IGF-1 LR3 1mg · Long R3 IGF-1 (extended half-life IGF-1 analog) · 99.0% Purity

What is IGF-1 LR3?

IGF-1 LR3 (Long R3 IGF-1) is a modified analog of insulin-like growth factor-1 with an arginine-3 substitution and a 13-amino-acid N-terminal extension. These modifications drastically reduce binding to IGF binding proteins (IGFBPs), extending the systemic half-life from ~10 minutes (native IGF-1) to 20-30 hours, making it a powerful tool in muscle and recovery research.

What is IGF-1 LR3 used for?

Most-studied applications: skeletal muscle hypertrophy research, satellite cell activation, and post-injury recovery. Frequently stacked with MGF (IGF-1Ec) — the two represent the systemic and local arms of IGF-axis signaling respectively. Pairs well with Ipamorelin and CJC-1295 for GH-axis amplification.

How does it work?

Modified IGF-1 analog with Arg3 substitution and 13-amino-acid N-terminal extension; reduces IGFBP binding, extending half-life 100x over native IGF-1. Read our complete research hub for the full literature review, or jump to our best peptides for muscle article for comparator molecules.

Why this listing?

Because IGF-1 LR3 stimulates rapid hyperplasia in muscle research models, dose timing matters — pre-training and post-training protocols differ. Vanta Bio's batch IGF-2604-B tested 99.0% pure by HPLC.

How Peptide.best sources and verifies IGF-1 LR3

Every IGF-1 LR3 listing on Peptide.best comes from a verified vendor that has passed our onboarding audit — GMP-licensed manufacturing facility, documented chain of custody, third-party Janoshik Analytical testing on every batch, and a published Certificate of Analysis. Vanta Bio (the seller on this listing) currently maintains a 4.8-star average across all their products. Compare the five live offers on the right side of this page — Peptide.best forces vendors to compete on price and purity for the same SKU, so you always see the best current deal at the top, with the COA-verified purity, shipping speed, and seller rating side-by-side. Looking for alternatives in the same muscle space? MGF and the other peptides listed under our Muscle category are the most commonly compared alternatives.

Commonly stacked with

MGF · Ipamorelin · CJC-1295 · TB-500. See the peptide stacks page for full protocol writeups.

Compliance notice

IGF-1 LR3 has not been evaluated by the FDA for any indication. All statements on this page are based on published research and are not medical claims. Some products may be sold for research purposes only as marked. Consult a licensed healthcare provider before use. See our full disclaimer.

Research literature

IGF-1 LR3 has been the subject of growing peer-reviewed and preclinical research across the muscle domain. The current PubMed index returns several hundred citations spanning mechanism, dose-response, and adverse-event reporting.

Key references commonly cited in IGF-1 LR3 research:

• Mechanism papers covering modified igf-1 analog with arg3 substitution and 13-amino-acid n-terminal extension; reduces igfbp binding, extending half-life 100x over native igf-1.
• Dose-response work in rodent models (most studied species)
• Comparator-molecule trials vs. MGF and other peptides in the same class
• Safety / pharmacovigilance datasets where available

For a full reference list, see the Peptide.best Research Hub or the dedicated Muscle pillar article.

Standard research dosing

Standard research dose: 20–50 mcg subcutaneous, once daily (or bilateral IM near target muscle), 4-week cycles maximum, with extended off periods.

Reconstitution

This product ships as lyophilized powder. Reconstitute with Bacteriostatic water (1mL) for stable refrigerated storage. Once reconstituted, use within 30 days; keep at 2–8°C.

Protocol notes

For full protocols and stacking guidance, see our peptide dosing guides. Always start at the low end of the published range and titrate based on individual response. Half-life (~20-30 hours (vs. ~10 min for native IGF-1)) determines dosing frequency.

Reported side effects

Hypoglycemia (most important — always have carbohydrate available), transient injection-site lump, occasional GI bloating. Long-term IGF elevation is a theoretical concern for cell-proliferation pathways.

Contraindications

Do not use during pregnancy or lactation. Do not combine with other peptides without reviewing pharmacology. Consult a licensed healthcare provider before beginning any peptide research protocol. Discontinue immediately if any adverse reaction occurs and contact your provider.

Drug interactions

Limited interaction data exists for most research peptides. Be especially cautious when combining with prescription medications affecting the same physiological pathway as IGF-1 LR3 (muscle pathway).

Certificate of Analysis

Every batch of IGF-1 LR3 sold on Peptide.best ships with a third-party Certificate of Analysis (COA) from Janoshik Analytical — the most-cited independent peptide testing lab in the research community.

Current batch testing summary

• Batch ID: IGF-2604-B
• Test date: 04/14/2026
• Peptide content (HPLC): 99.0%
• Mass-spec identity: Confirmed (target mass match)
• Endotoxin (LAL): Below detection limit
• Residual solvents: Within USP <467> limits

Download full COA PDF

For our overall testing process and chain-of-custody details, see Trust & Safety.

Q: Is IGF-1 LR3 legal to purchase?

A: IGF-1 LR3 is sold on Peptide.best for research purposes where applicable. Legal status varies by jurisdiction. See our disclaimer for full details.

Q: How long until I see effects?

A: Timing depends on protocol, dose, and individual response. Most users report observable changes within 2–6 weeks of consistent dosing per the standard research protocols. See the Dosing & Protocol tab.

Q: Can I stack IGF-1 LR3 with other peptides?

A: Yes — see commonly stacked peptides in the Overview tab, or browse our peptide stacks page for full protocol writeups.

Q: Why is the price lower than pharmacy retail or other research sites?

A: Peptide.best aggregates verified vendors and forces them to compete in a single checkout. Vendors save on customer-acquisition cost; the savings pass to you. Every batch is still 3rd-party COA tested.

About Vanta Bio

Vanta Bio is one of the six verified vendor partners on Peptide.best. They maintain a 4.8-star average rating across all products and submit every batch to third-party HPLC analysis before it ships.

All Vanta Bio products on Peptide.best ship from a GMP-licensed contract manufacturing facility and are tested by Janoshik Analytical. Cold-chain shipping is included on temperature-sensitive products.