Key takeaways
- “CJC-1295” refers to two different compounds: one with a Drug Affinity Complex (DAC) and one without.
- Both are synthetic analogs of GHRH(1–29) with four stabilizing amino-acid substitutions.
- The DAC version binds albumin and persists for days; the no-DAC version (Mod GRF 1–29) acts for roughly half an hour.
- Molecular weights differ, so the COA’s mass-spec result tells you which one you have.
“CJC-1295” is one of the most confusing names in peptide research, because it is used for two different molecules. One persists for about a week in published pharmacokinetic studies; the other is cleared in roughly half an hour. Knowing which one you are working with changes how a study has to be designed.
Background: GHRH and GRF 1–29
Growth-hormone-releasing hormone (GHRH) is produced in the hypothalamus and signals pituitary somatotrophs to release growth hormone (GH) in pulses. GH in turn drives hepatic production of IGF-1. Only the first 29 amino acids of GHRH are needed for full activity at its receptor, a fragment known as GRF 1–29. That fragment, unmodified, is essentially sermorelin, and it is the starting point for both CJC-1295 variants.
The four substitutions
Native GHRH is broken down within minutes, mainly by the enzyme dipeptidyl peptidase-4 (DPP-4). Both CJC-1295 variants carry four amino-acid substitutions, at positions 2, 8, 15 and 27, that make the sequence much more resistant to that enzymatic cleavage. The result is called Modified GRF (1–29).
What “DAC” adds
DAC stands for Drug Affinity Complex: a reactive chemical group attached to the peptide that lets it bind covalently to circulating albumin. Because albumin persists for weeks, the bound peptide is protected from rapid clearance, which is what extends the DAC version’s activity from minutes to days.
Side-by-side comparison
| CJC-1295 with DAC | CJC-1295 No DAC (Mod GRF 1–29) | |
|---|---|---|
| Structure | Modified GRF 1–29 plus DAC linker | Modified GRF 1–29 only |
| Albumin binding | Yes, covalent | No |
| Reported half-life | Roughly 6–8 days in published pharmacokinetic studies | Roughly 30 minutes |
| GH signaling pattern | Sustained elevation over days | Short pulse, closer to physiological release |
| Development history | Early-phase clinical studies; development discontinued | Never developed as an approved drug |
| Regulatory status | Not approved | Not approved |
Why the difference matters in research
- Study designA compound active for a week and one active for half an hour need completely different sampling times and endpoints.
- PhysiologyPulsatile GH release and sustained GH elevation are different signaling states, and they are studied for different questions.
- IdentityProducts labeled simply “CJC-1295” may be either form. Check the full product name and the mass-spec result on the batch COA, since the two have different molecular weights.
Pairing with a ghrelin-receptor agonist
GHRH analogs and ghrelin-receptor agonists such as Ipamorelin act on different receptors. In physiology research, engaging both pathways produces a larger GH response than either alone, which is why the Mod GRF 1–29 / Ipamorelin pairing is so widely studied.
After Hours Labs supplies the no-DAC form, Mod GRF 1–29, on its own and pre-blended with Ipamorelin.
Frequently asked questions
Is Mod GRF 1-29 the same as CJC-1295 without DAC?
Yes. The names refer to the same molecule: GRF 1–29 with four stabilizing substitutions and no albumin-binding group.
How does it relate to sermorelin?
Sermorelin is GRF 1–29 without the substitutions. CJC-1295 adds the four stabilizing substitutions, and the DAC version also adds the albumin-binding group.
Is either form approved as a drug?
No. Neither form is an approved drug, and both are supplied for laboratory research only.
All After Hours Labs products are sold strictly for qualified in-vitro laboratory research. They are not for human or veterinary use, and nothing in this article is medical advice or a recommendation for use in people or animals.
