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IGF-1 LR3
The burned-in captions and transcript carry the scientific claims and their limitations. The visuals are conceptual illustrations, not validated molecular models or experimental images. The video has no voice or audio. The full explanation is visible on screen; optional accessible captions are available in the player.
Read every result in its study context. A cell experiment, animal model, exploratory analysis and controlled human trial answer different questions.
Prepared 05 November 2026. Regulatory status is jurisdiction- and date-specific. No claim of specialist review or exhaustive evidence coverage.
Transcript
IGF-1 LR3 | Engineered analogue
IGF-1 LR3, also called Long Arg3 IGF-I, is an engineered analogue. Its sequence differs from natural IGF-1, so the exact molecule matters. [1]
CELL STUDY | Binding and activity
An early study compared these analogues in cell models and examined interactions with IGF-binding proteins. Those experiments help explain laboratory activity, not clinical muscle gains. [1]
Mecasermin and LR3 are distinct
Mecasermin is a different prescription product with FDA-approved uses for specific pediatric growth disorders. Its approval does not establish an approval or benefit for LR3. [1] [2]
Match the evidence to the molecule
Changing a growth-factor molecule can change its behavior. Evidence must match the exact compound, outcome and population before laboratory potency becomes a clinical claim. [1] [2]
Sources and context
These linked sources support the evidence distinctions in this short overview. This is not a systematic review, endorsement or treatment recommendation.
- Francis et al. (1992): Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency →Long Arg3 IGF-I identity and cell-based comparison.
- FDA: INCRELEX (mecasermin) prescribing information, revised July 2025 →Mecasermin indication and identity; not LR3 evidence.
