IGF-1 LR3
Also known as: Long R3 IGF-1, Insulin-like Growth Factor-1 Long R3
IGF-1 LR3 is a modified version of insulin-like growth factor-1 (IGF-1) with a longer half-life. The modifications make it more potent and prevent binding to IGF-binding proteins, allowing it to remain active in the body longer. It promotes muscle growth and fat loss.
Research Status
Research compound - not FDA approved
For research purposes only. Not approved for human use. Not medical advice.
Research Areas
Side Effects
IGF-1 LR3 dramatically increases glucose uptake in muscle tissue, lowering blood glucose. Symptoms include tremor, sweating, dizziness, confusion, and rapid heartbeat. Manage by consuming fast-acting carbohydrates (glucose tablets, juice, honey) immediately. Always have carbs available during and after injection. Avoid fasting during the first 2-4 hours post-injection. Monitor blood glucose if diabetic or pre-diabetic.
IGF-1 LR3 stimulates rapid tissue growth, including connective tissue, which can cause joint discomfort, particularly in the knees, shoulders, and wrists. This is typically self-resolving and mild. Manage with rest, ice, and NSAIDs if needed. Ensure adequate hydration and electrolyte intake. Symptoms usually resolve within days of discontinuation.
Rapid growth of connective tissue in the wrist can compress the median nerve, causing numbness, tingling, or pain in the hand. This is more common with prolonged use beyond 4 weeks. Manage by wearing a wrist splint at night, reducing injection frequency, or discontinuing use. Symptoms typically resolve within 1-2 weeks of stopping the peptide.
Repeated injections at the same site cause localized fat loss (lipoatrophy) or, less commonly, fat gain (lipohypertrophy). This is cosmetic and reversible. Prevent by strictly rotating injection sites with each dose, maintaining at least 1-1.5 inches between injection points, and avoiding the same site more than once per week. Affected areas typically normalize within 3-6 months of proper rotation.
Local inflammation, erythema, or pruritus at the injection site can occur due to the peptide itself or improper injection technique. Manage by ensuring proper site rotation, using sterile technique, and allowing the solution to reach room temperature before injection. Apply ice if swelling occurs. Reactions typically resolve within 24 hours.
Mild to moderate headaches have been reported, possibly related to rapid metabolic changes or hypoglycemia. Manage by ensuring adequate carbohydrate intake post-injection and staying well-hydrated. Headaches typically resolve within hours.
Mild nausea can occur, particularly if injected on an empty stomach or if hypoglycemia develops. Manage by eating a small meal 30-60 minutes before injection and consuming carbohydrates post-injection. Nausea is typically transient.
Mild peripheral edema or water retention can occur due to increased protein synthesis and metabolic activity. Manage by maintaining adequate hydration and electrolyte balance. Edema typically resolves within days of discontinuation.
Prolonged IGF-1 LR3 use beyond 4 weeks can cause acromegaly-like changes including jaw enlargement, hand/foot growth, and facial coarsening. These changes are largely irreversible. Strictly adhere to the 4-week maximum cycle length. Discontinue immediately if any signs of acromegaly develop.
Chronic IGF-1 elevation can stimulate growth of internal organs (heart, liver, kidneys) and increase cancer risk. This is a theoretical concern with prolonged use. Limit use to 4-week cycles with extended breaks (at least 4-8 weeks) between cycles. Do not exceed recommended dosages or cycle duration.
Anaphylaxis or severe allergic reactions are rare but possible. Symptoms include difficulty breathing, throat tightness, severe rash, or swelling of face/lips. Seek emergency medical attention immediately if these occur. Have an epinephrine auto-injector available if you have a history of peptide allergies.
Dosing Reference
| Parameter | Value |
|---|---|
| Dose range | 20-100 mcg |
| Frequency | Daily for maximum 4 weeks |
| Timing | Post-workout preferred |
| Route | Subcutaneous, Intramuscular |
Very potent. Start low (20-40mcg). Can cause hypoglycemia - have fast carbs available. Do not exceed 4 weeks.
Research disclaimer
Figures drawn from published research literature and community logs. Not clinical recommendations. Consult a qualified professional. Research use only.
Reconstitution Guide
Do not use saline or bacteriostatic saline — use only bacteriostatic water for reconstitution
Do not shake the vial vigorously; gentle swirling prevents peptide degradation
Discard immediately if the solution appears cloudy, discolored, or contains visible particles
Use within 30 days of reconstitution when stored at 2–8°C
Do not freeze the reconstituted solution; freezing may denature the peptide
Use the PeptideVolt reconstitution calculator for your exact concentration
Molecular and Pharmacological Data
| Molecular weight | 8949 |
| Half-life | 20-30 hours (compared to 10-20 minutes for native IGF-1) |
| Sequence | MGFPLDPKFPQPPTINSQFVNWQVSGCGSASCVLSAGPATDTANYQRDVN |
IGF-1 LR3 is a synthetic analog of insulin-like growth factor-1 (IGF-1) engineered with an extended N-terminus (13 amino acids added) and arginine substitution at position 3, which dramatically increases its half-life and reduces binding to IGF-binding proteins (IGFBPs). This allows IGF-1 LR3 to remain bioactive in circulation 20-30 times longer than native IGF-1, promoting sustained anabolic signaling through the IGF-1 receptor. It stimulates protein synthesis, inhibits protein breakdown, enhances glucose uptake, and promotes lipolysis, resulting in lean muscle gain and fat loss.
IGF-1 Receptor (IGF-1R) Activation
IGF-1 LR3 binds to the IGF-1 receptor on muscle cells, activating the PI3K/Akt and MAPK/ERK signaling cascades. These pathways increase protein synthesis via mTOR activation and inhibit protein degradation via FoxO suppression, driving net muscle hypertrophy.
Glucose Metabolism and Insulin Sensitivity
IGF-1 LR3 enhances glucose uptake in muscle tissue via GLUT4 translocation and improves insulin sensitivity. However, this can lower blood glucose, particularly during fasting or high-intensity exercise, necessitating carbohydrate availability.
Lipolysis and Fat Oxidation
IGF-1 LR3 promotes lipolysis by increasing hormone-sensitive lipase activity and enhancing fatty acid oxidation in adipose tissue, contributing to fat loss while muscle is being built.
IGFBP Evasion
The structural modifications of IGF-1 LR3 reduce its binding affinity to IGF-binding proteins (IGFBP-3, IGFBP-5), allowing it to remain free and bioactive in circulation much longer than native IGF-1, which is rapidly sequestered by IGFBPs.
- IGF-1 LR3 has a 20-30 fold longer half-life than native IGF-1 due to reduced IGFBP binding and the extended N-terminus
- It is a potent anabolic agent that increases protein synthesis and decreases protein breakdown simultaneously
- IGF-1 LR3 significantly enhances glucose uptake and can cause hypoglycemia, especially during fasting or intense exercise
- The peptide acts systemically (not locally) once absorbed, affecting muscle, adipose tissue, and metabolic rate
- It has been studied in clinical settings for muscle wasting and aging but is not approved for human use outside research contexts
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