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No. 017 · GH & Growth · Growth Factor

IGF-1 LR3

Long R3 IGF-1LR3-IGF-1

C Tier C · Animal data how tiers work →
  • Not FDA approved
  • WADA ✗ S2
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Fingerprint no sequence
IGF-1 LR3 (no defined sequence)

No sequence on file. We only draw fingerprints from published sequences — this ring motif is a placeholder, never a guessed sequence.

01

Evidence

  1. D In vitro
  2. C Animal
  3. B Human pilot
  4. A RCT
  5. S Approved

TIER C — Evidence comes mostly from animal studies.

Used mainly as a cell-culture reagent and in animal studies; no human trials.

Tiers rate the strength of published evidence — not effectiveness, safety, or a recommendation.

02

At a glance

Routes studied
Subcutaneous, Intramuscular Routes used in published research
FDA
Not approved
WADA
Prohibited · S2 Peptide hormones, growth factors, related substances and mimetics
03

Overview

A potent long-acting analog of insulin-like growth factor 1 with an extended half-life due to an arginine substitution. It drives muscle hypertrophy and nutrient partitioning.

Research status Well-characterized growth factor biology; preclinical and limited human performance data

04

Mechanism

IGF-1 LR3 is a modified IGF-1 with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension, reducing IGFBP binding and extending its half-life from 12 minutes to 20-30 hours. It activates the IGF-1 receptor tyrosine kinase, stimulating the PI3K/Akt/mTOR pathway for protein synthesis and the Ras/MAPK pathway for cell proliferation.

05

Effects reported in research

Reported outcomes, not promises. These come mostly from preclinical (cell or animal) research and have not been confirmed in human trials.

  • Enhanced muscle protein synthesis
  • Improved nutrient partitioning toward muscle
  • Promoted hyperplasia (new muscle cell formation)
  • Increased nitrogen retention
06

Safety & unknowns

No formal human clinical trial data for therapeutic use. Potent growth factor with risks including hypoglycemia, organ growth, and theoretical cancer promotion via mTOR/proliferative signaling. Banned by WADA. Not FDA-approved. Requires careful glucose monitoring.

Unknowns. No randomized controlled trials in humans have been published, so human safety has not been established in controlled studies.

Informational only — not medical advice. peptidemeta publishes no dosing, protocols, or sourcing. Talk to a qualified clinician about any treatment decision.

07

Studies [1]

  1. Review 1995

    Insulin-like growth factors and their binding proteins: biological actions

    Jones JI, Clemmons DR. Endocrine Reviews

    Foundational review of IGF-1 biology, receptor signaling, and IGFBP interactions relevant to understanding the LR3 modification.

    [pubmed]

09

Status sources

Sources behind the tier, regulatory status, sequence and dates on this page.

10

Cite this entry

$ cite --format=apa

peptidemeta. (2026). IGF-1 LR3. In peptidemeta: The peptide library, ranked by evidence. Retrieved November 8, 2026, from https://peptidemeta.com/p/igf-1-lr3/

$ cite --format=bibtex 
@misc{peptidemeta-igf-1-lr3,
  title = {IGF-1 LR3},
  author = {{peptidemeta}},
  year = {2026},
  howpublished = {\url{https://peptidemeta.com/p/igf-1-lr3/}},
  note = {Accessed 2026-11-08}
}

Accessed date reflects when you opened this page. Cite primary studies for scientific claims.

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