Comparison / two pharmacokinetic forms
CJC-1295 DAC vs No-DAC (Modified GRF 1-29) in the Research Literature
Two peptides, one name, very different kinetics. A side-by-side reading of the albumin-conjugated long-acting form and the short-acting no-DAC sequence.
What is CJC-1295 DAC?
CJC-1295 DAC is the albumin-conjugated, long-acting form of the peptide. The two species sold under the CJC-1295 name are pharmacokinetically very different, and confusing them is the most common error in the popular literature [8]. The DAC ("Drug Affinity Complex") variant carries a maleimidopropionyl linker that covalently binds the free thiol on circulating serum albumin, extending the plasma half-life toward that of albumin and giving a multi-day duration [2]. The no-DAC form keeps the same four stabilizing substitutions but lacks that handle, so it is short-acting [8].
The reason this distinction matters so much is that nearly every headline number associated with CJC-1295 belongs to the DAC form specifically. The 5.8-to-8.1-day half-life, the up-to-28-day IGF-1 elevation after repeated dosing, the 4-fold GH output in rats — all describe the albumin conjugate [1][2]. The no-DAC Modified GRF (1-29) shares the sequence but not the kinetics, so a reader who treats the two as one will systematically overestimate how long the short-acting form lasts. Keeping them apart is the single most useful thing to get right about this compound.
What is CJC-1295 DAC?
CJC-1295 DAC is the albumin-conjugated, long-acting form; in rats it produced roughly 4-fold higher GH AUC than unconjugated peptide and remained detectable in plasma beyond 72 hours [2]. In healthy adults, the DAC form's estimated half-life was 5.8 to 8.1 days, and IGF-1 stayed elevated for up to 28 days after multiple doses [1].
What is CJC-1295 with DAC?
The DAC variant carries a maleimide linker that covalently binds circulating serum albumin, extending the plasma half-life toward that of albumin and giving a multi-day duration [2]. "DAC" stands for Drug Affinity Complex — the albumin-binding chemistry is the entire reason the long-acting form lasts days rather than minutes.
The No-DAC Form: Modified GRF (1-29)
The no-DAC form is the short-acting counterpart, and it has its own name in the marketplace: Modified GRF (1-29).
The No-DAC Form: Modified GRF (1-29)
The no-DAC, tetrasubstituted GHRH(1-29) — usually sold as Modified GRF (1-29) — retains CJC-1295's four protease-resistant substitutions but omits the albumin-binding DAC moiety, so its duration of action is much shorter than CJC-1295 DAC [8]. Reference material describes it as a synthetic GHRH analog with the four stabilizing changes and a clearance closer to native GHRH(1-29) [8]. Its half-life sits in the minutes-to-hours range, reflecting native GHRH kinetics with only the protease resistance added [8].
Modified GRF (1-29) and How It Differs from CJC-1295 DAC
Modified GRF (1-29) and CJC-1295 DAC share the same sequence backbone and the same four substitutions, and both target the GHRH receptor — but only the DAC form binds albumin [2][8]. That single chemical difference is the whole story: it converts a minutes-to-hours peptide into a multi-day one. A protocol written for one is not a protocol for the other, which is why the marketplace habit of treating them as interchangeable is a genuine source of confusion [8].
Reading the two forms side by side
Put the two forms in one table and the difference resolves into four rows: sequence backbone, albumin binding, half-life, and duration of action. The backbone and the four protease-resistant substitutions are shared. Albumin binding is present only in the DAC form. Half-life is 5.8 to 8.1 days for DAC versus minutes-to-hours for no-DAC. Duration follows half-life directly — multi-day for DAC, brief for no-DAC [1][2][8].
That single binding difference cascades through everything a reader cares about. It changes how often each was studied, how long a single dose keeps IGF-1 elevated, and how the published findings should be mapped onto each form. The strongest human data — the 5.8-to-8.1-day half-life and the up-to-28-day IGF-1 elevation — belong specifically to the DAC conjugate [1]; they do not describe the short-acting no-DAC peptide. Reading a DAC finding as if it applied to Modified GRF (1-29) is precisely the conflation the literature warns against [8].
How much CJC-1295 DAC should I take?
Human PK work used single subcutaneous doses of 30 to 90 micrograms per kilogram of the DAC form [1][3]. Because the DAC form has a 5.8-to-8.1-day half-life, it was studied on infrequent schedules rather than daily ones [1]. No approved human dose exists, and fixed-dose figures circulating online are not derived from controlled trials [7].
For the short-acting no-DAC form, see how the literature handled it in the research dosing context. The same caveat applies: published human exposure is limited to early studies, and community "protocols" are not validated regimens [7]. Whichever form is meant, CJC-1295 is not approved for human use, and nothing here is a dosing recommendation.
The practical takeaway is simple. If a source quotes a half-life, a duration, or a dosing interval for 'CJC-1295' without saying which form it means, the number is ambiguous and probably wrong for at least one of the two species [8]. Naming the form — DAC or no-DAC — is the first thing any accurate statement about this compound has to do.