IGF-1 LR3
★ 85Long Arginine 3 Insulin-like Growth Factor 1
Long-acting IGF-1 analog for anabolic signaling
Muscle GrowthAbout
IGF-1 LR3 is a synthetic 83-amino-acid analog of human IGF-1 with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. These modifications reduce binding to IGF-binding proteins, extending its half-life roughly 2-3x versus native IGF-1. It is widely used in research contexts for muscle protein synthesis studies and has no published human clinical trials of its own.
Mechanism
Binds IGF-1R with high affinity and activates PI3K/Akt/mTOR (protein synthesis, glucose uptake) and RAS/RAF/MEK/ERK (proliferation) pathways.
Dosage
beginner
- Amount
- 20-40 mcg
- Frequency
- Once daily
- Route
- SubQ
- Duration
- 3-4 weeks
standard
- Amount
- 40-80 mcg
- Frequency
- Once daily
- Route
- SubQ or IM
- Duration
- 4-6 weeks
advanced
- Amount
- 80-100 mcg
- Frequency
- Once daily
- Route
- SubQ or IM
- Duration
- 4-6 weeks
Post-workout on training days; morning with food on rest days. Never inject fasted and never within 2 hours of bedtime. Consume 30-50g fast-acting carbohydrate within 30 minutes of injection.
3-6 weeks on, minimum equal time off (4-6 weeks). Continuous use is discouraged due to insulin resistance and receptor desensitization risk.
Reconstitution & Storage
50 mcg dose = 10 units on a U-100 insulin syringe.
Dosing reference — units to draw
Concentration = peptide mass ÷ bacteriostatic water; units to draw = dose volume (mL) × 100 on a U-100 insulin syringe. Each vial size below is shown at 1 mL, with the units to draw for a typical 100–200 mcg dose.
| Vial | BAC water | Concentration | Units to draw |
|---|---|---|---|
| 1 mg | 1 mL | 1000 mcg/mL | 10–20 units |
Lyophilized: -20°C freezer up to 12 months. Reconstituted: 2-8°C, use within ~28 days. Do not freeze reconstituted solution.
Benefits
- • Enhanced muscle protein synthesis
- • Anti-catabolic support during training
- • Possible localized hypertrophy with site-specific IM injection
- • Improved nutrient partitioning and glucose uptake into muscle
Side effects
- • Hypoglycemia (reported in ~42% of Increlex subjects, can be severe)
- • Lymphoid/tonsillar hypertrophy
- • Visceral organ growth (kidney, spleen) — largely irreversible
- • Fluid retention, joint discomfort, headaches
- • Injection-site lipohypertrophy
- • Possible feedback suppression of endogenous GH
Contraindications
- • Active or prior cancer history (mitogenic concern)
- • Diabetes or glucose dysregulation
- • Concurrent insulin or sulfonylurea therapy
- • Pregnancy and breastfeeding
- • Pre-existing cardiac, kidney, liver, or splenic disease
- • Adolescents with open growth plates
Gender notes
Men
Standard 40-80 mcg/day range. Monitor fasting glucose weekly during first cycle.
Women
Typically 10-20 mcg/day. Lower lean-mass baseline means higher sensitivity to anabolic and hypoglycemic effects.
Research
- Anabolic effects of insulin-like growth factor-I (IGF-I) variants in normal female rats ↗
Tomas et al. demonstrated that IGF-1 analogs with reduced IGFBP binding (including LR3) maintain superior anabolic potency versus native IGF-1 when injected, supporting protein retention in rat models.
Journal of Endocrinology · 1996
- Mecasermin (recombinant human IGF-1) for the treatment of short stature ↗
Pivotal Increlex data document hypoglycemia in ~42% of pediatric subjects and tonsillar hypertrophy in ~15%, informing the safety expectations for IGF-1 analog use.
Expert Opinion on Biological Therapy · 2007
- Detection of IGF-1 LR3 in human urine by mass spectrometry ↗
First validated WADA detection assay for IGF-1 LR3, confirming its abuse in sport and its banned status under category S2.
Drug Testing and Analysis · 2020
Stacks well with
IGF-1 LR3 FAQ
How do you reconstitute IGF-1 LR3?
Add 1 mL of bacteriostatic water to a 1 mg vial of IGF-1 LR3, which gives a concentration of 1000 mcg/mL. Inject the water slowly down the vial wall and swirl gently — never shake.
What is a typical IGF-1 LR3 dose?
A typical research dose of IGF-1 LR3 is 100–200 mcg, once daily. This is educational information, not medical advice.
How many units of IGF-1 LR3 do I draw?
From a 1 mg vial reconstituted with 1 mL of bacteriostatic water, draw 10–20 units on a U-100 insulin syringe for a 100–200 mcg dose.
Track IGF-1 LR3 doses in the app
Built-in reconstitution calculator, dose log, and reminders. Free on Android.
Get on Google PlayEducational use only. Not medical advice. Many peptides shown are not FDA-approved and remain research compounds. Always consult a qualified healthcare provider.