IGF-1 LR3
Also known as: Long R3 IGF-1, Long Arginine IGF-1
Modified Growth Factor Analog | Muscle Growth
Overview
IGF-1 LR3 is a synthetic 83-amino acid analog of insulin-like growth factor-1 that has never been approved for human use. The N-terminal extension and R3 substitution reduce binding protein interaction, maintaining elevated free circulating levels with ~3x greater potency than native IGF-1.
Key benefits
- Approximately 3x more potent than native IGF-1
- Promotes muscle hypertrophy and hyperplasia in animal models
- 15-20% lean mass gains observed in 4-week rat studies
- Anti-catabolic effects preserve muscle during cachexia
- 20-30 hour half-life for sustained effects
Mechanism of action
Functions as a full IGF-1 receptor agonist activating PI3K/Akt/mTOR and MAPK/ERK pathways. The modifications prevent protein sequestration, maintaining elevated free circulating levels for extended anabolic effects.
Molecular data
- Type
- Synthetic IGF-1 analog
- Half-life
- 20-30 hours
Indications
What the research community uses this compound for, with self-reported effectiveness.
Muscle Growth
Hypertrophy
Most effective15-20% lean mass gains in 4 weeks through satellite cell activation (rat studies).
Anti-Catabolic
EffectiveCancer cachexia rats maintained 30% more muscle versus placebo.
Hyperplasia
EffectiveCreates new muscle fibers via satellite cell differentiation.
Tissue Repair
Wound Healing
EffectiveAccelerated wound healing in animal models.
Ligament/Tendon Recovery
ModerateEnhanced connective tissue repair.
Metabolic
Nutrient Partitioning
ModerateDirects nutrients toward muscle tissue.
Fat Loss
ModerateEnhanced lipolysis through IGF-1 pathway.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Injectable
Subcutaneous or intramuscular injection. CRITICAL: Consume 30-60g fast carbohydrates immediately after injection to prevent hypoglycemia. Never inject before sleep.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| Beginner Protocol | 20-30mcg | Once daily post-workout | SubQ/IM |
| Intermediate | 40-60mcg | Once daily | SubQ/IM |
| Advanced | 80-100mcg | Once or split AM/PM | SubQ/IM |
| Women's Protocol | 10-20mcg | Once daily | SubQ/IM |
Preparation
You will need
- IGF-1 LR3 lyophilized powder
- 0.6% acetic acid OR bacteriostatic water
- Insulin syringes (29-32 gauge)
- Alcohol swabs
Steps
- Equilibrate to room temperature (15-30 min)
- Sanitize rubber stopper with alcohol
- Calculate concentration (e.g., 1mg in 2mL = 500mcg/mL)
- Inject diluent slowly along vial wall
- Gently swirl - never shake vigorously
- Allow 2-5 minutes for complete dissolution
- Store immediately at 2-8°C protected from light
- Acetic acid reconstitution: stable 1 year
- BAC water reconstitution: use within 7 days
Work out the water volume and syringe units in the reconstitution calculator →
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
Human Growth Hormone
AvoidCreates excessive IGF-1 levels; avoid combination.
Insulin
AvoidSynergistic hypoglycemic effects can be life-threatening.
CJC-1295/Ipamorelin
MonitorBoth stimulate GH/IGF-1 axis; use caution with combination.
MK-677
MonitorMay compound metabolic effects through GH stimulation.
Anabolic Steroids
MonitorAmplified effects with increased risks.
Metformin
MonitorMay mitigate insulin resistance.
Cerebrolysin
MonitorAdditive neurotrophic pathway effects.
BPC-157
SynergisticComplementary healing mechanisms.
TB-500
SynergisticDifferent repair pathway activation.
Timeline
Typical week-by-week effects reported in clinical and observational data.
- Week 1-2
Increased muscle pump and fullness; possible hypoglycemia if carbs inadequate
- Week 2-4
Enhanced recovery, strength gains, visible fullness, potential water retention
- Week 4-6
Maximum effects; receptor desensitization approaching; joint stiffness common
- Post-cycle
Pump loss over 1-2 weeks; strength/size gains may persist with training
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Hypoglycemia (lasting up to 30 hours) - CRITICAL
- Water retention
- Joint stiffness
- Muscle soreness
- Increased pump during workouts
Stop signs — stop and seek advice
- Severe or recurring hypoglycemia despite carbohydrate intake
- Unusual growths, lumps, or rapid mole changes
- Severe joint pain or carpal tunnel symptoms
- Persistent nausea, headaches, or vision changes
- Signs of organ enlargement
- Extreme fatigue or mental fog
Contraindications
- NEVER approved for human use - research chemical only
- Cancer history or undiagnosed growths
- May cause organ hypertrophy (heart, intestines)
- WADA prohibited - causes failed drug tests
Monitoring
- CRITICAL: Consume 30-60g fast carbohydrates immediately after injection
- Never inject before sleep (overnight hypoglycemia risk)
- Monitor blood glucose regularly, especially week one
- 4-6 week maximum cycle; equal off-period required
Quality checks
What a legitimate product looks like, what should give pause, and what should make you stop.
Good signs
- HPLC purity >95%
- Mass spectrometry confirmation
- Cold storage maintained (-20°C lyophilized)
- Certificate of analysis from reputable source
Warning signs
- Research chemical status - never approved for human use
- Zero human clinical trials exist
- Species-specific responses vary significantly
Stop signs — don't use
- Severe hypoglycemia risk - life-threatening low blood sugar lasting 20-30 hours
- Cancer proliferation concern - UK Biobank links elevated IGF-1 to multiple cancers
- Black market quality varies - oxidized and degraded forms common
Recent research
Newer papers and trial readouts on file for this compound, with source and date.
November 2024 · Alzheimer's & Dementia
Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice
7-month intranasal LR3-IGF-1 treatment improved body composition and reduced filamentous plaques in cortex of Alzheimer's model mice, but failed to preserve cognitive function. Suggests potential for combinatorial approaches rather than monotherapy.
January 2025 · American Journal of Physiology
IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep
1-week IGF-1 LR3 treatment did not improve growth in growth-restricted fetal sheep. Amino acid concentrations decreased in LR3 group, highlighting species- and context-specific responses.
References
Primary literature and clinical-trial data informing this entry.
Insulin-like growth factor-I (IGF-I) and especially IGF-I variants are anabolic in dexamethasone-treated rats
Tomas FM, Knowles SE, Owens PC, Chandler CS, Francis GL, Read LC, Ballard FJ · Biochemical Journal · 1992
LR3IGF-I was approximately 2.5-fold more potent than native IGF-1 in reversing dexamethasone-induced catabolism. 7-day treatment showed significant body weight recovery vs 19g loss in controls.
Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets
Stremming J, White A, Galan HL, Brown LD · American Journal of Physiology - Regulatory, Integrative and Comparative Physiology · 2023
Fetal plasma insulin concentrations decreased 66% with IGF-1 LR3 infusion during hyperglycemic clamp. Insulin secretion suppression was acute and did not persist in isolated islets.
Insulin-like growth factor I preserves host lean tissue mass in cancer cachexia
Ng EH, Rock CS, Lazarus DD, Stiaino-Coico L, Moldawer LL, Bhatt GR · American Journal of Physiology · 1992
IGF-1 treatment effectively attenuated host muscle protein and lean tissue depletion in a sarcoma model without stimulating tumor growth. Dose-dependent increases in carcass weight and gastrocnemius muscle protein.
Circulating Insulin-like Growth Factor-I Concentrations and Risk of 30 Cancers: Prospective Analyses in UK Biobank
Murphy N, Knuppel A, Papadimitriou N, Martin RM, Tsilidis KK, Brennan P et al. · Cancer Research · 2020
Higher circulating IGF-1 associated with increased risks of colorectal, breast, prostate, and thyroid cancers in the UK Biobank prospective cohort of >395,000 participants.
Last updated . How this page was sourced is described in the methodology.