CJC-1295 vs CJC-1295 DAC: Same Peptide, Different Clock
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Few naming situations in peptide research cause more confusion than CJC-1295. Two distinct research compounds circulate under nearly the same name: the base GHRH analogue, correctly called Mod GRF 1-29, and the version carrying a drug affinity complex, the DAC. The peptide backbone is the same; the clock attached to it is not. This page explains what the DAC actually changes, from a laboratory research perspective. Nothing here is medical advice, and both compounds are research materials without marketing authorisation anywhere.
What are the two forms?
Both start from GHRH(1-29), the shortest fully active fragment of human growth hormone releasing hormone, stabilised with four amino-acid substitutions at the positions most vulnerable to enzymatic cleavage. That stabilised backbone alone is Mod GRF 1-29, often labelled CJC-1295 without DAC.
CJC-1295 with DAC adds a maleimidopropionic acid group on a lysine linker. That reactive group bonds covalently to circulating albumin after administration in the published models, and the peptide then travels with the albumin molecule, inheriting its multi-day circulation time.
How do their mechanisms differ?
At the receptor there is no difference worth the name: both forms are GHRH receptor agonists with the same recognition pharmacology. Everything that separates them is pharmacokinetic. The base peptide acts in minutes and is cleared in minutes, producing a sharp, short stimulus that mimics the shape of an endogenous secretion pulse. The DAC form maintains receptor exposure continuously for days. In the published human data, Teichman and colleagues reported half-lives of roughly six to eight days for the DAC form, with IGF-1 elevations lasting up to two weeks after single administrations.
The scientifically interesting finding sits in the second study: Ionescu and Frohman reported that pulsatile secretion persisted even under continuous stimulation by the DAC form, with overall secretion amplified rather than flattened. For axis physiology research that made the DAC form a tool for a question the base peptide cannot ask: what happens to a pulsatile system under constant drive.
| Mod GRF 1-29 (no DAC) | CJC-1295 with DAC | |
|---|---|---|
| Backbone | GHRH(1-29), 4 substitutions | Identical |
| Extra chemistry | None | Albumin-binding drug affinity complex |
| Kinetic profile | Minutes, pulse-shaped | Days, continuous |
| Research question it fits | Pulse dynamics, acute receptor studies | Sustained exposure, chronic models |
| Marketing authorisation | None | None |
Which form suits which research application?
The choice between the two forms is a choice of experimental time base. Work on pulse dynamics, acute receptor signalling or rapid washout designs calls for the base peptide, whose stimulus can be timed and removed. Chronic exposure models, receptor desensitisation questions and long-duration study designs call for the DAC form, which holds exposure steady without repeated dosing of the model system. Publications that fail to say which form they used are a known reading hazard in this literature; the kinetics differ so much that results from one form do not transfer to the other.
What is the regulatory status?
Neither form is an authorised medicine anywhere. Both fall under the WADA Prohibited List section S2 entry for GHRH analogues, where CJC-1295 is one of the named examples; the prohibition covers athletes at all times and the live list is the binding reference. Research material supplied under a research use only framework is not a medicine and not for human or veterinary use.
Research sourcing and quality checks
Because the two compounds differ by a single chemical group, documentation is the only way a buyer can know which one is in the vial. The product label, the batch number and the certificate of analysis should agree on the exact identity, DAC or no DAC, and the molecular mass on the certificate is the decisive line: the DAC group adds measurable mass. Both forms are in our catalog as research reagents, Mod GRF 1-29 and CJC-1295 DAC, and where a batch has been tested its report is published in the lab reports archive. Our guide on reading a certificate of analysis explains how to check identity against mass spectrometry data.
Conclusion
Same backbone, same receptor, different clock: the DAC is a pharmacokinetic device, not a new pharmacology. The base peptide asks pulse-shaped questions, the DAC form asks continuous-exposure questions, and the published literature answers each with the matching tool. For procurement the practical rule is blunt: if the paperwork does not state which form it is, assume nothing.
References
- Teichman SL et al. Prolonged stimulation of growth hormone and IGF-1 secretion by CJC-1295 in healthy adults. J Clin Endocrinol Metab 2006. PubMed
- Ionescu M, Frohman LA. Pulsatile secretion of growth hormone persists during continuous stimulation by CJC-1295. J Clin Endocrinol Metab 2006. PubMed
- WADA Prohibited List, section S2, current edition. wada-ama.org