CJC-1295 with DAC (drug affinity complex) is a modified analogue of Growth Hormone Releasing Hormone (GHRH 1-29) that incorporates a maleimide-lysine linker enabling covalent binding to circulating albumin after administration. This modification extends biological half-life from approximately 30 minutes (Mod GRF 1-29) to 6–8 days, fundamentally altering GH secretion kinetics compared to shorter-acting GHRH analogues.
The drug affinity complex (DAC) technology was developed by ConjuChem Biotechnologies. It attaches a reactive succinimidyl maleimide group to the lysine at position 29 (or a substituted lysine analogue). Once administered, this group reacts with the free thiol of Cysteine-34 on serum albumin, forming a stable thioether bond. Because albumin has a half-life of approximately 19 days and is not renally filtered, this dramatically prolongs peptide circulation.
The result is that CJC-1295 DAC causes sustained elevation of plasma GH and IGF-1 over days rather than the transient pulse seen with shorter analogues. This is pharmacologically distinct: rather than mimicking physiological pulsatile secretion, it maintains elevated GH output more continuously.
Teichman et al. (2006) conducted the pivotal Phase I/II study of CJC-1295 in healthy adults. Single subcutaneous injections of 30–60 µg/kg produced dose-dependent, sustained GH elevation with peak GH levels 2–6× above baseline maintained for up to 6 days. IGF-1 levels increased by 2–3-fold and remained elevated for 9–11 days. Repeat weekly dosing produced cumulative IGF-1 elevation. The compound was well tolerated across all doses in this study, with the primary adverse effects being transient injection site reactions and mild water retention-like symptoms at higher doses.
This dataset remains the most complete published human pharmacokinetic characterisation of any long-acting GHRH analogue in the research literature.
The sustained GH secretion pattern produced by CJC-1295 DAC has been termed a "GH bleed" in research literature — a continuous low-to-moderate GH output rather than discrete physiological pulses. This pharmacology has implications for receptor regulation: chronic stimulation of GHRH receptors on somatotroph cells can lead to partial desensitisation over time, and the absence of normal somatostatin-driven inter-pulse troughs alters the normal GH/IGF-1 axis feedback dynamics.
Research comparing DAC vs no-DAC protocols shows different downstream effects: continuous IGF-1 elevation may support sustained anabolic signalling, while pulsatile protocols may better preserve receptor sensitivity and more closely replicate physiological GH patterns.
CJC-1295 DAC's prolonged action makes it of interest in research models of GH deficiency where sustained IGF-1 normalisation is the endpoint. In preclinical GH-deficient rodent models, weekly dosing protocols with GHRH analogues demonstrate improvements in lean mass, bone density, and metabolic markers including reduced visceral adiposity.
Research into lipolysis mechanisms has examined whether CJC-1295 DAC-driven GH elevation activates hormone-sensitive lipase in adipocytes to a similar degree as pulsatile GH — an important question for metabolic disease models.
Due to its long action, CJC-1295 DAC is less commonly paired with short-acting GHRPs in research contexts (where peak plasma timing for synergy is less practical). However, combinations with ipamorelin administered on a different schedule have been explored to assess whether GHSR-1a stimulation adds incremental GH release on top of a sustained GHRH background.
