IGF-1 LR3
Also known as: Long R3 IGF-1, Receptor Grade IGF-1
Molecular Identifiers
Molecular Formula
C400H625N111O115S9
CAS Number
946870-92-4
PubChem CID
168009904Molecular Weight
~9.1 kDa
Overview
Long-acting analog of insulin-like growth factor type 1 (IGF-1). Modified with Arg→Glu substitution at position 3 and 13-amino acid N-terminal extension, resulting in reduced affinity for IGFBPs and significantly longer half-life.
The main clinical interest around IGF-1 LR3 lies in its direct anabolic effects on muscle tissue: IGF-1R receptor activation with increased affinity, stimulation of protein synthesis, hyperplasia (myoblast proliferation), and an anti-catabolic effect. Compared to native IGF-1, the significantly longer half-life allows a single daily dose with sustained effect.
IGF-1 LR3 currently has no regulatory approval from any agency (FDA, EMA, ANVISA) for human use, and its use is described almost exclusively in bodybuilding and sports medicine. It is dispensed by compounding pharmacies as off-label use, in short 4-6 week cycles with equal off intervals to avoid receptor desensitization. The risk of hypoglycemia requires glucose monitoring. WADA lists IGF-1 and its analogs as substances prohibited at all times for competitive athletes.
Within the IGF axis, it is often compared with MGF: while IGF-1 LR3 acts systemically via the IGF-1R receptor, with a long half-life and global anabolic stimulus, MGF is an alternative splice product of the same gene, with a localized action focused on muscle satellite cell activation. The two are commonly stacked in sports cycles because their mechanisms are complementary.
MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSA Met-Phe-Pro-Ala-Met-Pro-Leu-Ser-Ser-Leu-Phe-Val-Asn-Gly-Pro-Arg-Thr-Leu-Cys-Gly-Ala-Glu-Leu-Val-Asp-Ala-Leu-Gln-Phe-Val-Cys-Gly-Asp-Arg-Gly-Phe-Tyr-Phe-Asn-Lys-Pro-Thr-Gly-Tyr-Gly-Ser-Ser-Ser-Arg-Arg-Ala-Pro-Gln-Thr-Gly-Ile-Val-Asp-Glu-Cys-Cys-Phe-Arg-Ser-Cys-Asp-Leu-Arg-Arg-Leu-Glu-Met-Tyr-Cys-Ala-Pro-Leu-Lys-Pro-Ala-Lys-Ser-Ala Modified IGF-1 analog with 83 amino acids. 13 aa N-terminal extension.
Half-life
~20-30 hours
Administration Route
Subcutaneous or intramuscular
Category
Metabolic & Fat Loss
Mechanism of Action
- IGF-1R receptor activation with increased affinity
- Promotion of protein synthesis and muscle hypertrophy
- Anti-catabolic effect
- Cell proliferation and differentiation
- Prolonged half-life due to low affinity for IGFBPs
Dosage Protocol
Data compiled from the literature. This does not constitute medical advice.
| Parameter | Value |
|---|---|
| Dose | 20-50 mcg per injection |
| Frequency | Once daily (training days) |
| Timing | Immediately post-workout |
| Duration | 4-6 weeks (with equal off intervals) |
Reported Side Effects
Adverse effects described in the literature. Severity and frequency vary between individuals.
- Hypoglycemia
- Joint pain
- Swelling
- Headache
- Numbness in extremities
Product Properties
| Purity | >95% |
| Appearance | White lyophilized powder |
| Solubility | Soluble in water and bacteriostatic water. Acidic solutions (0.1M acetic acid) recommended for long-term stability. |
| Source | Recombinant DNA technology (E. coli) |
| Storage | Lyophilized: -20°C for up to 2 years, 2-8°C for up to 3 months. Reconstituted: 2-8°C for up to 2 weeks. Keep frozen for long-term storage. Protect from light and moisture. Avoid repeated freeze-thaw cycles. |
Presentations & Preparation
Vials of IGF-1 LR3 found in the research market:
Reconstitution
- Diluent: Bacteriostatic water or 0.6% acetic acid
- Volume: 1 ml per 1 mg vial
- Inject diluent slowly against the vial wall
- Gently swirl
- Never shake — sensitive protein
Storage
- Lyophilized: Frozen -20°C (long-term)
- Reconstituted: Refrigerated 2-8°C (up to 30 days)
- Sensitive protein — avoid shaking
- Protect from light
Scientific Studies
Published studies on IGF-1 LR3.
Long R3 insulin-like growth factor-I (IGF-I) infusion stimulates organ growth but reduces plasma IGF-I, IGF-II and IGF binding protein concentrations in the guinea pig
Conlon MA, Tomas FM, Owens PC, Wallace JC, Howarth GS, Ballard FJ
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
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