IGF-1 LR3: Reference Overview and Reconstitution Notes

IGF-1 LR3

What it is

IGF-1 LR3, also written Long R3 IGF-1, is a synthetic analog of insulin-like growth factor 1, a growth-factor peptide. It differs from native IGF-1 by an arginine substitution at position 3 and a 13-amino-acid N-terminal extension, changes that reduce its affinity for IGF binding proteins and extend how long it stays active.

Research context and categorization

IGF-1 LR3 is generally grouped as a growth factor, part of the insulin-like growth factor family and downstream of growth-hormone signaling. In laboratory settings it is commonly discussed in relation to cellular proliferation, protein synthesis, and muscle and tissue research, and it is investigated for its effects on cell differentiation and metabolic signaling in preclinical models. Its longer half-life relative to native IGF-1 is the main reason it is used as a research tool when sustained receptor activation is being studied. These uses are investigational observations from research models only. They are not confirmed or approved effects in humans, and the compound is not established as safe or effective for any therapeutic purpose.

Status

  • Regulatory status: Research-only. IGF-1 LR3 is not FDA-approved for any indication and is not permitted to be sold as a dietary supplement or a drug for human use. The FDA has treated compounded IGF-1 LR3 as ineligible for the usual compounding exemptions. It circulates as a research chemical intended for in-vitro laboratory work only.
  • Sport status: Prohibited under the WADA Prohibited List. IGF-1 and its analogs, including IGF-1 LR3, fall under class S2 (Peptide Hormones, Growth Factors, Related Substances, and Mimetics) and are prohibited at all times, both in and out of competition.

Reconstitution notes (general)

Reconstitution concentration is the milligrams of peptide in the vial divided by the millilitres of liquid added. For example, a 1 mg vial brought up with 1 mL of diluent gives 1 mg/mL, and the same vial with 2 mL gives 0.5 mg/mL. A reconstitution calculator is available at our reconstitution and blend calculators.

Dilution and handling notes (compound-specific)

IGF-1 LR3 ships as a lyophilized (freeze-dried) powder that is reconstituted before use, so the vial does need a diluent added. Vials are commonly sold in sizes such as 0.1 mg and 1 mg, and a frequent laboratory choice is enough liquid to reach roughly 1 mg/mL, though the exact volume is a matter of the working concentration desired rather than a fixed rule.

The compound-specific quirk is solubility. IGF-1 LR3 does not always dissolve cleanly in plain bacteriostatic water at neutral pH. It has a documented tendency to go cloudy, look incomplete, or leave a faintly hazy solution when put straight into neutral water. The practical reason is that this peptide dissolves far more reliably under mildly acidic conditions, which protonate surface residues and improve solubility. For that reason many laboratory protocols reconstitute IGF-1 LR3 in a dilute acidic vehicle first, such as dilute acetic acid water (on the order of 0.1 to 0.6 percent, pH near 3) or dilute hydrochloric acid, and only then, if a larger volume is wanted, dilute further with bacteriostatic water. If a solution stays cloudy in neutral water, that cloudiness is the signal that the solvent, not the powder, is the issue. Note that acetic-acid preparations tend to have a shorter usable window than bacteriostatic-water preparations because they lack the benzyl alcohol preservative.

Two further handling points. First, the peptide is sensitive to light and to oxidation, so working solutions and the powder alike should be kept out of light. Second, it is sensitive to mechanical stress: adding diluent slowly down the inner wall of the vial rather than directing it onto the powder cake, and swirling gently rather than shaking or vortexing, reduces foaming and aggregation. Repeated freeze-thaw cycling is also best avoided because it can shear the peptide and reduce potency.

Handling and storage

Store the reconstituted vial refrigerated at 2 to 8 degrees Celsius and keep it out of light. Wipe the rubber stopper with alcohol before each puncture. Label the vial with the mix date and observe the general reconstituted window of roughly four weeks under refrigeration. Discard any vial that turns cloudy (beyond an expected solvent haze), discolored, or shows floaters. Unreconstituted lyophilized powder is best kept frozen for long-term storage.

Related reading

Tools and supplies

For laboratory and research reference only. Educational content, not medical, dosing, injection, or therapeutic guidance, and not intended for human or animal use. Any research uses described are investigational and not confirmed or approved benefits. Confirm anything involving health with a licensed professional. References linked above.