September 20, 2026
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Search for CJC-1295 and you’ll immediately encounter two versions: one with DAC and one without. The naming makes it sound like a minor manufacturing variant, the kind of detail that wouldn’t change much in practice.
It changes almost everything. The two versions have half-lives that differ by a factor of roughly 300, and that single property determines which research questions each one can actually address.
DAC stands for Drug Affinity Complex. It’s a reactive chemical group attached to the peptide that allows it to bind covalently to serum albumin, an abundant protein circulating in blood.
Once bound to albumin, the peptide is effectively shielded from the enzymes that would otherwise clear it rapidly. It stays in circulation, remaining available to interact with GHRH receptors over an extended period. That’s the entire function of the DAC modification: it converts a short-acting molecule into a long-acting one without changing the receptor-binding portion.
Both versions are built on the same base molecule, a 29-amino-acid analog of growth hormone-releasing hormone (GHRH). The native GHRH(1-29) sequence has been modified at four positions, 2, 8, 15, and 27, replacing residues that would normally be vulnerable to cleavage by the enzyme dipeptidyl peptidase-IV (DPP-IV). Complete molecular data is on the CJC-1295 product page.
Those four substitutions give the analog greater stability than an unmodified GHRH fragment regardless of which version you’re working with. The DAC modification is an additional layer on top of that baseline stability, not a replacement for it.
The DAC version’s albumin binding produces a half-life measured in days, commonly cited as around a week. That extended presence means GHRH receptors experience sustained, continuous stimulation rather than brief intermittent signals.
For research purposes, this is useful when the question involves cumulative downstream effects, prolonged IGF-1 elevation being the most commonly studied example. If a study needs to observe what happens under sustained receptor activation over days, the DAC version is the tool designed for that.
The no-DAC version, frequently called Modified GRF (1-29) or Mod GRF, clears in approximately 30 minutes. That’s a dramatically shorter window, and it’s closer to the kinetics of natural GHRH, which is cleared within minutes of release. This version appears in the CJC-1295/Ipamorelin blend, paired at a 1:1 ratio with a ghrelin receptor agonist.
| With DAC | Without DAC | |
| Half-life | Approximately 1 week | Approximately 30 minutes |
| Albumin binding | Yes, covalent | No |
| Release pattern studied | Sustained, continuous | Pulsatile |
| Also called | CJC-1295 DAC | Modified GRF (1-29), Mod GRF |
| Common research pairing | Studied alone | Frequently paired with Ipamorelin |
This is the concept that makes the DAC distinction genuinely important rather than just a technical footnote.
Growth hormone isn’t released continuously in the body. It comes in pulses, with the largest typically occurring during deep sleep, separated by periods of low secretion. That pulsatile pattern isn’t incidental, it appears to be part of how the signal is interpreted physiologically.
The no-DAC version preserves that pulsatile character. Its short half-life means it produces a burst of receptor activation that then clears, allowing the natural rhythm to continue. The DAC version, by design, does the opposite: it maintains continuous activation, which is valuable for studying sustained-exposure effects but doesn’t replicate the natural pattern.
Neither approach is inherently superior. They answer different questions, and choosing between them without understanding that distinction is how research designs end up mismatched to their own objectives.
The no-DAC version’s short half-life is exactly why it’s the version paired with Ipamorelin rather than the DAC version. Ipamorelin acts on the ghrelin receptor, a completely separate pathway from the GHRH receptor CJC-1295 targets. Pairing two mechanistically independent compounds that both produce short, pulsatile activity allows researchers to study additive release while preserving the natural rhythm. See the Ipamorelin product page for more on its receptor selectivity.
It’s worth spending a moment on the base modifications, since they’re often confused with the DAC modification itself.
Native GHRH is broken down primarily by dipeptidyl peptidase-IV, an enzyme that cleaves peptides at specific recognition points. The four amino acid substitutions in CJC-1295’s backbone, at positions 2, 8, 15, and 27, replace the residues that enzyme recognizes. This is a form of stabilization, but a fundamentally different one from what DAC provides.
The substitutions make the molecule harder to break down chemically. DAC keeps the molecule sequestered on albumin so it isn’t exposed to breakdown in the first place. That’s why the no-DAC version still clears in about 30 minutes despite having those substitutions: they slow degradation, but nothing is holding the molecule in circulation.
Both versions are supplied as lyophilized powders that dissolve readily in water, typically reconstituted with bacteriostatic water for laboratory use. Store refrigerated at 2 to 8 degrees Celsius once reconstituted, with unreconstituted vials kept cool and dry.
Standard peptide handling practice applies: aliquot into working volumes rather than drawing repeatedly from a single vial, and minimize freeze-thaw cycles. Degradation affects data reliability, and it isn’t always visible on inspection, which is why documented purity at the point of purchase provides a meaningful baseline.
If the research question concerns sustained receptor activation and its cumulative downstream effects, the DAC version is the appropriate choice. If it concerns pulsatile signaling, natural release patterns, or combination protocols with a ghrelin receptor agonist, the no-DAC version is the match. Both versions are supplied as lyophilized powders requiring reconstitution with bacteriostatic water and refrigerated storage, and both are available through Peptides Vital with independent HPLC and mass spectrometry verification for every batch.
Which version of CJC-1295 lasts longer?
The DAC version, with a half-life of roughly one week compared to about 30 minutes for the no-DAC version.
What does DAC stand for?
Drug Affinity Complex, the chemical group that enables covalent binding to serum albumin and produces the extended half-life.
Why is no-DAC used in the Ipamorelin blend?
Its short half-life preserves a pulsatile release pattern, which pairs naturally with Ipamorelin’s own short-acting, receptor-selective activity.
Is one version better than the other?
Neither is universally better. They suit different research questions depending on whether sustained or pulsatile receptor activation is being studied.
What is Modified GRF (1-29)?
It’s another name for the no-DAC version of CJC-1295, sometimes shortened to Mod GRF.
All peptides referenced are sold by Peptides Vital strictly for laboratory and scientific research. Nothing in this article is intended as guidance for human use.
