CJC-1295 (DAC) Half-Life Calculator
CJC-1295 exists in two versions with half-lives four orders of magnitude apart, and they are constantly confused. This page models the DAC version, whose albumin-binding modification extends its half-life from minutes to days.
Half-life 7 days · peaks at 1.3 hours
Every 7 days.
Half-life
Left at next dose
CJC-1295 (DAC) · once weekly · levels plateau after ~35 days
Steady-state peak
1.96 mg
Steady-state trough
0.97 mg
Accumulation
2×
At once weekly, each dose lands before the previous one has cleared, so levels stack to about 2× a single dose before plateauing — roughly 35 days in. After the last dose it takes about 35 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 CJC-1295 (DAC) half-life of about 7 days. The chart models RELATIVE levels from a unit dose — enter your own figures to see the shape. It is not a dose recommendation.
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What a 7 days half-life means in practice
A half-life of 7 days against once a week 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 7 days. After two half-lives 25% remains, after three 12.5%.
2. What's left at the next dose
Dosing once a week means the next dose lands 7 days later, with about 50% of the previous one still present.
3. Accumulation and plateau
Those leftovers stack until intake matches elimination — about 2× a single dose, reached after roughly 35 days (five half-lives).
Worked example
CJC-1295 (DAC) has a half-life of 7 days. Dosing once a week, the next dose arrives 7 days later with about 50% of the previous one still on board. Levels therefore stack to roughly 2× a single dose before plateauing, which takes about 35 days — and after a final dose it takes about the same again to clear.
DAC and no-DAC are not the same compound
CJC-1295 is a growth-hormone-releasing hormone analogue. The DAC — Drug Affinity Complex — is a chemical group that binds covalently to albumin in the bloodstream, making the whole assembly too large for the kidney to filter. That single modification takes the half-life from minutes to roughly a week.
The version without DAC, often sold as modified GRF (1-29), lacks that group entirely and clears in minutes. The two are routinely both called 'CJC-1295', which produces genuinely contradictory advice about intervals — one supports weekly administration and the other cannot possibly. Checking which version a source means is not pedantry; it is the difference between a curve that accumulates and one that does not exist between administrations.
Because the DAC version's half-life exceeds most dosing intervals, it accumulates substantially and takes weeks to clear. See how accumulation and steady state work for what that implies.
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.