CJC-1295 With DAC vs. No DAC: What's the Difference?

Two vials. One says CJC-1295 with DAC. The other says CJC-1295 no DAC. Most people figure it's one compound in two strengths, like regular and extra strength. It isn't.

"CJC-1295 no DAC" is a different molecule with a borrowed name

In the scientific papers, the name CJC-1295 belongs to the DAC version. That's it. The no-DAC compound has its own name, Mod GRF 1-29, and its own chemistry. It just picked up the more famous name on the way to market.

The proof: CJC-1295 with DAC vs no DAC, traced back to 2005

Here's what's actually going on.

Both start from a signal that barely lasts. The brain tells the pituitary gland to release growth hormone with a peptide called GHRH. Only its first 29 building blocks are needed to do the job. But an enzyme in the blood clips it near the front end. In healthy men, that 29-block piece had a half-life (the time it takes for half of it to clear from the blood) of about 4 minutes (Soule et al., JCEM 1994). Picture a note that gets shredded soon after it's sent.

Fix one made the note tougher. Chemists swapped four of those 29 building blocks, at positions 2, 8, 15 and 27. The big one is position 2. It's now a mirror-image version of alanine that the clipping enzyme can't recognize (Frohman et al., J Clin Invest 1989). That's Mod GRF 1-29, the "no DAC" one. How long does it last in people? No published study has measured it. The "about 30 minutes" you'll see online has no study behind it that we could find.

Fix two gave it a ride. In Montreal, a company called ConjuChem added one more building block, a lysine, carrying a tiny chemical hook that latches onto albumin, the most common protein in blood. Albumin is like a bus that circulates for weeks, and now the peptide had a seat. In rats it was still in the blood more than 72 hours later. That 2005 paper is the first on PubMed to use the name CJC-1295 (Jetté et al., Endocrinology 2005).

Then they measured it in people. In a 2006 study in healthy adults, CJC-1295's estimated half-life came out at 5.8 to 8.1 days (Teichman et al., JCEM 2006). One hook took a signal that's gone in minutes to one that hangs around for about a week.

So why should you care? The hook shows up on the scale. The DAC version weighs about 3,647 daltons. Mod GRF 1-29 weighs about 3,368 (daltons are just the unit chemists weigh molecules in). The LC-MS identity test on a certificate of analysis (COA) weighs the molecule, so that gap of roughly 280 tells you which one is in the vial. If the mass on the COA doesn't match the name on the label, something's off.

"Can I trust what I read about the no-DAC version?" Carefully. It has almost no published human data of its own. A lot of what's online is borrowed from the DAC studies, which tested a different molecule. And the DAC version's own story is short. Its one registered mid-stage trial was terminated in 2006 (ClinicalTrials.gov), and it was never approved.

The big learning lesson

Keep reading: Sermorelin vs tesamorelin vs ipamorelin · Peptide half-life explained · How to read a peptide certificate of analysis

Frequently asked questions

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. In the scientific papers, the name CJC-1295 refers to the DAC version.

What does DAC mean in CJC-1295?

Drug Affinity Complex. It's a small chemical hook, carried on an added lysine, that lets the peptide bond to albumin, the most common protein in blood.

What is the half-life of CJC-1295 with DAC?

In a 2006 study in healthy adults, it was estimated at 5.8 to 8.1 days. No published study has measured the no-DAC version's half-life in people.