About IGF-1 LR3

IGF-1 LR3 (Insulin-like Growth Factor-1 Long R3) is a synthetic analogue of human IGF-1. The “Long R3” modification — an extra 13 amino acids at the N-terminus and an arginine substitution at position 3 — does two things: it extends the plasma half-life from ~10 minutes (native IGF-1) to roughly 20–30 hours, and it reduces binding to IGFBP-3, leaving more of the peptide bioavailable at the receptor.

In research literature it’s primarily studied for muscle hyperplasia (proliferation of new muscle cells rather than just enlargement of existing ones), nerve regeneration, and IGF-1 receptor signalling. It’s a powerful compound — the long half-life and high receptor affinity mean dosing errors compound across days, so this is one to be conservative with.

Dosing observed in research literature

Application	Dose range	Frequency	Notes
General research dosing	20–40 mcg / day	Once daily	Post-workout common in literature
Higher-range research	40–80 mcg / day	Once or twice daily	Hypoglycaemia risk increases above 50 mcg
Site-specific (bilateral)	10–20 mcg per side	Post-workout, both sides	Studied for localised hyperplasia effect

Cycle length in research is typically 4 weeks on, 4 weeks off. Extended continuous use is poorly characterised in literature and may downregulate IGF-1 receptor sensitivity.

Typical reconstitution protocols

IGF-1 LR3 typically ships as a 1 mg lyophilised vial. Reconstitution recommendations:

Vial size	Recommended BAC water	Concentration	20 mcg draw	40 mcg draw
1 mg	1 mL	1000 mcg / mL	2 units (U-100)	4 units
1 mg	2 mL	500 mcg / mL	4 units	8 units
1 mg	0.5 mL	2000 mcg / mL	1 unit (precision-limited)	2 units

The 2 mL reconstitution is the practical sweet spot — draws of 4–8 units are easy to measure on a U-100 syringe and the vial lasts ~25 days at typical research doses, well inside the 28-day BAC shelf-life window.

Half-life and frequency

Published plasma half-life for IGF-1 LR3 is in the 20–30 hour range. That’s an order of magnitude longer than native IGF-1 (≈10 minutes) and supports the once-daily dosing pattern seen in most research protocols. Twice-daily dosing has been studied at lower per-dose amounts but adds little to total exposure given the slow elimination.

Storage and shelf life

Lyophilised (unmixed): store at 2–8°C refrigerated. Can be frozen at −20°C for long-term storage. Once reconstituted with bacteriostatic water: 28 days refrigerated. Don’t freeze a reconstituted vial — ice crystals damage the peptide.

Frequently asked questions

How much BAC water do I add to a 1 mg IGF-1 LR3 vial?

2 mL is the standard, giving 500 mcg/mL. A 20 mcg dose is then 4 units on a U-100 syringe, a 40 mcg dose is 8 units. Use the calculator at the top of this page to plug in any vial size + BAC water combination.

What’s the difference between IGF-1 LR3 and DES IGF-1?

IGF-1 LR3 has a long half-life (~20–30 hours), suiting once-daily systemic research. DES (Des(1-3) IGF-1) is the opposite — a short-acting analogue truncated at the N-terminus, with much higher local receptor binding and a half-life under 30 minutes. DES is studied for site-specific hyperplasia, LR3 for systemic effect.

Is IGF-1 LR3 affected by insulin sensitivity?

Yes — IGF-1 LR3 binds the insulin receptor at low affinity, but at higher doses (>50 mcg) it can cause hypoglycaemia. Research protocols typically dose post-meal to buffer this. Symptoms of hypoglycaemia (dizziness, sweating, hunger) are a sign to reduce dose.

Can IGF-1 LR3 be stacked with HGH?

This is studied in some research protocols — HGH stimulates endogenous IGF-1 production, and exogenous IGF-1 LR3 supplements the receptor-binding pool. Combined research dosing tends to keep IGF-1 LR3 at the lower end (20–30 mcg) to avoid additive hypoglycaemic effect.

How long does IGF-1 LR3 last after reconstitution?

28 days refrigerated when mixed with bacteriostatic water. If you used sterile water (no preservative), the window drops to 24–48 hours. Never freeze a mixed vial.

What injection site is used for IGF-1 LR3 research?

Subcutaneous abdominal injection is the most common. For site-specific hyperplasia research, bilateral intramuscular injection into the target muscle group is studied, though this is a more advanced technique outside the scope of typical research protocols.

Related compounds

IGF-1 LR3 is in the growth and performance research category. Adjacent compounds: Tesamorelin (stimulates endogenous IGF-1 via GHRH), HGH (Somatropin — upstream of IGF-1), Ipamorelin + CJC-1295 (GH-releasing stack). For full category context, see the Growth & Performance Peptides overview.