Quick answer: in CJC-1295 no DAC vs with DAC, the only structural difference is the “DAC” (Drug Affinity Complex), a chemical group that lets the peptide bind to albumin in the blood.[1] The DAC version had a half-life of 5.8 to 8.1 days in healthy adults.[2] The no-DAC version, also sold as “mod GRF 1-29”, has never been studied in people, so its half-life, dose and safety are unknown.[4][5]
This guide covers what DAC does, what is measured versus assumed, how each form was discovered, safety and legal status. For the full profile, see CJC-1295 with DAC, and for the popular pairing, our CJC-1295 and ipamorelin guide. The growth hormone peptides hub covers the rest of the family.
What CJC-1295 is, and what DAC adds
Growth hormone-releasing hormone (GHRH) has 44 amino acids, but the first 29 carry its activity. CJC-1295 starts with that 29-amino-acid fragment and swaps four amino acids, at positions 2, 8, 15 and 27, to make it more stable.[4]
The DAC is a lysine carrying a reactive maleimide group. Its developer, ConjuChem in Montreal, reported that it latches onto albumin, the most common protein in blood. In rats, the DAC version was still in plasma beyond 72 hours and released four times more growth hormone over two hours than unmodified GHRH (1-29).[1] Remove the DAC and you have the same four-swap peptide on its own, which sellers call CJC-1295 without DAC or modified GRF (1-29).[5]
Side by side
| CJC-1295 with DAC | CJC-1295 without DAC (mod GRF 1-29) | |
|---|---|---|
| Structure | 29-amino-acid GHRH analog plus albumin-binding DAC | Same analog, no DAC |
| Half-life in humans | 5.8 to 8.1 days | Never measured |
| Published human studies | Three, in 63 healthy adults | None |
| Effect on hormones in people | Growth hormone up for 6+ days, IGF-1 for 9 to 11 days | Not measured |
| Dosing in studies | Single or repeat injections a week or two apart | No studies |
| How it entered the market | Developed as a drug, 2005 to 2006 | First identified in a seized product, 2009 |
| FDA-approved | No | No |
Sources: the human studies,[2] FDA’s review[4] and a 2026 endocrine review.[5]
Half-life: what is measured and what is assumed
For the DAC version, the numbers come from human studies. One injection raised average growth hormone 2- to 10-fold for 6 days or more and IGF-1 1.5- to 3-fold for 9 to 11 days, and repeat doses kept IGF-1 above baseline for up to 28 days.[2] In FDA’s reading of the repeat-dose study, mean half-lives ranged from 5.4 to 9.2 days, with drug still measurable 10 to 13 days after a dose.[4]
For the no-DAC version, nothing has been measured. It is widely described as short-acting, but the 2026 review notes that no human study has reported its half-life.[5] FDA went further on two points:[4]
- The DAC’s role is not proven. A direct comparison of half-lives with and without DAC has never been done, so the four amino-acid swaps may also explain some of the stability.
- Results do not transfer. Because the DAC permanently changes the molecule, FDA said the DAC version’s pharmacology “cannot be extrapolated” to the no-DAC form. FDA found no studies showing the no-DAC form is even pharmacologically active.
“Pulse” vs steady release
The main selling point for the no-DAC form is that a short-acting peptide gives a more natural, pulse-like rise in growth hormone. The 2026 review says this claim comes from extrapolation, mainly from studies of sermorelin, not from studies of the no-DAC peptide itself.[5]
The DAC form did not flatten natural rhythm in the one study that checked. In 12 healthy men, overnight growth hormone pulses kept their number and size a week after a single injection. The rise came mostly from levels between pulses, which went up 7.5-fold, and IGF-1 rose 45%.[3]
In mice unable to make their own GHRH, the DAC form given daily restored normal growth and body composition, while the same dose every 2 or 3 days was less effective.[7]
Is mod GRF 1-29 the same as sermorelin?
No. Sermorelin is the natural GHRH (1-29) sequence; mod GRF 1-29 is that sequence with the four stabilizing swaps.[5] Sermorelin was once FDA-approved and has decades of human studies, mostly in children. See CJC-1295 vs sermorelin and our sermorelin profile.
How each form appeared
- With DAC: described by ConjuChem in 2005 and tested in healthy adults in 2006.[1][2] A phase 2 trial in HIV-related belly fat was terminated in 2006 after a participant died of a heart attack following his 11th weekly dose; his physician suspected undiagnosed coronary disease, and the results were never published.[4][10]
- Without DAC: first described in 2010, when Norway’s doping control laboratory analyzed an unknown preparation seized by police and customs in 2009 and found a 29-amino-acid peptide consistent with CJC-1295 but without DAC.[6][4]
FDA counted at least nine names used for five CJC-1295-related substances and warned that the confusion means a patient could be given a different substance than the one prescribed.[4]
Safety differences
- With DAC: in healthy adults, injection-site reactions in about 70%, headache in 63%, diarrhea in 43%, and flushing with a short blood pressure drop in 30%, with heart rate rising at higher doses. Animal studies found injection-site tissue damage and, in mice, pituitary DNA damage.[4] FDA also noted the DAC group could bind proteins other than albumin.[4]
- Without DAC: no human safety data. FDA found no toxicity, genotoxicity or pharmacology studies, so its risks are simply unknown.[4]
FDA’s compounding safety page, which lists CJC-1295 among substances whose nominations were withdrawn, still names increased heart rate and widespread blood vessel dilation as serious adverse events, along with possible immune reactions.[9] More detail is in CJC-1295 and ipamorelin side effects.
Legal status
On December 4, 2024, FDA’s Pharmacy Compounding Advisory Committee voted on each form separately:[8]
- CJC-1295 without DAC (free base): 0 to 13 against
- CJC-1295 without DAC (acetate): 1 to 12 against
- CJC-1295 with DAC, in its free base, acetate and trifluoroacetate forms: 0 to 13 against each
Neither form is FDA-approved for any use.[4] For dosing questions, see our CJC-1295 and ipamorelin dosage guide; the only human doses on record are for the DAC version.
Questions to ask a clinician
- Which form is in this product, and how was that confirmed?
- If it is the no-DAC form, what human data support its dose and safety?
- How will you monitor IGF-1, heart rate and blood pressure?
- Is there an FDA-approved option for my goal, such as tesamorelin for its approved use?
