotic plaque effectsReduced stenosis and core size in ApoE-KO mice [von-2011]Plaque stabilization via vSMC phenotype modulation, not direct fat loss.
Human dataNone published
§ V

Adverse events

Severities follow the FDA / CTCAE convention.

Edit ↗
Hypoglycemia riskmoderate
Theoretical — IGF-1 analogues can lower blood glucose
Excessive cell proliferationsevere
Mitogenic signaling; theoretical tumor promotion risk
Telomerase activationsevere
2–10-fold increase in prostate cancer cells (PC-3, DU-145, LAPC-4) [wetterau-2003]
Oocyte degenerationmoderate
Increased oocyte degeneration at high doses (≥1000 ng/mL) in bovine follicles [thomas-2007]
Unregulated anabolismmoderate
Bypasses physiological GH/IGF-1 feedback; no pulsatility control
Unknown human safety profilesevere
No published human trials; safety data absent
Absolute contraindications
  • — Active malignancy or history of cancer
  • — Not approved for human use
Relative contraindications
  • — Diabetes or glucose intolerance
  • — Family history of cancer
§ VI

Administration

Edit ↗
  1. 01
    Research use only

    IGF-1 LR3 is not FDA-approved for human use. All administration data derives from animal or in vitro studies.

  2. 02
    Typical research route

    Subcutaneous or intraperitoneal injection in animal models. In vitro: added directly to culture medium at concentrations of 10–1000 ng/mL. [thomas-2007]

  3. 03
    Reconstitution (research)

    Lyophilised powder reconstituted in sterile water or buffered saline per manufacturer protocol. Store at 2–8 °C after reconstitution.

  4. 04
    Stability

    Enhanced stability vs native IGF-1 due to reduced IGFBP binding; exact half-life in vivo not fully characterized in humans.

§ VII

Synergies

Edit ↗
multi-pathway synergy
Deterministic 12-node hex coat-of-arms fingerprint for Igf 1lr3, generated from the slug hash. Decorative; the same slug always produces the same motif.+Deterministic 12-node hex coat-of-arms fingerprint for Ghrp 6, generated from the slug hash. Decorative; the same slug always produces the same motif.
IGF-1 LR3 + GHRP-6

GHRP-6 stimulates endogenous GH release, which drives hepatic IGF-1 synthesis. IGF-1 LR3 provides exogenous, IGFBP-resistant IGF signaling. Combining upstream GH stimulation with downstream IGF receptor activation creates a dual-pathway anabolic effect. However, this bypasses natural feedback and carries compounded mitogenic risk.

Primary benefit — Theoretical maximal anabolic signaling (GH + IGF axes)
multi-pathway synergy
Deterministic 12-node hex coat-of-arms fingerprint for Igf 1lr3, generated from the slug hash. Decorative; the same slug always produces the same motif.+Deterministic 12-node hex coat-of-arms fingerprint for Ipamorelin, generated from the slug hash. Decorative; the same slug always produces the same motif.
IGF-1 LR3 + Ipamorelin

Ipamorelin (selective GHRP) stimulates pulsatile GH release without cortisol/prolactin elevation. IGF-1 LR3 directly activates IGF-1R independent of GH. This stack targets both upstream (GH secretion) and downstream (IGF receptor) nodes but eliminates physiological feedback, raising safety concerns around unchecked proliferation.

Primary benefit — Dual-axis anabolic signaling (theoretical)
Appendix

Sources

17%

of 58 rendered claims carry a resolvable citation.

  1. [mctavish-2009]
    McTavish 2009 — Novel insulin-like growth factor-methotrexate covalent conjugate inhibits tumor growth in vivo at lower dosage than methotrexate alone.
    journal, 2009
    PubMed →
  2. [muhlbradt-2009]
    Muhlbradt 2009 — NKX3.1 activates expression of insulin-like growth factor binding protein-3 to mediate insulin-like growth factor-I signaling and cell proliferation.
    journal, 2009
    PubMed →
  3. [price-2004]
    Price 2004 — Regulation of insulin-like growth factor (IGF)-binding protein expression by growth factors and cytokines alters IGF-mediated proliferation of postnatal lung fibroblasts.
    journal, 2004
    PubMed →
  4. [thomas-2007]
    Thomas 2007 — Effects of IGF-I bioavailability on bovine preantral follicular development in vitro.
    journal, 2007
    PubMed →
  5. [von-2011]
    von 2011 — IGF-1 has plaque-stabilizing effects in atherosclerosis by altering vascular smooth muscle cell phenotype.
    journal, 2011
    PubMed →
  6. [wetterau-2003]
    Wetterau 2003 — Insulin-like growth factor I stimulates telomerase activity in prostate cancer cells.
    journal, 2003
    PubMed →
Plate composed 2026-04-27 · maturity human-reviewed · schema v1 · Contributors: peptidesdb-core · 48 fields uncited — open contributions
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