IGF-1 LR3
Direct anabolic signalling via IGF-1 receptor — enhanced potency with 20–30× longer half-life than native IGF-1.
Research facts
| Half-life | 20–30h |
|---|---|
| Route | SubQ / IM |
| Typical dose | 20–60 mcg/day |
| Frequency | Once daily (post-training or AM) |
| Solvent | Acetic acid 0.1%, then dilute in BAC water |
| pH | 2.5–3.5 stock, dilute to 5.5–7.0 |
| Stability | 21 days at +4°C post-reconstitution |
Mechanism of action
IGF-1 LR3 is a long-acting recombinant analogue of Insulin-like Growth Factor 1, incorporating an arginine substitution at position 3 and an N-terminal extension that reduces binding to IGF-binding proteins (IGFBPs) — extending the active half-life from ~10–15 minutes to 20–30 hours.
It directly activates the IGF-1 receptor (IGF-1R), a receptor tyrosine kinase that initiates PI3K/Akt and MAPK signalling cascades. These pathways drive cellular hypertrophy, satellite cell activation, glucose uptake, and anti-apoptotic signalling. The reduced IGFBP binding means more free, biologically active hormone is available.
IGF-1 LR3 bypasses the liver, acting directly on peripheral tissues. It has direct hypoglycaemic effects via insulin-receptor cross-activation and muscle glucose transporter (GLUT-4) upregulation — the primary safety concern.
Documented effects (research-model)
- Direct muscle protein synthesis and hypertrophy via IGF-1R
- Satellite cell activation for muscle regeneration
- Glucose uptake in skeletal muscle (GLUT-4 upregulation)
- Anti-catabolic during caloric deficit
- Neuroprotection and BDNF upregulation
- Enhanced GH axis downstream effects
Research protocols
| Protocol | Dose | Frequency | Cycle | Vial |
|---|---|---|---|---|
| Standard | 20–40 mcg/day SubQ | Once daily (post-training) | 4–6 weeks maximum | 1mg / dilute per protocol |
| Advanced | 50–60 mcg/day | Once daily, fasted | 4 weeks then 4 weeks off | 1mg stock |
Research context only. Not medical advice. Consult a qualified healthcare professional before any protocol decision.
Synergies
- Ipamorelin MODERATE
Ipamorelin elevates endogenous GH→IGF-1; IGF-1 LR3 adds direct IGF-1R activation. Dual-pathway GH axis stimulation. - BPC-157 MODERATE
BPC-157 repairs tissue; IGF-1 LR3 drives hypertrophic signalling in that repaired tissue.
Myths & misconceptions
Evidence gaps
- Long-term cancer risk at research doses is genuinely unknown — no prospective human safety trials exist.
- Optimal dosing timing (pre vs. post training) not established by controlled trial.
- Hypoglycaemia risk profile in non-diabetic healthy subjects not systematically studied.
Safety notes
CRITICAL: Hypoglycaemia risk is real — monitor blood glucose, have fast-acting carbohydrates available. Not suitable for diabetics on insulin without medical supervision. Do not combine with insulin. Monitor IGF-1.
Biomarkers to monitor
Primary-source citations
- PMID 7962289 — Long R3-IGF-I and IGF-I in vitro and in vivo: comparison in GH-deficient rats (Endocrinology. 1994)
Frequently asked
What is IGF-1 LR3?
IGF-1 LR3 (Long R3 Insulin-like Growth Factor 1) is a research compound classified in our library as Tier C — Limited human trials; effect size uncertain.. Direct anabolic signalling via IGF-1 receptor — enhanced potency with 20–30× longer half-life than native IGF-1.
What is the evidence tier for IGF-1 LR3?
We classify IGF-1 LR3 as Tier C: Limited human trials; effect size uncertain. See our full peptide evidence tiers explainer for how we assign S/A/B/C/D.
What is the research dose of IGF-1 LR3?
For IGF-1 LR3, typical research dose is 20–60 mcg/day, route is SubQ / IM, half-life is 20–30h. Protocols vary by research goal — see the protocols section on this page for standard and advanced dosing schedules. Research use only, not medical advice.
Is IGF-1 LR3 safe?
CRITICAL: Hypoglycaemia risk is real — monitor blood glucose, have fast-acting carbohydrates available. Not suitable for diabetics on insulin without medical supervision. Research context only — no compound on this site is approved for human therapeutic use unless explicitly noted.