IGF-1 LR3
IGF-1 LR3 is a research reference compound. Listed for research and educational reference only.
| Also known as | Modified Growth Factor Analog, Research Chemical Only |
|---|---|
| Evidence level | Limited Research |
| Regulatory status | Research-only |
| Updated | 2026-10-27 |
IGF-1 LR3 is a laboratory-made analog of insulin-like growth factor 1, a signaling protein mammals produce naturally, modified with an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. It is supplied only as a research reference material.
About this compound
IGF-1 LR3 is a man-made, long-lasting version of insulin-like growth factor 1, a natural protein. It exists only as a laboratory research reagent and is not approved by the FDA.
Hardware this article assumes
The reconstitution workflow below uses our reusable pen, a 3 ml glass cartridge, and a screw-on pen needle. Two fit details matter before any reconstitution, and they are often missed on first setup.
- Cartridge stopper: Our pens take standard 3 ml (300-unit) glass cartridges with the 11 mm long plunger (stopper), the cartridge we sell. 3 ml cartridges are also made with a shorter, about 8 mm plunger, and a pen is built for one height, so check that a cartridge from another source has the 11 mm long plunger before loading it; the glass looks identical from the outside.
- Pen needles: our pens accept universal 28G–33G screw-on pen needles, the same format used across most research-grade hardware.
- Compatibility scope: this article covers only Preppin Peppers hardware. Fit with third-party pens and cartridges has not been tested in our lab.
All of our reusable peptide pens (V1, V2, V3 and Gansulin) are compared on one page.
What it is
IGF-1 LR3 (also written Long R3 IGF-1) is a laboratory-made analog of insulin-like growth factor 1, a signaling protein mammals produce naturally. Both forms are built from a chain of amino acids, and the name itself describes the two modifications that distinguish the laboratory variant:
- Position 3 swap (the “R3”): the third amino acid in the chain is replaced with arginine.
- N-terminal extension (the “Long”): 13 extra amino acids are added to one end of the chain.
Together these changes weaken its grip on IGF-binding proteins in the bloodstream and lengthen the time it remains active compared with the natural hormone. It is supplied as a research-only reference material.
Research context and categorization
IGF-1 LR3 is a synthetic analog of insulin-like growth factor 1, classified as a research-use growth factor. It appears in peer-reviewed laboratory research literature only. This article covers IGF-1 LR3 specifically; other research peptides are documented separately.
How researchers categorize it
- Protein family: Insulin-like growth factor (IGF) family; structurally related to insulin.
- Upstream signaling: Investigated alongside growth hormone receptor pathways.
- Compound class: Long-acting recombinant analog of native IGF-1.
- Use setting: In vitro cell culture and controlled laboratory work.
- Regulatory status: Research chemical with no approved application.
Active research areas
- Cell proliferation, growth, and differentiation
- Protein synthesis and turnover pathways
- Skeletal muscle and connective tissue development models
- Cellular energy metabolism and signaling crosstalk
Why the "LR3" modification matters
The LR3 structural change extends the molecule's active window relative to native IGF-1, which is cleared quickly by standard cellular mechanisms. The modified analog lets researchers track sustained responses across longer time windows without repeated intervention, which is the principal reason it is selected over the native form in extended-duration studies.
Key point: IGF-1 LR3 is a research-only growth factor with an extended active window, intended for in vitro and controlled lab studies. It is not approved for use in people and has no established medical application.
Status
Regulatory
IGF-1 LR3 is supplied for research use only. It has not been evaluated or approved by the U.S. Food and Drug Administration for any indication, and it may not be marketed or sold as a dietary supplement or drug. The FDA has stated that compounded IGF-1 LR3 does not qualify for the usual pharmacy compounding exceptions. It is offered as a research chemical for in-vitro laboratory work (test-tube and cell-culture settings) only.
Sport (anti-doping)
IGF-1 LR3 is prohibited under the WADA Prohibited List - the anti-doping rules that govern elite sport worldwide. It falls under class S2: Peptide Hormones, Growth Factors, Related Substances, and Mimetics. It is banned at all times, both in-competition and out-of-competition, for athletes subject to WADA or WADA-aligned anti-doping programs.
Reconstitution notes (general)
Reconstitution concentration describes how much lyophilized powder ends up in a set volume of diluent. Divide the milligrams of peptide by the milliliters added. A 1 mg vial with 1 mL gives 1 mg/mL; the same vial with 2 mL gives 0.5 mg/mL. Use the peptide calculator for other vial sizes.
why does my GHK-Cu vial turn from blue to clear? The blue color comes from the copper(II) coordination complex. Reduction of the copper, shifts in pH, warmth, or prolonged storage can bleach the solution. A color shift is a useful visual cue but not a standalone purity test.
does benzyl alcohol affect peptide stability in solution? Benzyl alcohol is the preservative in bacteriostatic water and works with most peptides at typical working concentrations, though some copper-peptide complexes are sensitive. Always follow the specific peptide's documented solubility and storage guidance.
Dilution and handling notes (compound-specific)
IGF-1 LR3 arrives as a freeze-dried powder (the technical word is lyophilized). Before lab use, you add liquid to turn it back into a solution. Vials commonly come in sizes such as 0.1 mg and 1 mg. A common lab approach is to add enough liquid to reach roughly 1 mg/mL, though the exact amount depends on what working concentration you need.
A common lab approach is to add enough liquid to reach roughly 1 mg/mL , though the exact amount depends on what working concentration you need.
Solubility and Acidic Reconstitution
One important quirk with this compound is solubility, which means how well the powder dissolves. IGF-1 LR3 does not always dissolve cleanly in plain bacteriostatic water (water that contains a small amount of preservative to keep it from spoiling). In neutral water it can turn cloudy, look only partly dissolved, or leave a faint haze.
The reason is that this peptide dissolves far more reliably in mildly acidic liquid. Acidity is measured on a scale called pH, which runs from 0 to 14. A pH of 7 is neutral. Lower numbers mean more acidic. A mildly acidic solution puts a tiny electric charge on the outer surface of the molecule, which helps it dissolve.
Because of this, many lab protocols first mix IGF-1 LR3 in a dilute acidic liquid, such as weak acetic acid water (imagine a very faint vinegar-like solution, roughly 0.1 to 0.6 percent acid, at a pH near 3) or dilute hydrochloric acid. Once the powder has dissolved, researchers can add more bacteriostatic water if a larger total volume is needed.
If the solution stays cloudy in plain water, that is a sign the liquid is the problem, not the powder. Note that solutions made with acetic acid tend to have a shorter useful life than those made with bacteriostatic water, because acetic acid does not contain the same preservative that keeps bacteriostatic water fresh longer.
Handling Sensitivity
Researchers should follow several key handling steps:
- Sensitivity to light and oxidation: This peptide can break down when exposed to light or air (a process called oxidation). Keep both the powder and any working solution away from light.
- Sensitivity to mechanical stress: When adding liquid to the vial, let it run slowly down the inside wall rather than squirting it directly onto the powder. Gently swirl the vial instead of shaking it or using a fast mixer. This reduces foaming and clumping.
- Freeze-thaw cycling: Avoid freezing and thawing the solution more than once. Repeated freeze-thaw cycles can damage the peptide and lower its quality.
Handling and storage
Clean technique and consistent temperatures protect the working vial and help you recognize a compromised sample before next access.
Mixed vials
- Refrigerate at 2-8 degrees C (about 36-46 degrees F), protected from light.
- Wipe the stopper with isopropyl alcohol before each access.
- Label the vial with the mix date and use within roughly four weeks refrigerated.
- Discard if the solution clouds beyond a mild solvent haze, changes color (for example a blue-tinted solution shifting toward clear or colorless), or shows floating particles.
- Bacteriostatic diluents containing benzyl alcohol do not replace refrigeration; the same four-week working window applies.
Lyophilized powder
- Store unmixed vials in the freezer for long-term stability.
- Bring the vial to room temperature before opening to limit condensation on the stopper.
Frequently asked questions
What makes IGF-1 LR3 different from natural IGF-1?
Two structural changes , an arginine substitution at position 3 and a 13-amino-acid N-terminal extension , reduce IGF-binding-protein affinity, extending the compound's active window in cell and tissue lab studies.
How do you reconstitute IGF-1 LR3 for laboratory use?
Add bacteriostatic water to the lyophilized powder; divide the vial's mg content by the mL of diluent added to get concentration (e.g., 1 mg ÷ 1 mL = 1 mg/mL). Use a peptide calculator to confirm volumes before use.
What is the regulatory and sport status of IGF-1 LR3?
It is a research chemical for in-vitro use only. It is prohibited at all times under WADA Prohibited List class S2. Check applicable local regulations.
What the research community gets wrong about IGF-1 LR3 handling
IGF-1 LR3 trips researchers up at the reconstitution step more than almost any peptide on the bench. Most "bad vial" reports we hear trace back to workflow mistakes, not the powder itself. Here are the handling errors that show up most often.
- Reaching for plain bacteriostatic water first. IGF-1 LR3 often stays cloudy in plain water and clears far more reliably when a mildly acidic solvent is used first, with more diluent added afterward. Benzyl alcohol in bacteriostatic water is a preservative, not a stability enhancer, so an acid-made solution has a shorter useful window.
- Throwing out a vial too soon. A faint haze after adding solvent does not mean a bad vial. In the right acidic solvent it finishes dissolving with slow, gentle swirling and patience. Discard for a strong cloud, a persistent color change, or floating particulates — not a brief haze. Color shifts in unrelated peptides, like a copper-peptide vial going blue to clear, are usually a pH or solvent story.
- Shaking to speed things up. Fast shaking foams the liquid, and proteins tend to clump at the air-to-liquid surface. Let the solvent run down the inner glass wall and swirl slowly instead.
- Grabbing a cartridge with the wrong plunger height off the shelf. 3 ml glass cartridges come in two stopper formats. Our pens take standard 3 ml (300-unit) glass cartridges with the 11 mm long plunger (stopper), the cartridge we sell. 3 ml cartridges are also made with a shorter, about 8 mm plunger, and a pen is built for one height, so check that a cartridge from another source has the 11 mm long plunger before loading it; the glass looks identical from the outside. No competitor publishes this distinction, so researchers blame the pen when the cartridge is the mismatch.
- Assuming any pen needle will do. Our hardware takes universal 28G–33G screw-on pen needles. Off-spec or non-screw mounts can thread on loosely, leak at the seal, or bend the cannula when the cartridge is loaded.
- Underrating light and freeze-thaw. Room light or refreezing leftover solution breaks the peptide down faster than expected. Keep it dark, keep it cold, and avoid repeat freeze-thaw cycles.
From our bench: when we pressure-test our pens and cartridges with practice solutions, the cloudy-then-clear pattern researchers describe matches what we see. The fluid clears once the solvent chemistry is right, not by mixing harder, and letting diluent slide down the inner wall with a slow swirl gives a cleaner draw through the pen than any quick shake.
Sources
- UniProtKB P05019: Insulin-like growth factor 1 (IGF1, Homo sapiens), UniProt release 2026-03
- Dunaiski et al., J Endocrinol 1997: Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs
- Pell et al., Prog Growth Factor Res 1995: Further characterisation of an IGF-I enhancing antibody: actions on IGF-I-induced hypoglycaemia and interaction with the analogue LR3IGF-I
- Dunshea et al., Br J Nutr 2002: Insulin-like growth factor-I and analogues increase growth in artificially-reared neonatal pigs
✔ Reviewed by Bryan Le, PharmD, RPh
Bryan is a licensed pharmacist (Doctor of Pharmacy, Registered Pharmacist). Reconstituting lyophilized preparations is core pharmacy practice, so he reviews The Lab’s content for technical accuracy and to keep it within a research-and-education scope, with no medical or dosing advice. View profile on LinkedIn.
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For research and educational reference only. Not for human or veterinary use.