CJC-1295 With DAC vs Without DAC: What’s the Difference?

DAC stands for Drug Affinity Complex. It is a chemical modification that lets the peptide bind covalently to circulating albumin, the most abundant plasma protein. Because albumin turns over slowly, a molecule attached to it is cleared far more slowly than the unbound peptide.

Think of an unmodified peptide as a message dropped into a fast-moving river: it is swept away and broken down within minutes to hours. DAC is like tying that message to a large, slow-moving log — the albumin protein — that the body does not clear out for days. The message is the same underlying growth-hormone-releasing-hormone sequence; what changes is only how long it stays in circulation to keep acting. Beyond that one analogy, the rest of this article uses the precise pharmacological terms rather than further comparisons.

The measured consequence in humans is large. In the published ascending-dose trials, CJC-1295 with DAC had a terminal half-life of 5.8 to 8.1 days. [1] Half-life is the time it takes for the concentration of a substance in the blood to drop by 50%; a longer half-life means a single dose keeps producing an effect for longer, and it also means the substance takes longer to fully clear once dosing stops. A growth-hormone-releasing-hormone analog without that modification is cleared on a scale of minutes to hours, which is a different pharmacological object even though the core sequence is related.

Half-life is not a quality ranking. A longer half-life changes the questions that have to be asked about feedback, timing and accumulation; it does not make a molecule better.

HUMAN CLINICAL TRIAL

The pulsatility finding is the subtle one. Growth hormone is normally released in bursts, and a concern with any long-acting stimulus is that it flattens that rhythm into a continuous signal. It did not. Pulses continued at the same frequency and size, while the baseline between pulses rose sharply, and the authors concluded that the higher trough, rather than bigger pulses, explained the IGF-I rise. [2]

Why does that distinction matter to a reader rather than just to a researcher? Continuous, non-pulsatile growth-hormone exposure is generally considered less like the body’s own signalling pattern than pulsed exposure, so a study confirming that pulses are unchanged is evidence that DAC-modified CJC-1295 is topping up the existing rhythm rather than replacing it with a flat signal. That is a specific, narrow finding about signal shape, not a statement about any downstream outcome such as body composition.

Both 60 and 90 micrograms per kilogram produced similar results, which suggests the response had already plateaued across that range in this small study. [2] A plateau means raising the dose further did not produce a proportionally larger hormonal response in this data set — it does not establish where above or below this range the relationship might behave differently.

None that is published and indexed. A search of the primary literature returns no human clinical trial of CJC-1295 without DAC, sometimes marketed as modified GRF 1-29.

This matters because the figures quoted for no-DAC products in circulation are routinely lifted from the two DAC trials. A half-life of 5.8 to 8.1 days, a six-day growth-hormone elevation, and an IGF-I response lasting nine to eleven days are all properties measured for a molecule engineered to bind albumin. [1] Removing that modification removes the reason those numbers exist.

This is not a minor labelling issue. Pharmacokinetics — how fast a substance appears, spreads and clears — is specific to the exact molecule, dose, route and species tested. A no-DAC peptide, lacking the albumin-binding tail, would be expected on structural grounds to clear on a timescale of minutes to a few hours rather than days, but “would be expected” is a structural inference, not a measured human result. No published study has measured its actual half-life, its actual GH or IGF-I response, or its actual safety profile in people.

Cross-form transfer is the same error as cross-trial comparison. A number belongs to the molecule and protocol that produced it.

Check three things in order. Which form was studied, with DAC or without. Which population and protocol produced the number. And whether the source is reporting a measured value or repeating a figure that originated somewhere else.

Applied to the current literature, the honest summary is short: CJC-1295 with DAC has a defined human pharmacodynamic profile from two 2006 studies in healthy volunteers, and CJC-1295 without DAC does not have one. [1][2]

Neither form is an approved drug. The FDA proposed in December 2024 that CJC-1295 in all listed salt and DAC variants be excluded from the section 503A bulk drug substances list. [3]

For the full component-by-component audit, continue to the CJC-1295 and ipamorelin evidence review.