CJC-1295 DAC vs No-DAC: Research Comparison

"CJC-1295 with or without DAC?" is one of the most common questions about this GHRH analog, and the answer is entirely about kinetics. Both forms share the same core peptide and the same target — the GHRH receptor on pituitary somatotrophs. The difference is a single added element, the Drug Affinity Complex (DAC), and it transforms the compound's half-life from minutes into days. This is a research-use-only comparison of CJC-1295 DAC and CJC-1295 no-DAC.

What is the DAC?

DAC stands for Drug Affinity Complex — a small maleimido-propionic-acid group attached to the peptide that binds covalently to circulating albumin. Albumin is an abundant, long-lived carrier protein, so tethering the peptide to it shields the molecule from rapid enzymatic clearance and from filtration by the kidney. The practical result studied in the literature is a dramatically extended half-life: the albumin-bound peptide acts as a slow-release depot.

Critically, the DAC does not change what the peptide does at its receptor — it changes how long the peptide survives in circulation to keep doing it. Intrinsic activity at the GHRH receptor is the same for both forms. That separation of pharmacodynamics (what it does) from pharmacokinetics (how long it lasts) is exactly why the DAC-versus-no-DAC choice is framed as a kinetics question.

No-DAC: modified GRF 1-29

The no-DAC form is frequently called modified GRF 1-29 (or CJC-1295 without DAC). It is a short, stabilized GHRH(1-29) fragment — the minimal active fragment of GHRH, with four amino-acid substitutions that resist enzymatic breakdown. Its half-life is measured in minutes to roughly half an hour in the models reported. Those kinetics produce a brief, pulse-like GHRH signal that rises and clears quickly — which is why it is the form most often paired with a ghrelin-receptor agonist in the CJC-1295 + ipamorelin stack, where a discrete pulse is the goal.

DAC: the long-acting form

Add the DAC and the reported half-life jumps from minutes to roughly six to eight days, because the albumin-bound depot releases the peptide slowly over that window. In research terms this means a sustained, tonic elevation of the GHRH signal rather than a discrete pulse. A single administration of CJC-1295 DAC maintains an elevated GHRH input across days in model systems, which is the property that makes it useful for studying chronic, steady-state stimulation. The trade-off characterized in the literature is duration versus pulsatility — the DAC form gains the former at the cost of the latter.

Side-by-side

• Core peptide: identical GHRH-analog backbone in both
• DAC group: present in CJC-1295 DAC, absent in no-DAC
• Albumin binding: DAC tethers to albumin; no-DAC circulates free and clears fast
• Half-life: minutes-to-~30 min (no-DAC) vs ~6–8 days (DAC) in reported models
• Signal shape: discrete pulse (no-DAC) vs sustained/tonic elevation (DAC)
• Intrinsic activity: identical at the GHRH receptor — only the kinetics differ
• Common research pairing: no-DAC with ipamorelin for pulse-like input; DAC alone for steady GHRH tone

Why pulsatility matters in GH research

Endogenous growth hormone is released in pulses, not as a steady stream, and a great deal of GH biology depends on that pulsatile pattern. This is the deeper reason the DAC distinction matters for study design: a short-acting GHRH input (no-DAC) can be timed to reconstruct a natural-looking pulse, whereas a long-acting input (DAC) produces a flatter, more continuous elevation. Researchers choose the form whose kinetic signature matches the physiology they want to model — there is no single 'correct' answer outside the context of the experiment.

Which form for which research question?

If the variable of interest is the timing and shape of a GH pulse, the short-acting no-DAC CJC-1295 is the cleaner tool. If the question is the effect of a sustained GHRH signal held steady over days without re-dosing, the DAC form holds that input constant. Neither is "stronger" — they answer different questions, and both bind the same receptor with the same potency.

Reconstitution is the same for both

Both forms are supplied lyophilized and dissolved in bacteriostatic water before in-vitro use. Use the reconstitution calculator to convert vial size and diluent volume into concentration and aliquot volume. Every lot ships lyophilized in multi-vial research kits from our US facility within 48 hours with tracking.