Overview

A laboratory reagent engineered to evade IGF-binding proteins so it stays active in cell culture. Applying that design to a human body removes the buffering system that normally keeps IGF-1 signalling controlled — which is exactly the point of concern.

Not approved for human use anywhereNo approval anywhere for human use. Sold under research-use labelling. Not approved for human use anywhere. Sold under research-use-only labelling.

At a glance

Regulatory status	Sold as a cell-culture research reagent. Never developed for human therapeutic use. WADA-prohibited.
Drug class	Modified insulin-like growth factor 1 analog with reduced binding-protein affinity
Route	Subcutaneous (research reagent)
Half-life	~20–30 hours (versus ~10 minutes for native free IGF-1)
Evidence rating	1/5 Minimal Evidence rating 1 out of 5: Minimal Animal or laboratory data only. No human efficacy evidence.
Studied in	Cell culture and animal research only. No human clinical trials of the LR3 analog exist.

How it works

Binds the IGF-1 receptor, driving PI3K/Akt and MAPK signalling: protein synthesis, satellite-cell activation, cell proliferation and survival. The R3 substitution and 13-residue N-terminal extension drastically reduce IGFBP binding, producing sustained unbuffered receptor activation.

Evidence base

Rated 1 of 5 — Minimal. Animal or laboratory data only. No human efficacy evidence.

Zero human clinical trials. Everything known comes from cell culture and animals.

Benefits & potential uses

Bars indicate how well each claim is supported: three = strong human evidence, two = moderate, one = preliminary or preclinical.

Potent anabolic signalling in vitro Preliminary

Reliably drives protein synthesis and cell proliferation in laboratory models — this is its intended purpose.
Native IGF-1 has approved uses Moderate evidence

Recombinant human IGF-1 (mecasermin) is approved for severe primary IGF-1 deficiency, establishing that the pathway is therapeutically tractable. LR3 is not that drug.

Risks, cons & cautions

Bars indicate seriousness: three = serious or common, two = moderate, one = minor.

Hypoglycemia Serious

IGF-1 has meaningful insulin-receptor cross-reactivity; severe hypoglycemia is the most common acute harm reported with IGF-1 analogs.
Cancer promotion concern Serious

Elevated IGF-1 signalling is epidemiologically associated with several cancers and is a core proliferative pathway. Unbuffered chronic elevation is the worst-case version of this exposure.
No human safety data whatsoever Serious

There is no dose that has been shown to be safe in people, because none has been studied.
Organ and tissue overgrowth Moderate evidence

Animal models show visceral organ growth with sustained IGF-1 elevation.
Reagent-grade manufacturing Serious

Products are labelled and manufactured for laboratory use, not for injection into humans.
WADA prohibited Minor

Banned at all times.

Who should avoid it

All human use — this is a laboratory reagent, not a medicine

If used under medical supervision, monitor

Not applicable

Interactions

Not exhaustive. Always have a pharmacist or physician review your full medication list — including supplements.

Insulin — additive and potentially severe hypoglycemia
Growth hormone and secretagogues — compound IGF-1 elevation
Corticosteroids — oppose the anabolic effect

Regulatory & legal status

Not approved for human use anywhere. Sold under research-use-only labelling.

Infographic

IGF-1 LR3 — benefits & risks at a glance Download SVG

Where to read further

We link to live literature searches rather than a frozen citation list, so you always see current results — including anything published after our last review.

IGF-1anabolicresearch reagenthigh risk

Related peptides in Growth Hormone Axis

Terms used on this page

Insulin-Like Growth Factor 1 (IGF-1): IGF-1 is a 70-amino-acid, proinsulin-like peptide produced mainly by the liver under growth hormone control, and it mediates most of the anabolic effects attributed to growth hormone.
N-Terminus: The N-terminus is the end of a peptide chain bearing a free alpha-amino group, the point from which sequences are written and from which aminopeptidases and DPP-4 begin degrading the molecule.
Off-Target Activity: Off-target activity is any interaction a compound has with proteins other than its intended target, and it is a matter of degree rather than a property a drug either has or lacks.
Hypoglycaemia: Hypoglycaemia is a plasma glucose concentration low enough to risk harm, graded in three consensus levels ending in severe events that require another person's assistance.
Peptide Analog: A peptide analog is a molecule built from a native peptide sequence with deliberate substitutions or chemical modifications intended to change its stability, duration or receptor profile.
Preclinical Study and Animal Model: Preclinical studies are the laboratory, cell and animal experiments done before any human exposure, establishing mechanism, target engagement and the toxicology package that permits a first trial.

This page is educational information, not medical advice. It cannot account for your medical history, medications, or risk factors. Do not start, stop or change any treatment based on it. Speak to a qualified healthcare professional who knows your case.