Source comparison
CJC-1295 Variants: DAC vs Non-DAC Pharmacokinetics
The half-life difference between CJC-1295 variants stems from one structural modification: the presence or absence of the Drug Affinity Complex. CJC-1295 with DAC is tetrasubstituted GHRH(1-29) with four maleimidoproprionic acid-lysine groups attached at posit
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- The half-life difference between CJC-1295 variants stems from one structural modification: the presence or absence of the Drug Affinity Complex. CJC-1295 with DAC is tetrasubstituted GHRH(1-29) with four maleimidoproprionic acid-lysine groups attached at positions 8, 15, 21, and 27. These lysine arms bind covalently to serum albumin. The most abundant plasma protein. Creating a conjugate that cannot be filtered through the kidneys or degraded by circulating proteases. Modified GRF(1-29) (the non-DAC version) contains amino acid substitutions at positions 2, 8, 15, and 27 to resist DPP-4 cleavage, but without albumin binding, it still clears from plasma within 30 minutes.
- A 2006 phase I study published in the Journal of Clinical Endocrinology & Metabolism measured CJC-1295 with DAC concentrations over 28 days following a single subcutaneous injection. Peak plasma levels occurred at 24–72 hours post-injection, with detectable concentrations persisting beyond 14 days. Growth hormone secretion remained elevated for 6+ days, returning to baseline only after the peptide fully dissociated from albumin. The same study confirmed DPP-4 resistance through enzymatic assays. Albumin-bound CJC-1295 showed no measurable degradation after 24-hour incubation with DPP-4, while unbound GHRH(1-29) was completely cleaved within 10 minutes.
- What's the half-life of CJC-1295 without DAC in practical terms? Plasma half-life is under 30 minutes, but biological half-life. The duration of elevated GH secretion. Extends to approximately 2–3 hours due to receptor binding at the pituitary. This is why Modified GRF(1-29) is typically dosed 2–3 times daily, timed to coincide with natural GH pulse windows (upon waking, post-training, before sleep). Researchers aiming to replicate physiological GH pulsatility prefer the non-DAC variant precisely because it doesn't create sustained supraphysiological elevation across multiple days.