what is the difference
CJC-1295 vs CJC-1295 with DAC
The same base peptide sold as two products, separated by a linker that decides how long it stays in blood and which one has a human record.
CJC-1295 is growth hormone releasing hormone 1-29 with four amino acid substitutions that slow the enzymes clearing it. That base peptide is sold in two forms. One is the peptide on its own, marketed as CJC-1295 without DAC or as Mod GRF 1-29. The other carries a Drug Affinity Complex, a linker that bonds the peptide to albumin in blood so it is carried around instead of cleared quickly.
So the difference between the two products is a linker, and everything else about them is identical. What follows from it is not: the version carrying the linker has three published human papers and a registered phase 2 trial, and the version without it has neither.
Not medical advice
This page reports what has been documented about a compound. It is not medical advice, not a diagnosis, not a dosing protocol, and not a recommendation to obtain or use anything described here. Talk to a licensed clinician about anything concerning your health. Read the full disclaimer.
Reviewed against editorial standards Updated
The short answer
DAC stands for Drug Affinity Complex, a group attached to the peptide that binds albumin in blood and extends how long the molecule circulates from minutes to days. All three published human papers under the CJC-1295 name used the version with the linker [1] [2] [3], and so did the only registration the name carries [4].
So every half-life figure, every duration figure and every statement about the shape of growth hormone release quoted for CJC-1295 was measured on the linker version. This page could find no published study of the no-DAC form on any endpoint, in any species.
Side by side
| Property | CJC-1295 without DAC | CJC-1295 with DAC |
|---|---|---|
| The molecule | Growth hormone releasing hormone 1-29 with four amino acid substitutions, and nothing added | The same peptide, unchanged in sequence, plus a Drug Affinity Complex linker that bonds it to albumin in blood |
| Evidence grade on this site | Not graded here. The source review a grade is derived from has not been run | Not graded here, same reason |
| Published human studies of this form | None found | Three: two randomised placebo-controlled pharmacology studies in healthy adults [1] [2], and a serum protein profiling analysis [3] |
| Estimated half-life reported | Not measured in any published study this page could find | 5.8 to 8.1 days, estimated in the ascending-administration study [1] |
| What those studies measured | Not applicable | Concentrations in blood only: plasma growth hormone, IGF-1, pulse frequency and amplitude, and circulating protein profiles [1] [2] [3]. No body composition, strength, recovery or sleep endpoint appears in any of the three |
| Registered trials | None under this name | One, NCT00267527, a randomised double-blind placebo-controlled phase 2 in HIV associated visceral obesity, listed enrolment 120, start December 2005 [4] |
| Status of that registration | Not applicable | Terminated. The registry gives no reason, records no posted results, and was last updated on 12 October 2006 [4] |
Why the two get mixed up
The two share a name, and the shorter version of it is what most marketing uses. A product listed as CJC-1295 may be either form, and the distinguishing three letters get dropped from headlines, blend names and blog copy.
The chemistry encourages the same reading and is right about one thing. The base peptide really is identical: same sequence, same substitutions, same receptor. What the linker changes is how long that peptide stays in circulation, which sounds like a detail of convenience, and it is the difference that decides which of the two has ever been measured in a person.
A third name pulls the other way. Sermorelin is sold as GRF 1-29 and the no-DAC form as Mod GRF 1-29, so that form is confused upward with its long-acting sibling and sideways with a different molecule that has an approval history.
What the published record covers for each
The published record for the linker version is small and human. Two randomised, placebo-controlled, double-blind ascending studies in healthy adults aged 21 to 61, given subcutaneously, reported mean plasma growth hormone rising 2 to 10 fold for six days or more after a single administration and mean IGF-1 rising 1.5 to 3 fold for nine to eleven days, with an estimated half-life of 5.8 to 8.1 days [Human RCT] [1]. Those are blood concentrations, and no functional or clinical endpoint appears in the paper.
The second study complicates the argument people are actually having, and is usually left out of it. Sampling every 20 minutes across a 12 hour overnight window in healthy men, before and one week after a single administration, the investigators found the frequency and magnitude of growth hormone pulses unaltered, and reported that pulsatile secretion persists during continuous stimulation. What moved was the floor between the pulses: trough growth hormone rose 7.5 fold and mean growth hormone rose 46 percent [Human RCT] [2].
Those two papers are almost always cited one at a time, in opposite directions. The first is used to argue that a long-acting analogue produces a flat, sustained elevation unlike anything a body does on its own, the standard criticism of the linker version. The second is used to argue that the natural pulse pattern survives. Both are reported here, and the reading that fits them together is that the pulses continued while the baseline underneath them was lifted several fold. Citing only the less flattering of the two would be the evidentiary double standard this site exists not to have.
A third paper profiled serum proteins in normal adult subjects after activation of the growth hormone and IGF-1 axis by the same compound, reporting changes in the circulating protein profile [Human RCT] [3]. That is a measurement in blood again, one layer along rather than closer to an outcome.
The programme stopped in 2006. NCT00267527, a phase 2 in HIV associated visceral obesity, was submitted on 20 December 2005 with a listed enrolment of 120. The registry records it as terminated, gives no reason and posts no results, and was last updated on 12 October 2006 [4]. Nothing has been registered under the name since.
For the form sold without the linker there is nothing to set beside any of this. No published study of it could be found, and the duration and pulse-shape figures quoted for it trace to vendor and community writing rather than to a study of that compound [Anecdote] [5].
One further piece belongs to the blend rather than to either product: a 2026 review for orthopaedic and sports medicine physicians recorded that CJC-1295 with ipamorelin has been measured on maximum tetanic tension in murine models of glucocorticoid-induced muscle loss, those findings limited to animal studies [Animal] [7]. Which form sits inside a given blend is a question the label answers and the literature does not.
Our takeOne linker separates two products, and also separates a compound with three published human measurements from one with none. The two papers behind those measurements disagree about the thing buyers argue over, and both are on this page for that reason.
Frequently asked questions
What does DAC actually stand for?
Drug Affinity Complex. It is a chemical group that bonds the peptide to albumin, the most abundant protein in blood, so the molecule is carried in circulation rather than cleared within minutes. The ascending-administration study estimated the resulting half-life at 5.8 to 8.1 days [1].
Does the long-acting form flatten out the natural growth hormone pulses?
The two published studies point in different directions and both were measured. One reports mean plasma growth hormone raised for six days or more after a single administration [1], the basis of the sustained-elevation criticism. The other sampled every 20 minutes overnight and found pulse frequency and magnitude unaltered, with trough growth hormone raised 7.5 fold [2]. Read together, the pulses continued while the baseline underneath was lifted several fold.
Why did the phase 2 trial stop?
The registry does not say. NCT00267527 is recorded as terminated with no reason given, no posted results and a last update of 12 October 2006 [4]. Accounts naming a specific reason circulate in secondary sources, and none of them could be traced to a primary document for this page, so this page states no reason. It also states no participant figure other than the listed enrolment of 120 that appears on the registry record itself.
Did any of the studies measure body composition or strength?
No. The three published human papers measured plasma growth hormone, IGF-1, pulse frequency and amplitude, and circulating protein profiles [1] [2] [3]. None carried a body composition, strength, recovery or sleep endpoint, and the one trial that would have measured a clinical outcome is the terminated phase 2 [4].
Are both prohibited in sport?
Growth hormone releasing hormone analogues sit in class S2 of the WADA 2026 Prohibited List, prohibited at all times rather than in competition only, and both forms fall inside that entry [6].
References
- Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. 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. J Clin Endocrinol Metab. 2006. PMID 16352683 DOI 10.1210/jc.2005-1536
- Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006. PMID 17018654 DOI 10.1210/jc.2006-1702
- Sackmann-Sala L, Ding J, Frohman LA, Kopchick JJ. 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 Horm IGF Res. 2009. PMID 19386527 DOI 10.1016/j.ghir.2009.03.001
- ConjuChem. A multicenter, randomized, placebo-controlled, double-blind, phase 2 study to evaluate the efficacy and safety of CJC 1295 administered for 12 weeks in HIV infected patients with HIV associated visceral obesity (NCT00267527). First submitted 20 December 2005, listed enrolment 120, start December 2005, listed completion September 2006. Registry status terminated, with no reason recorded and no results posted; last update submitted 12 October 2006. Read from the ClinicalTrials.gov v2 API on 2 August 2026. ClinicalTrials.gov. 2006. Source document
- Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev. 2018. PMID 28400207 DOI 10.1016/j.sxmr.2017.02.004
- World Anti-Doping Agency. The 2026 Prohibited List, international standard, effective 1 January 2026. WADA. 2026. Source document
- Mayfield CK, Bolia IK, Feingold CL, Lin EH, Liu JN, Rick Hatch GF, Gamradt SC, Weber AE. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. Am J Sports Med. 2026. PMID 41476424 DOI 10.1177/03635465251357593