IGF-1 LR3
Long-R3 IGF-1 Β· Insulin-like Growth Factor-1 LR3 Β· Mecasermin analogue
Long-acting synthetic analogue of IGF-1 with an N-terminal extension and Arg-3 substitution that reduces binding to IGF binding proteins (IGFBPs), extending half-life from ~15 min (native IGF-1) to ~20β30 hours. Mediates many anabolic and tissue-repair effects downstream of GH signalling.
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Mechanism of Action
Binds IGF-1 receptors (IGF1R) with high affinity; reduced IGFBP binding means a greater fraction of injected peptide remains free and bioavailable. Activates PI3K/Akt and MAPK/ERK pathways to drive protein synthesis, cell proliferation, glucose uptake, and satellite cell activation in skeletal muscle.
Clinical Applications
- βLean muscle mass accretion and body composition improvement
- βPost-injury muscle repair and prevention of atrophy
- βGH-axis optimisation β downstream amplification when GH is optimised
- βRecovery from surgery or extended immobilisation
Dosing Protocol
Recommended Dosing
SC or IM injection. 20β60 mcg/day (research range); conservative start: 20 mcg bilaterally in target muscle groups post-workout. Due to 20β30 h half-life, daily dosing is sufficient. Cycle: 4β6 weeks maximum, then minimum 6-week break. Monitor fasting glucose closely.Safety & Contraindications
Possible Side Effects
- β Hypoglycaemia β most significant risk; inject post-meal or post-workout
- β Joint pain and fluid retention (similar to GH excess)
- β Jaw/facial tissue growth with prolonged high-dose use (acromegaloid effects)
- β Potential lipoma formation at injection sites with repeated dosing
Contraindications
- βActive malignancy β IGF1R is overexpressed on many cancer cell types; IGF-1 LR3 is strongly contraindicated
- βDiabetic retinopathy
- βAcromegaly or elevated baseline IGF-1
- βHypoglycaemia-prone individuals (must eat within 30 min of injection)