IGF-1 LR3
Quick summary
A long-acting IGF-1 analog with an arginine substitution and an extension at one end. Research focus: IGF-1 receptor signaling and cell culture media. This page leads with SRP's low-and-slow starting dose.
Overview
A long-acting IGF-1 analog with an arginine substitution and an extension at one end. These changes reduce binding to IGF-binding proteins, and it is used widely in cell culture.
Looking for research material? Simple Research Peptides lists IGF-1 LR3 (1 mg Vial) for laboratory research use.
Mechanism
An IGF-1 variant that IGF-binding proteins hold onto poorly, so more of it stays free to activate IGF-1 receptors.
Research areas
- IGF-1 receptor signaling
- cell culture media
Storage & reconstitution
Supplied as a freeze-dried (lyophilized) powder in a sealed vial. Unopened vials are generally kept cold and away from light. Labs usually reconstitute it with bacteriostatic or sterile water, letting the liquid run down the vial wall and swirling gently instead of shaking. The solution is then kept refrigerated.
Recommended starting dose (low and slow)
| Starting dose | 20 mcg once daily (assessment step; ranges all begin at 20 mcg). |
|---|---|
| Frequency | Reported schedules: daily, often post-training; 20–50mcg daily; Daily; Daily. |
| Reconstitution | Examples: 1 mg vial + 2 mL bacteriostatic water = 0.5 mg/mL; 1 mg vial + 3 mL water = 0.33 mg/mL; 1mg vial + 1mL acetic diluent (as listed). Different water volumes can be used; that only changes the draw volume, not the amount of peptide. storage note: Fragile molecule: refrigerate, avoid shaking, use within 2–4 weeks. |
Studied higher doses
Studies have used doses up to the amounts below. Higher doses can be dangerous. Whether a person can reach them safely depends on height, weight, activity level, training and pre-existing conditions. We recommend following the lower starting dose above, and contacting SRP with any questions.
| Highest amount reported in studies | Conflict: stop at 50 mcg per day, at 60 mcg, with some reports up to 80-100 mcg (advanced). Gains reportedly flatten above about 50-60 mcg. |
|---|---|
| Step-up schedules reported | Tiers: 20 mcg daily as an assessment dose, 20-40 mcg low range, 40-80 mcg moderate, 80-100 mcg high (side effects rise). It stresses glucose monitoring. |
Route and timing
Route: Subcutaneous injection after reconstitution is the route most often described in research protocols.
Timing: Pending - to be added by SRP
Cycle length and repeat
Pending - to be added by SRP
Half-life
Approximate, for Bobby's review: About 20 to 30 hours.
Side effects
Pending - to be added by SRP
Suggested bloodwork and monitoring
Draft, for Bobby's review: CBC and comprehensive metabolic panel (kidney and liver function, electrolytes) before starting and again after a few weeks; IGF-1, fasting glucose and HbA1c.
Cautions
Pending - to be added by SRP
Reconstitution calculator
Math aid only. It converts the numbers you enter; it is not dosing advice. For research use only. Prefilled with this page's vial size, reconstitution and low-and-slow starting dose where known; change any value.
Frequently asked questions
What is IGF-1 LR3 studied for?
In research it is studied for IGF-1 receptor signaling and cell culture media. An IGF-1 variant that IGF-binding proteins hold onto poorly, so more of it stays free to activate IGF-1 receptors.
How is IGF-1 LR3 given in research?
Subcutaneous injection after reconstitution is the route most often described in research protocols. See the dosing frequency block on this page for how often.
What amount should a researcher start with?
This page lists SRP's low-and-slow starting dose in the Recommended starting dose section. Higher amounts that appear in studies are listed separately with their safety context. Start with the lower dose and contact SRP with any questions.
Related peptides
Last updated: October 19, 2026