IGF-1 LR3 Half-Life Calculator
IGF-1 LR3 is a modified form of insulin-like growth factor 1, engineered so that it evades the binding proteins that normally control native IGF-1. That single change is why its half-life is measured in hours rather than minutes.
Half-life 25 hours · peaks at 2 hours
Every 24 hours.
Half-life
Left at next dose
IGF-1 LR3 · once daily · levels plateau after ~5.2 days
Steady-state peak
2.03 mg
Steady-state trough
1.1 mg
Accumulation
2.1×
At once daily, each dose lands before the previous one has cleared, so levels stack to about 2.1× a single dose before plateauing — roughly 5.2 days in. After the last dose it takes about 5.2 days to clear.
This is a modelled estimate of relative levels from published half-life and time-to-peak figures — not a measured blood concentration. Individual pharmacokinetics vary.
Based on a published IGF-1 LR3 half-life of about 25 hours. The chart models RELATIVE levels from a unit dose — enter your own figures to see the shape. It is not a dose recommendation.
Never do this math twice.
The Pep AI app remembers your vials and doses, shows an interactive syringe you draw to, counts down the doses left in each vial, and reminds you when it's time. Free on iOS and Android.
What a 25 hours half-life means in practice
A half-life of 25 hours against once daily dosing means each dose lands before the previous one has gone. That changes the curve in three ways:
1. One half-life
Half the dose is gone after 25 hours. After two half-lives 25% remains, after three 12.5%.
2. What's left at the next dose
Dosing once daily means the next dose lands 24 hours later, with about 51% of the previous one still present.
3. Accumulation and plateau
Those leftovers stack until intake matches elimination — about 2.1× a single dose, reached after roughly 5.2 days (five half-lives).
Worked example
IGF-1 LR3 has a half-life of 25 hours. Dosing once daily, the next dose arrives 24 hours later with about 51% of the previous one still on board. Levels therefore stack to roughly 2.1× a single dose before plateauing, which takes about 5.2 days — and after a final dose it takes about the same again to clear.
Escaping the binding proteins
Native IGF-1 circulates almost entirely bound to a family of binding proteins that control how much is free and active at any moment, and free IGF-1 has a half-life of minutes. IGF-1 LR3 carries substitutions and an extension that dramatically reduce that binding, so far more of it stays free — and free means both active and long-lived.
That is the point of the modification and also the reason it is a substantively different proposition from the native hormone. The binding protein system is a regulatory mechanism, and bypassing it removes the control layer rather than merely increasing the signal. IGF-1 LR3 has no approval for human use and is prohibited in competitive sport.
Frequently asked questions
This calculator is provided for informational and educational purposes only and is not medical advice. Always confirm dosing with a qualified healthcare professional and double-check your own measurements before administering anything.
Built by the Pep AI team.