IGF-1 LR3

Volume Pricing

Price per pack (10 vials). Discount applies to this compound only – no mix and match.

IGF-1 LR3 — IGF-1R Agonist | Long-Acting Insulin-Like Growth Factor Analog

IGF-1 LR3 (Long Arginine 3-Insulin-Like Growth Factor-1) is an 83-amino acid synthetic analog of human insulin-like growth factor-1 (IGF-1), engineered with two deliberate structural modifications that dramatically expand its biological activity relative to the native hormone. The “Long” designation refers to a 13-amino acid N-terminal extension, and “R3” denotes the substitution of arginine for glutamic acid at the third position. Together, these changes eliminate IGF-1 LR3’s binding affinity for insulin-like growth factor binding proteins (IGFBPs) — the circulating carrier proteins that normally sequester and rapidly inactivate native IGF-1. The result is a compound with a half-life of approximately 20–30 hours (versus IGF-1’s ~12–15 hours), approximately 3-fold greater potency, and dramatically increased free bioavailability — making it one of the most pharmacologically powerful IGF-axis research tools available.

Why IGFBP Resistance Is the Defining Feature

Native IGF-1 is tightly bound by six IGF-binding proteins at any given time, with approximately 98% of circulating IGF-1 rendered inactive by IGFBP sequestration. This creates an extremely short window of receptor-available IGF-1 activity and limits the utility of native IGF-1 in research settings requiring sustained pathway engagement.

IGF-1 LR3 bypasses this entirely. By eliminating IGFBP binding, virtually all circulating IGF-1 LR3 remains free and receptor-available — allowing researchers to study sustained IGF-1 receptor signaling at the cellular level without the confounding degradation kinetics that constrain native IGF-1 studies.

Upon binding IGF-1R — a receptor tyrosine kinase structurally homologous to the insulin receptor — IGF-1 LR3 activates two major downstream signaling cascades:

Because IGF-1 LR3 acts downstream of the pituitary-liver GH/IGF-1 axis — bypassing the need for GH-stimulated hepatic IGF-1 synthesis — it allows researchers to directly interrogate tissue-level IGF-1R signaling without the upstream variability of endogenous GH secretion.

Research Applications

IGF-1 LR3 is used in studies examining:

• IGF-1 receptor binding kinetics, internalization dynamics, and downstream phosphorylation profiles
• PI3K/Akt/mTOR and MAPK/ERK pathway activation in proliferative and differentiating cell models
• Skeletal muscle satellite cell activation, hypertrophy, and hyperplasia under sustained IGF-1R stimulation
• Muscle regeneration models following injury — including laceration, contusion, and strain-based paradigms
• Bone mineral density, osteoblast proliferation, and bone formation dynamics
• Glucocorticoid-induced catabolism attenuation via IGF-axis upregulation
• Glucose uptake regulation, insulin sensitivity modulation, and metabolic signaling crossover between IGF-1R and insulin receptor
• Body composition and lean mass changes under sustained anabolic signaling
• Receptor desensitization dynamics and cycling protocols for sustained IGF-1R responsiveness
• Comparative studies between IGF-1 LR3, native IGF-1, and IGF-1 DES variants

Specifications

Reconstitution

IGF-1 LR3 arrives as lyophilized powder and must be reconstituted with bacteriostatic water prior to use. Due to its high potency — active at microgram (mcg) doses — precise concentration calculation is essential for accurate dosing in research protocols. Use the formula:

Total mg ÷ Volume added (mL) = Concentration (mg/mL)

Example: 1mg vial + 2mL BAC water = 0.5mg/mL (500mcg/mL) solution — each 0.1mL = 50mcg Example: 1mg vial + 1mL BAC water = 1mg/mL (1,000mcg/mL) solution — each 0.1mL = 100mcg Example: 0.1mg vial + 1mL BAC water = 0.1mg/mL (100mcg/mL) solution — each 0.1mL = 10mcg

Add bacteriostatic water slowly by angling the needle against the inside wall of the vial — do not inject directly onto the powder. Gently swirl to dissolve; do not shake, as agitation can disrupt the peptide’s tertiary structure and reduce receptor binding activity. Reconstituted IGF-1 LR3 should be stored at 2–8°C and used within 28–30 days.

Protocol Notes

IGF-1 LR3’s extended 20–30 hour half-life means once-daily dosing is standard in research models. Because it remains active throughout the day, cycling is a critical protocol variable — continuous use promotes IGF-1R desensitization and diminishing returns; structured on/off cycles preserve receptor sensitivity across the study window.

Typical research dosing framework:

• Starting dose: 20–40mcg per administration
• Escalation: Increase by 10–20mcg increments every 5–7 days based on experimental parameters
• Target range: 20–50mcg daily (conservative protocols); up to 80–100mcg in advanced in vivo models
• Frequency: Once daily
• Cycle structure: 4–6 weeks on, equal time off — critical for maintaining receptor responsiveness
• Timing: Post-exercise administration is commonly used in tissue modeling studies to align with peak satellite cell activation and nutrient uptake windows

Commonly observed effects in research models:

• Metabolic: Increased glucose uptake into cells; enhanced insulin sensitivity at moderate doses; hypoglycemia risk at higher doses — particularly in fasted states
• Anabolic: Elevated protein synthesis markers; satellite cell activation; lean mass accrual in sustained-dosing animal models
• Injection site: Mild transient irritation; rotate injection sites systematically
• Other: Water retention and joint tightness at higher doses; headache reported anecdotally; receptor desensitization with continuous use beyond 6 weeks; theoretical mitogenic risk warrants careful monitoring in cell proliferation studies

Research Stacks

IGF-1 LR3 is commonly paired in research settings with:

• MGF — MGF (Mechano-Growth Factor) is an IGF-1 splice variant that activates a distinct receptor domain and promotes satellite cell activation; co-administration studies examine whether MGF’s acute local signaling and IGF-1 LR3’s systemic, prolonged IGF-1R engagement produce complementary or additive effects on myogenic proliferation.
• GHRP-2 — GHRP-2 stimulates pituitary GH release via the ghrelin receptor, transiently elevating endogenous GH and downstream IGF-1 production; pairing with exogenous IGF-1 LR3 allows researchers to compare or combine receptor-level and systemic IGF axis activity.
• Ipamorelin — Ipamorelin is a selective GH secretagogue with minimal off-target hormonal activity; combining it with IGF-1 LR3 is studied to probe the GH/IGF axis at both the secretagogue and effector levels within the same experimental model.

Purity Guarantee

Every batch is ≥99% purity. If you independently test your compound and the results don’t match — send us the COA and we’ll issue store credit, no questions asked.