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CJC-1295 DAC vs. No DAC (Mod GRF 1-29): Pharmacokinetics & Research Guide
In growth hormone secretagogue research, CJC-1295 is one of the most frequently studied synthetic analogs of Growth Hormone-Releasing Hormone (GHRH 1-29). However, substantial confusion exists regarding CJC-1295 with DAC (Drug Affinity Complex) versus CJC-1295 No DAC (correctly designated in scientific literature as Modified GRF 1-29). This guide examines the pharmacological differences, half-life mechanics, and biological implications of both analogs in laboratory research models.
At a Glance: DAC vs. No DAC Comparison
| Parameter | CJC-1295 with DAC | CJC-1295 No DAC (Mod GRF 1-29) |
|---|---|---|
| Chemical Modification | Tetrasubstituted GHRH(1-29) + Maleimidopropionic acid linker (DAC) | Tetrasubstituted GHRH(1-29) [D-Ala2, Gln8, Ala15, Leu27]-GRF(1-29)NH2 |
| Elimination Half-Life | 6 to 8 days (via bioconjugation to circulating albumin) | 30 minutes (mimics natural physiological GH pulses) |
| GH Release Pattern | Continuous, sustained GH & IGF-1 elevation (elevated basal trough) | Pulsatile, sharp peak release preserving natural circadian pituitary rhythm |
| Common Research Stacks | Stand-alone continuous GHRH exposure models | Synergistically co-administered with Ipamorelin or GHRP-2 |
What is the Drug Affinity Complex (DAC)?
The Drug Affinity Complex (DAC) is a maleimidopropionic acid moiety covalently attached to the C-terminal lysine of the peptide. Following administration in animal models, the maleimide group reacts specifically and irreversibly with the free thiol group on cysteine-34 of circulating serum albumin.
Because serum albumin has an extended half-life of approximately 19 to 20 days in circulation, the albumin-peptide bioconjugate is protected from enzymatic degradation by dipeptidyl peptidase-4 (DPP-4) and renal clearance. This extends the active circulating half-life of CJC-1295 from 30 minutes to over one week.
Why Mod GRF 1-29 (No DAC) is Preferred with Ipamorelin
In physiological endocrinology, the pituitary gland releases growth hormone in distinct, pulsatile spikes rather than a flat, constant trickle. Constant stimulation of pituitary somatotrophs can lead to receptor desensitization over prolonged periods.
For this reason, laboratory models investigating physiological pulsatility combine CJC-1295 No DAC (Mod GRF 1-29) with a selective growth hormone secretagogue receptor (GHSR) agonist such as Ipamorelin. When GHRH (via Mod GRF 1-29) and GHRP (via Ipamorelin) are co-administered, they produce a massive synergistic pulse that is up to 5 times larger than either compound alone, while returning to baseline within 2 to 3 hours.
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References & Scientific Literature
- Teichman SL, Neale A, Lawrence B, et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799-805. PMID 16352683.
- Jette L, Legault R, Titus L, et al. d-Ala2-CJC-1295, a synthetic GHRH analog with extended half-life through bioconjugation to human serum albumin. Endocrinology. 2005;146(7):3052-3058. PMID 15817669.