If you’ve looked at CJC-1295 you’ve seen it listed two ways — “with DAC” and “without DAC” (or “no DAC”) — usually at noticeably different prices. The two are the same base peptide; the difference is a single chemical modification with the abbreviation DAC, and it changes one property dramatically: how long the molecule persists in circulation. This explainer covers what CJC-1295 is, what DAC actually is at the molecular level, and what the published research shows the modification does.
What CJC-1295 is
CJC-1295 is a synthetic analog of growth hormone–releasing hormone (GHRH). Specifically, it’s built on the first 29 amino acids of GHRH — the fragment known as GRF(1-29), which is the shortest segment that retains the parent hormone’s activity. Native GRF(1-29) is fragile: enzymes in plasma, principally dipeptidyl peptidase-IV (DPP-IV), cleave it within minutes.
CJC-1295 addresses that fragility with four amino acid substitutions in the GRF(1-29) backbone, each chosen to blunt a route of enzymatic breakdown. The result is a GHRH analog that resists degradation far better than the unmodified fragment. This stabilized backbone is common to both versions of CJC-1295 — the “with DAC” and “without DAC” forms share it. The DAC modification is something added on top.
What DAC is
DAC stands for Drug Affinity Complex. It is a small chemical group — a lysine linker carrying a maleimido (maleimide) function — attached to the peptide. The maleimide group is the active part: it reacts selectively with a free thiol (–SH), and the most abundant available thiol in the bloodstream is Cys34 of serum albumin, the body’s most plentiful circulating protein.
When the peptide encounters albumin, the maleimide forms a covalent bond to that cysteine, effectively tethering the small peptide to a large, long-lived carrier protein. That is the entire mechanism: DAC is a molecular hook that latches the peptide onto albumin.
What the tether changes: half-life
Albumin circulates for a long time and is too large to be filtered out by the kidneys quickly. By binding to it, the peptide inherits that longevity — it is shielded from the rapid renal clearance and enzymatic degradation that would otherwise remove a small peptide within minutes.
The published pharmacology quantifies the difference. In a clinical pharmacology study in healthy adults, a single administration of CJC-1295 with DAC produced elevations in circulating growth hormone and insulin-like growth factor I (IGF-I) that persisted for several days, with an estimated half-life on the order of about a week (Teichman et al., 2006). A companion study reported that the secretion remained pulsatile rather than flattening into a continuous release (Ionescu et al., 2006), and later work in an animal model characterized the same GH/IGF-1 axis activation (Sackmann-Sala et al., 2009).
The “without DAC” form lacks the maleimide group entirely, so it never binds albumin. It retains the stabilized GRF(1-29) backbone but clears on a much shorter timescale — minutes rather than days. This version is the one often labeled “Mod GRF 1-29” in the research literature; functionally, “CJC-1295 without DAC” and “Mod GRF 1-29” refer to the same modified fragment.
Where it sits in the GHRH-analog family
CJC-1295 is one of several research compounds built on the GHRH template, and the comparison clarifies what DAC contributes:
- Sermorelin is GRF(1-29) itself — the unmodified 29-amino-acid fragment, short-acting.
- CJC-1295 without DAC adds the four stabilizing substitutions to that fragment.
- CJC-1295 with DAC adds, on top of those substitutions, the albumin-binding hook.
- Tesamorelin is a separate stabilized GHRH analog with a different modification strategy.
Read down that list and DAC’s role is isolated cleanly: it is the one feature responsible for the multi-day persistence, layered onto an already-stabilized backbone.
Frequently asked questions
What does DAC stand for in peptides?
DAC stands for Drug Affinity Complex — a chemical group (a lysine linker with a maleimide function) added to a peptide so that it binds covalently to serum albumin in the bloodstream, which extends how long the peptide persists.
What is the difference between CJC-1295 with DAC and without DAC?
Both share the same stabilized GRF(1-29) backbone. The “with DAC” form carries an additional maleimide group that bonds to albumin, giving it a half-life measured in days; the “without DAC” form lacks that group and clears within minutes.
Is CJC-1295 without DAC the same as Mod GRF 1-29?
Yes. “CJC-1295 without DAC” and “Mod GRF 1-29” are two names for the same modified GRF(1-29) fragment.
How long does CJC-1295 with DAC last?
Published research in healthy adults estimated a half-life on the order of about a week, with measurable effects on GH and IGF-I persisting for several days after a single administration (Teichman et al., 2006).
How does CJC-1295 relate to sermorelin?
Sermorelin is the unmodified GRF(1-29) fragment. CJC-1295 is the same fragment with stabilizing substitutions, and — in the DAC version — an added albumin-binding group.
References
- Teichman SL, 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. Journal of Clinical Endocrinology & Metabolism. 2006. PMID: 16352683.
- Ionescu M, et al. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. Journal of Clinical Endocrinology & Metabolism. 2006. PMID: 17018654.
- Sackmann-Sala L, et al. Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog. Growth Hormone & IGF Research. 2009. PMID: 19386527.
For research use only. The products and materials discussed are intended for laboratory research purposes and are not for human or veterinary use, diagnosis, or treatment. This article describes the chemical structure and published pharmacological research of a compound and does not constitute a claim of any effect in any individual.
