Two vials can carry almost the same name, CJC-1295 and CJC-1295 with DAC, and behave completely differently. One is gone from the body in well under an hour. The other can last about a week. The difference comes down to one small chemical attachment. This guide explains what that attachment does, what the human studies actually measured, and why the naming causes so much confusion.
The common assumption, and why it is wrong
Most people read "with DAC" and "no DAC" as two strengths of the same compound, like regular and extra strength. They are not. They are two different research tools built from the same starting molecule, and they answer different scientific questions.
There is a second surprise. In the scientific literature, the name CJC-1295 belongs to the DAC version. The compound sold as "CJC-1295 no DAC" has a more accurate name, Mod GRF 1-29, and it is a different molecule.
The short answer
- CJC-1295 no DAC (Mod GRF 1-29) is a modified copy of the brain's growth-hormone-releasing signal. Four swapped building blocks make it tougher than the natural signal, but it still clears the body quickly, in well under an hour by common estimates.
- CJC-1295 with DAC is the same modified signal plus a chemical hook that grabs onto albumin, the most common protein in blood. Attached to albumin, it avoids breakdown and removal. In human studies its half-life was about 6 to 8 days.
Same message to the pituitary gland. Very different timing.
Start with the natural signal
Growth hormone is made in the pituitary gland, at the base of the brain. The main signal that tells it to release growth hormone is GHRH (growth-hormone-releasing hormone), a 44-amino-acid peptide sent from the hypothalamus.
Two facts about GHRH explain everything that follows.
- Only the first 29 amino acids are needed. Researchers found in the early 1980s that this front section carries the full activity. That 29-amino-acid piece is called GRF 1-29, and it is the basis of sermorelin.
- It lasts only minutes. An enzyme in the blood called DPP-4 clips GHRH near its front end and switches it off almost immediately. Other enzymes finish the job.
So the research problem was simple to state: how to keep this signal intact long enough to study it.
Fix one: four swapped building blocks (the no-DAC version)
The first fix changes the peptide itself. Chemists replaced four of the 29 amino acids, at positions 2, 8, 15 and 27, with alternatives that enzymes struggle to cut. The swap at position 2 is the important one. It uses a mirror-image form of alanine (D-alanine), which DPP-4 cannot recognize.
The result is Mod GRF 1-29, short for modified GRF 1-29, sometimes written as tetrasubstituted GRF 1-29. It still binds the same GHRH receptor and sends the same message. It simply survives longer, often estimated at about 30 minutes, compared with a few minutes for the natural signal. That estimate is widely repeated but has not been well characterized in published human studies.
Fix two: a hook that grabs albumin (the DAC version)
The second fix goes further. DAC stands for Drug Affinity Complex, a technology developed by the Canadian company ConjuChem in the early 2000s.
Think of albumin as a bus that circulates in the blood for weeks. DAC gives the peptide a way to board that bus and stay on it.
- Chemists added one extra amino acid, a lysine, to the end of Mod GRF 1-29.
- On that lysine they attached a small reactive group called maleimidopropionic acid (MPA).
- After the peptide enters the blood, MPA forms a permanent chemical bond with one specific spot on albumin (a site called cysteine-34).
Riding on albumin, the peptide is too large to be filtered out by the kidneys and is shielded from the enzymes that would break it down. In a 2005 rat study, the albumin-bound peptide was still detectable in the blood more than 72 hours after a single administration. That study, by Jetté and colleagues in Endocrinology, is where the name CJC-1295 first appeared.
Side by side
| CJC-1295 no DAC (Mod GRF 1-29) | CJC-1295 with DAC | |
|---|---|---|
| Built from | GRF 1-29 with four swapped amino acids | The same, plus a lysine carrying an MPA hook |
| Receptor | GHRH receptor | GHRH receptor |
| Binds albumin? | No | Yes, permanently |
| Half-life | Short, commonly estimated at about 30 minutes | About 5.8 to 8.1 days in human studies |
| Published human data | Very little | Two small studies in healthy adults (2006), plus one halted trial |
| Accurate name | Mod GRF 1-29 | CJC-1295 |
| Evidence tier | D | D |
What the human studies measured
Almost all the human data on CJC-1295 comes from two small studies in healthy adults, both published in the Journal of Clinical Endocrinology & Metabolism in 2006. Both studied the DAC version.
Study one: how long it lasts (Teichman and colleagues). Two randomized, placebo-controlled trials in healthy adults tracked the compound over four and seven weeks.
- After a single administration, average growth hormone levels rose 2- to 10-fold for 6 days or more.
- IGF-1, the hormone the liver releases in response to growth hormone, rose 1.5- to 3-fold for 9 to 11 days.
- The measured half-life was 5.8 to 8.1 days.
Study two: what happens to the pulses (Ionescu and Frohman). This is the more interesting one, and it challenges a popular claim.
Growth hormone is normally released in pulses, bursts separated by quiet periods. A common argument online is that a long-acting signal must flatten those pulses into a constant "bleed." The researchers tested exactly that question in healthy men aged 20 to 40, and that is not what they found.
- The pulses kept their normal size and frequency.
- The baseline between pulses rose 7.5-fold.
- Average growth hormone rose 46%, and IGF-1 rose 45%.
In other words, the DAC version did not replace the natural rhythm. It lifted the floor underneath it. The authors concluded that the higher baseline, not the pulses, drove the rise in IGF-1. One small study does not settle the question, but it is the only direct human measurement, and it points the other way from the popular story.
For the no-DAC version, the record is thin. Mod GRF 1-29 has almost no published human data of its own. Much of what is said about it online is inferred from sermorelin, which it closely resembles, or from the DAC studies, which it does not.
Where the research stopped
CJC-1295 with DAC moved into a mid-stage clinical trial in 2006, testing whether it could reduce excess abdominal fat in people with HIV-associated lipodystrophy. The trial had enrolled 192 participants across North and South America.
In July 2006, ConjuChem halted the trial after a participant died. Whether the death was related to the compound was never publicly established. Development did not resume, and CJC-1295 was never approved for any use.
The regulatory record since then is short and clear.
- December 2024: the FDA's Pharmacy Compounding Advisory Committee reviewed five forms of CJC-1295, with and without DAC. The committee voted against adding each one to the list of substances pharmacies may compound, by margins of 12 to 1 or 13 to 0.
- Sport: all GHRH analogs, including CJC-1295, are prohibited at all times under the World Anti-Doping Agency's list.
Why the naming is so confusing
The confusion is mostly historical. CJC-1295 was the code name ConjuChem gave its albumin-binding compound. When the unhooked version began circulating as a research material, it borrowed the more famous name and added "no DAC." That makes it sound like CJC-1295 minus a feature, when it is really Mod GRF 1-29, a different molecule with a different profile and far less published research behind it.
The practical lesson for anyone reading a label or a certificate of analysis: check the molecular weight, not just the name. The DAC version is noticeably heavier because of the extra lysine and the MPA hook. A certificate of analysis should report a mass that matches the compound actually named on the vial.
The big takeaway
CJC-1295 with DAC and CJC-1295 no DAC send the same message to the same receptor. What separates them is time. One small chemical hook turns a signal that lasts minutes into one that lasts about a week, by letting the peptide ride on albumin. The one human study that looked closely found that this long signal raised the baseline while leaving the body's natural pulses in place. Beyond that, the evidence for both is early. Neither was ever approved, and the only clinical program behind them ended in 2006.
For how these compare with sermorelin, tesamorelin and ipamorelin, see Sermorelin vs Tesamorelin vs Ipamorelin.
Frequently asked questions
What is the difference between CJC-1295 with DAC and without DAC?
Both are modified versions of GHRH, the brain's signal for growth hormone release, and both act on the same receptor. The DAC version carries a chemical hook that binds permanently to albumin in the blood, which extends its half-life to about 6 to 8 days in human studies. The version without DAC has no hook and is commonly estimated to clear in about 30 minutes.
What does DAC stand for?
DAC stands for Drug Affinity Complex. It is a reactive chemical group, maleimidopropionic acid, attached to the peptide so that it bonds to albumin, the most common protein in blood.
Is CJC-1295 no DAC the same as Mod GRF 1-29?
Yes. "CJC-1295 no DAC" is the common market name for Mod GRF 1-29, a 29-amino-acid GHRH fragment with four amino acid substitutions. In the scientific literature, the name CJC-1295 refers to the DAC version.
What is the half-life of CJC-1295 with DAC?
In a 2006 study in healthy adults, the measured half-life was 5.8 to 8.1 days. The no-DAC version is commonly estimated at about 30 minutes, though that figure has not been well characterized in published human studies.
Does CJC-1295 with DAC stop natural growth hormone pulses?
In the one human study that measured this directly, no. Researchers found that pulse size and frequency stayed normal while the baseline level between pulses rose 7.5-fold. It was a small study, so the question is not fully settled.
Is CJC-1295 FDA approved?
No. Its only clinical program was halted in 2006 and never resumed. In December 2024, an FDA advisory committee voted against adding any form of CJC-1295 to the list of substances pharmacies may compound.