CJC-1295 DAC vs CJC-1295 No DAC: What the Drug Affinity Complex Changes

Q: What does DAC mean in CJC-1295 DAC?

Drug affinity complex. It denotes a maleimidopropionamide group carried on a lysine added at position 30, which reacts with the free thiol on cysteine 34 of serum albumin after administration to form a covalent conjugate . CJC-1295 No DAC is the same 29-residue chain without that lysine and without the conjugating group.

Q: Do the two forms act at different receptors?

No. Both act at the pituitary growth hormone-releasing hormone receptor, a class B1 G protein-coupled receptor cloned in 1993 that signals through Gs and cyclic AMP . The four amino acid substitutions both carry — D-alanine at 2, glutamine at 8, alanine at 15, leucine at 27 — are associated in the GHRH-analogue literature with resistance to enzymatic cleavage rather than with altered receptor selectivity . The difference between the two forms is pharmacokinetic.

Q: How long does each form persist in plasma?

For CJC-1295 DAC the estimated half-life in published human study was 5.8 to 8.1 days . For the unconjugated form the answer is that nobody has published a measurement. No pharmacokinetic study of it exists under that name, so its plasma half-life is an unmeasured quantity rather than a reported figure.

Q: Have the two forms been compared in the same study?

No, and no such comparison is possible on the present record, because one of the two has never been the subject of a published clinical trial. Human data attributed to CJC-1295 belongs to the conjugated form, and reading it across to the unconjugated form assumes precisely what the added group was designed to change.

Q: Is either form FDA approved?

Neither is approved for any indication. CJC-1295 DAC reached phase 2 and development stopped; no product containing the unconjugated analogue has been approved.

Q: Is albumin conjugation the same as the albumin binding used by incretin analogues?

No, and the distinction is one of kind rather than degree. The DAC group forms a covalent bond with cysteine 34 of albumin . Acylated incretin analogues bind albumin reversibly through a fatty acid, so the peptide detaches and reattaches continuously. A covalent conjugate does not.

Q: Did the long-acting form flatten the pulsatile pattern of growth hormone secretion?

No, which is not what a naive model of continuous stimulation would predict. In healthy men sampled every 20 minutes across an overnight window one week after a single administration, pulse frequency and magnitude were unaltered while basal trough concentrations rose 7.5-fold, mean concentrations rose 46% and IGF-1 rose 45% . It is a small mechanistic study in healthy young men at one sampling window.

Q: Does the unconjugated form have a CAS number?

Not one supplied by a public register. No register carries a separate record for it under this name, so there is no register-supplied CAS number, UNII or PubChem identifier. The four substitutions published for it are those recorded in the register entry for CJC-1295 itself, whose 30-residue chain is this sequence plus the lysine carrying the conjugating group. Registry numbers circulating in commercial listings for this material belong to other substances.

Two forms of one GHRH analogue backbone. One carries an albumin-conjugating group and has published human pharmacokinetics; the other has none.

By Elegance Peptides Editorial TeamUpdated September 22, 2026

This is the narrowest comparison in the library and, for that reason, one of the cleanest. The two materials share twenty-nine residues, four amino acid substitutions and one receptor. They differ in a single chemical group attached at one end — and that group changes the plasma behaviour of the molecule by roughly three orders of magnitude.

The evidence available for each differs just as sharply, and in the opposite direction from what the shared name suggests. The conjugated form has published human pharmacokinetics. The unconjugated form has no published clinical study at all under that name.

What they are

Property	CJC-1295 DAC	CJC-1295 No DAC
Development code	CJC-1295	Not established
Compound type	Synthetic modified peptide	Synthetic peptide analogue
Peptide family	Glucagon / secretin peptide superfamily (growth hormone-releasing hormone analogues)	Glucagon / secretin peptide superfamily (growth hormone-releasing hormone analogues)
Primary target	Growth hormone-releasing hormone receptor (GHRHR)	Growth hormone-releasing hormone receptor (GHRHR)
Secondary targets	Not established	Not established
Receptor family	Class B1 (secretin-like) G protein-coupled receptors	Class B1 (secretin-like) G protein-coupled receptors
Agonist / antagonist	Agonist at the GHRH receptor	Agonist at the GHRH receptor
Highest research phase	Phase 2 (terminated)	No clinical study identified under this name; preclinical, analytical-chemistry and anti-doping detection literature only
Regulatory status (United States)	Not approved. CJC-1295 has not been approved by the U.S. Food and Drug Administration for any indication.	Not approved. No product containing this analogue has been approved by the U.S. Food and Drug Administration for any indication.
Human trials published	Yes	No

Every value in this table is read from the two compounds’ own library entries when the site is built, so it cannot disagree with them. Nothing here ranks one compound against the other.

CJC-1295 DAC is a synthetic 30-residue analogue of human growth hormone-releasing hormone. Residues 1 to 29 are a tetrasubstituted form of human GHRH(1-29); residue 30 is an added lysine carrying a maleimidopropionamide group, which is what "DAC" — drug affinity complex — denotes. It is recorded in the FDA/NCATS Global Substance Registration System under UNII 62RC32V9N7 with CAS registry number 446262-90-4. It is not approved for any indication, and its clinical development reached phase 2 and stopped.

CJC-1295 No DAC, also listed as modified GRF(1-29), is the same 29-residue tetrasubstituted chain without the added lysine and without the conjugating group, terminating in a C-terminal amide. No public register carries a separate record for it under that name, so there is no register-supplied CAS number, UNII or PubChem identifier. It is not approved for any indication, and no clinical trial of it has been published under this name.

The four substitutions are identical in both and are the same four: D-alanine for L-alanine at position 2, glutamine for asparagine at 8, alanine for glycine at 15, and leucine for methionine at 27, read against human GHRH(1-29). The molecular weights differ by the mass of the added lysine and its conjugating group: 3,647.2 g/mol against 3,367.9 g/mol.

Receptor and mechanistic differences

At the receptor there is no difference worth claiming. Both act at the pituitary growth hormone-releasing hormone receptor, a class B1 G protein-coupled receptor cloned in 1993 that signals through Gs and cyclic AMP ^[2]. GHRH(1-29) is the minimum fragment of the native hormone that retains full activity at that receptor, and the four substitutions both molecules carry are the ones the GHRH-analogue literature associates with resistance to enzymatic cleavage rather than with altered receptor selectivity ^[4]. Neither form is described in the literature as having different receptor pharmacology from the other.

The difference is entirely pharmacokinetic, and it operates in two stages.

The first stage is shared. Native GHRH is cleared within minutes by dipeptidyl peptidase-4, which cleaves the molecule at the N-terminus; the position-2 substitution present in both forms is the modification shown in plasma-stability work to block that cleavage ^{[1, 3]}. So both molecules are protected against the enzyme that destroys the native hormone.

The second stage belongs to the DAC form alone. The maleimidopropionamide group reacts with the free thiol on cysteine 34 of serum albumin after administration, forming a covalent conjugate. The resulting molecule remains a GHRH receptor agonist but is cleared far more slowly than the unconjugated peptide, because it is now attached to a plasma protein with a residence time of weeks ^[5]. That is a covalent bond, not the reversible albumin binding used by the acylated incretin analogues elsewhere in this library — a distinction in kind, not degree.

Shared backbone: Both carry the same tetrasubstituted GHRH(1-29) chain: D-Ala2, Gln8, Ala15, Leu27 ^[4].
Receptor: Both act at the pituitary GHRH receptor, class B1, Gs-coupled ^[2].
The added group: DAC carries a lysine at position 30 bearing a maleimidopropionamide that conjugates covalently to cysteine 34 of serum albumin ^[5]. No DAC carries neither.
Reported half-life: DAC, estimated at 5.8 to 8.1 days in published human study ^[6]. No DAC, never measured in any published study.
Register identity: DAC — UNII 62RC32V9N7, CAS 446262-90-4. No DAC — no register record under this name.
Published clinical evidence: DAC — phase 1 and phase 2 ^{[6, 7, 8]}. No DAC — none.

What the research compares

No study has compared the two forms against each other in humans. There is no head-to-head trial, and there could not be one on the current record, because one of the two has never been the subject of a published clinical trial at all.

That asymmetry is the single most important thing on this page, and it is easy to miss because the two materials share a name. Published human data attributed to "CJC-1295" belongs to the conjugated form. Reading it across to the unconjugated form assumes exactly what the modification was designed to change.

What does exist is the biochemistry that separates them. The albumin-conjugation chemistry was characterised in a study showing that human GHRH(1-29)–albumin bioconjugates activate the GHRH receptor on the anterior pituitary, which established that conjugation does not abolish receptor activity ^[5]. And a substantial analytical-chemistry and anti-doping literature exists for both forms, because detecting them in biological samples is a live problem: methods for confirming CJC-1295 in equine plasma by liquid chromatography–tandem mass spectrometry ^[11], identification of CJC-1295 in an unknown pharmaceutical preparation ^[10], and a review of advances in detecting synthetic GHRH analogues ^[12].

That detection literature is worth noticing for a reason beyond its subject. It exists because both forms circulate as materials rather than as approved medicines, and the papers describing them are analytical rather than clinical.

What the human research shows

Human clinical research

Results from pharmaceutical clinical trials describe the investigational material and populations used in those studies and should not be interpreted as establishing the effects of research-grade materials offered for laboratory use.

CJC-1295 DAC — the published record

Ascending-amount trials in healthy adults. Two randomised, placebo-controlled, double-blind trials of 28 and 49 days in healthy participants aged 21 to 61, at two investigational sites. After a single administration, mean plasma growth hormone concentrations rose two- to tenfold for six days or more and mean plasma IGF-1 rose 1.5- to threefold for nine to eleven days, both graded with the amount administered. The estimated half-life of the compound was 5.8 to 8.1 days, and after repeated administration mean IGF-1 remained above baseline for up to 28 days. No serious adverse reactions were reported ^[6].

Secretion pattern in healthy men. In healthy men aged 20 to 40, growth hormone secretion was sampled every 20 minutes across an overnight 12-hour window before and one week after a single administration of 60 or 90 µg/kg. Overall secretion increased with pulsatility preserved: pulse frequency and magnitude were unaltered, while basal trough concentrations rose 7.5-fold (p < 0.0001), mean concentrations rose 46% (p < 0.01) and IGF-1 rose 45% (p < 0.001). No significant difference was observed between the two amounts administered ^[8].

That result is mechanistically specific and worth stating precisely: continuous receptor stimulation by a long-acting agonist did not flatten the pulsatile pattern of secretion, which is not what a naive model of tonic stimulation would predict ^[8].

Effect on circulating IGF-1 in a deficient population. Once-daily administration of the compound was reported to normalise IGF-1 concentrations in a study population characterised by deficiency ^[7].

Serum protein profiling. In eleven healthy young adult men, serum before and one week after a single administration was analysed by two-dimensional gel electrophoresis with mass spectrometric identification. Two spots decreased — an apolipoprotein A1 isoform and a transthyretin isoform — and three increased, and a linear relationship was found between one of them and IGF-1 concentrations. The authors state that the mechanisms linking these proteins to growth hormone and IGF-1 activity remain to be clarified ^[9].

Limitations across the DAC record. Small early-phase studies in healthy volunteers over 28 to 49 days, designed to characterise pharmacokinetics and safety rather than any clinical outcome; the pulsatility and proteomic studies involved tens of participants at a single timepoint. Development reached phase 2 and stopped, and a registered trial in a specific population was conducted without a published result establishing efficacy ^[13].

CJC-1295 No DAC — the absence of a record

There is no published clinical trial of the unconjugated analogue under this name. No pharmacokinetic study has been published for it, so the plasma half-life of the molecule is not a reported figure — it is an unmeasured quantity.

What can be said is narrower and rests on the biochemistry rather than on any trial. The position-2 substitution it carries is the one demonstrated to block dipeptidyl peptidase-4 cleavage of GHRH in plasma-stability work ^{[1, 3]}, so the molecule is expected to survive longer than the native hormone. How much longer has not been measured in any published study of the unconjugated form. Figures circulating for its duration are not traceable to a published clinical measurement.

The absence is not evidence of a short half-life or a long one. It is an absence, and this page reports it as one.

What the preclinical and in vitro research shows

In vitro research

The receptor work that underlies both molecules predates either. The human anterior pituitary GHRH receptor was cloned and expressed in 1993, establishing the class B1 G protein-coupled receptor that both forms act at ^[2]. Plasma-stability work in 1989 identified dipeptidyl peptidase-4 and trypsin-like enzymatic degradation as the routes by which native GHRH is cleared within minutes, which is what every substitution in both molecules is a response to ^[1]. Work on porcine kidney dipeptidyl peptidase IV then established how the enzyme cleaves GHRH analogues specifically ^[3], and the superactive-agonist literature characterised the substitutions that confer resistance ^[4].

The conjugation chemistry itself was characterised in bioconjugate work showing that human GHRH(1-29)–albumin conjugates activate the GHRH receptor on the anterior pituitary ^[5]. That is the in vitro result the DAC form depends on: without it, covalent attachment to a 66 kDa plasma protein would be a plausible way to abolish activity rather than to extend it.

No comparative in vitro characterisation of the two forms against each other has been published.

Research status of each

CJC-1295 DAC reached phase 2 and stopped. It is not approved for any indication, and its published human record consists of early-phase pharmacokinetic and pharmacodynamic studies in small numbers of participants ^{[6, 8, 7, 9]}.

CJC-1295 No DAC has no identified clinical study under that name. Its published literature is preclinical, analytical-chemistry and anti-doping detection work ^{[10, 12]}. It is not approved for any indication.

Neither material has an approved use. Where human studies exist, they studied pharmaceutical investigational material manufactured to a regulatory standard, administered under a registered protocol in a defined population under clinical supervision. None of that research is research into, or evidence about, research-grade material supplied for laboratory use.

Frequently Asked Questions

What does DAC mean in CJC-1295 DAC?

Drug affinity complex. It denotes a maleimidopropionamide group carried on a lysine added at position 30, which reacts with the free thiol on cysteine 34 of serum albumin after administration to form a covalent conjugate ^[5]. CJC-1295 No DAC is the same 29-residue chain without that lysine and without the conjugating group.

Do the two forms act at different receptors?

No. Both act at the pituitary growth hormone-releasing hormone receptor, a class B1 G protein-coupled receptor cloned in 1993 that signals through Gs and cyclic AMP ^[2]. The four amino acid substitutions both carry — D-alanine at 2, glutamine at 8, alanine at 15, leucine at 27 — are associated in the GHRH-analogue literature with resistance to enzymatic cleavage rather than with altered receptor selectivity ^[4]. The difference between the two forms is pharmacokinetic.

How long does each form persist in plasma?

For CJC-1295 DAC the estimated half-life in published human study was 5.8 to 8.1 days ^[6]. For the unconjugated form the answer is that nobody has published a measurement. No pharmacokinetic study of it exists under that name, so its plasma half-life is an unmeasured quantity rather than a reported figure.

Have the two forms been compared in the same study?

No, and no such comparison is possible on the present record, because one of the two has never been the subject of a published clinical trial. Human data attributed to CJC-1295 belongs to the conjugated form, and reading it across to the unconjugated form assumes precisely what the added group was designed to change.

Is either form FDA approved?

Neither is approved for any indication. CJC-1295 DAC reached phase 2 and development stopped; no product containing the unconjugated analogue has been approved.

Is albumin conjugation the same as the albumin binding used by incretin analogues?

No, and the distinction is one of kind rather than degree. The DAC group forms a covalent bond with cysteine 34 of albumin ^[5]. Acylated incretin analogues bind albumin reversibly through a fatty acid, so the peptide detaches and reattaches continuously. A covalent conjugate does not.

Did the long-acting form flatten the pulsatile pattern of growth hormone secretion?

No, which is not what a naive model of continuous stimulation would predict. In healthy men sampled every 20 minutes across an overnight window one week after a single administration, pulse frequency and magnitude were unaltered while basal trough concentrations rose 7.5-fold, mean concentrations rose 46% and IGF-1 rose 45% ^[8]. It is a small mechanistic study in healthy young men at one sampling window.

Does the unconjugated form have a CAS number?

Not one supplied by a public register. No register carries a separate record for it under this name, so there is no register-supplied CAS number, UNII or PubChem identifier. The four substitutions published for it are those recorded in the register entry for CJC-1295 itself, whose 30-residue chain is this sequence plus the lysine carrying the conjugating group. Registry numbers circulating in commercial listings for this material belong to other substances.

References

Dipeptidylpeptidase IV and trypsin-like enzymatic degradation of human growth hormone-releasing hormone in plasma The Journal of Clinical Investigation; 1989. PMID 2565342 doi:10.1172/JCI114049
Molecular cloning and expression of a human anterior pituitary receptor for growth hormone-releasing hormone Molecular Endocrinology; 1993. PMID 7680413 doi:10.1210/mend.7.1.7680413
Dipeptidyl peptidase IV (DPP-IV) from pig kidney cleaves analogs of bovine growth hormone-releasing factor (bGRF) modified at position 2 with Ser, Thr or Val. Extended DPP-IV substrate specificity? Biochimica et Biophysica Acta; 1993. PMID 8102071 doi:10.1016/0167-4838(93)90256-q
Synthesis and biological evaluation of superactive agonists of growth hormone-releasing hormone Proceedings of the National Academy of Sciences of the United States of America; 1995. PMID 7761415 doi:10.1073/pnas.92.11.4872
Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog Endocrinology; 2005. PMID 15817669 doi:10.1210/en.2004-1286
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 The Journal of Clinical Endocrinology and Metabolism; 2006. PMID 16352683 doi:10.1210/jc.2005-1536
Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse American Journal of Physiology. Endocrinology and Metabolism; 2006. PMID 16822960 doi:10.1152/ajpendo.00201.2006
Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog The Journal of Clinical Endocrinology and Metabolism; 2006. PMID 17018654 doi:10.1210/jc.2006-1702
Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects Growth Hormone & IGF Research; 2009. PMID 19386527 doi:10.1016/j.ghir.2009.03.001
Identification of CJC-1295, a growth-hormone-releasing peptide, in an unknown pharmaceutical preparation Drug Testing and Analysis; 2010. PMID 21204297 doi:10.1002/dta.233
A method for confirming CJC-1295 abuse in equine plasma samples by LC-MS/MS Drug Testing and Analysis; 2019. PMID 30938069 doi:10.1002/dta.2599
Advances in the detection of growth hormone releasing hormone synthetic analogs Drug Testing and Analysis; 2021. PMID 34665524 doi:10.1002/dta.3183
A Study to Evaluate CJC 1295 in HIV Patients With Visceral Obesity. NCT00267527

Every identifier above is resolved against PubMed, Crossref or ClinicalTrials.gov at build time, and the title returned by the register is compared with the title stored here. A page does not publish if a reference fails to resolve.

Research-Use Information

For in vitro research use only. This material is a laboratory reagent. It is not a drug, food, dietary supplement, or cosmetic and is not for human or veterinary use, including ingestion, injection, or any other administration. No information on this page describes or implies any effect in humans or animals. Sold only to researchers under our Terms of Sale.