CJC-1295 With DAC vs Without DAC: Same Receptor, Different Clock
By Peptura Research Team/22 May 2026/8 min read
Two Forms, One Molecule
CJC-1295 comes in two research forms with very different pharmacokinetic profiles. The 'without DAC' variant is a modified GHRH(1-29) analogue whose circulating half-life is measured in tens of minutes, giving a pulsatile growth hormone research model. The 'with DAC' variant carries a Drug Affinity Complex moiety that bonds covalently to circulating albumin, stretching the half-life to several days and producing a continuous GH elevation model. Both share the same core GHRH receptor agonism, but the kinetic split carries real experimental weight.
Peptura supplies both CJC-1295 with DAC and CJC-1295 without DAC as research-grade lyophilised powder.
Without DAC: Modified GHRH(1-29)
The 'no DAC' form is a modified GHRH(1-29) sequence carrying four amino acid substitutions chosen to resist enzymatic degradation by dipeptidyl peptidase IV (DPP-IV) and other serum proteases. Those substitutions are usually given as D-Ala at position 2, Gln at position 8, Ala at position 15, and Leu at position 27. They push the serum half-life from the minutes range of native GHRH out to around 30 minutes in research models, still brief enough to keep a pulsatile signalling pattern at the GHRH receptor when dosed intermittently.
With DAC: The Drug Affinity Complex
The 'with DAC' form appends a maleimidopropionic acid lysine moiety at the C-terminus of the modified GHRH(1-29) sequence. The maleimide group is reactive toward free cysteine thiols, so on injection it forms a covalent thioether bond with the free cysteine-34 residue of circulating serum albumin. That albumin conjugate is too large for renal filtration and shielded from the proteolytic clearance that would otherwise strip the peptide away fast. This albumin tethering is the entire pharmacokinetic difference between the two forms.
Teichman and colleagues published the first human pharmacokinetic data on CJC-1295 with DAC in the Journal of Clinical Endocrinology and Metabolism in 2005, reporting an estimated half-life of 5.8 to 8.1 days after subcutaneous administration in healthy adults, with sustained GH and IGF-1 elevation for up to 28 days after multiple doses. That is roughly a 200-fold extension of half-life over the no-DAC variant.
The Receptor Side Is Identical
Both variants bind the GHRH receptor on pituitary somatotrophs and drive growth hormone synthesis and release through the same cAMP-mediated cascade. Receptor pharmacology is not what separates them. The only true differentiator is how long the receptor is engaged: short pulses with the no-DAC form, a continuous bathing of the receptor with the DAC form.
Continuous Versus Pulsatile Models
That kinetic split yields fundamentally different research models. CJC-1295 without DAC, dosed in a typical protocol, produces discrete GH pulses with a return to baseline between doses, mirroring the body's natural pulsatile secretion and fitting questions where the pulsatile architecture of GH signalling matters.
CJC-1295 with DAC instead lifts trough GH levels continuously while preserving pulsatile peaks. Ionescu and Frohman reported in the Journal of Clinical Endocrinology and Metabolism in 2006 that pulsatile GH secretion survived CJC-1295 with DAC administration, the main effect being a 7.5-fold rise in trough, basal GH rather than any disruption of pulse architecture. That matters: chronic-elevation studies often assume pulsatility is lost, but the published data suggest basal and pulsatile contributions can be examined at the same time.
Research Applications
Reach for the no-DAC form when the question calls for preserved physiological pulsatility, controlled timing of GH exposure, or modelling of natural GHRH dynamics. Reach for the DAC form for chronic-exposure studies, less-frequent dosing, or work where sustained IGF-1 elevation is the desired output. Both are commonly paired with ghrelin receptor agonists such as Ipamorelin, where dual-pathway activation adds to GH release. The CJC-1295 vs Ipamorelin comparison covers that combined-pathway model, and the Tesamorelin vs CJC-1295 GH secretagogue comparison sets out alternative GH-releasing peptide tools.
Laboratory Handling
Both variants come as lyophilised powder. Store at -20°C before reconstitution. Reconstitute with bacteriostatic water by running the diluent slowly down the inner wall of the vial and swirling gently. Never shake. Keep the reconstituted solution at 2-8°C and use within four weeks. Do not combine the two forms in one vial unless a protocol specifically calls for it, since their very different kinetics complicate dose-response interpretation.
Sourcing in the UK
Peptura supplies research-grade CJC-1295 with DAC and CJC-1295 without DAC as lyophilised powder with full third-party HPLC documentation published on the product page. Same-day UK dispatch on orders placed before 2pm GMT, free Royal Mail Tracked shipping over £45. For in-vitro laboratory research use only, not for human consumption.
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Disclaimer: This article is for research and educational purposes only. All information provided is not intended as medical advice. Peptura products are not for human consumption and are sold strictly for laboratory research use only.