CJC-1295 DAC vs No-DAC

The distinction, logged

CJC-1295 DAC vs No-DAC is the distinction that determines almost everything else about how the compound behaves. Both forms share the same hGRF(1-29) backbone with the same four protease-resistant substitutions. What differs is one piece of chemistry: the DAC ("Drug Affinity Complex") form carries a maleimidopropionyl linker that covalently binds the free thiol on Cys34 of circulating serum albumin, forming a peptide-albumin conjugate; the no-DAC form does not ^[2].

That one difference splits the half-life by orders of magnitude. The DAC form's estimated half-life in healthy adults was 5.8 to 8.1 days, with IGF-1 elevation lasting up to 28 days after multiple doses ^[1]. The no-DAC form is short-acting, clearing on a minutes-to-hours timescale. Treating them as interchangeable — which forums and product copy routinely do — is the central error in the popular CJC-1295 literature.

How the DAC form was identified

The DAC design was the product of a screen. A series of hGRF(1-29) analogs bearing a C-terminal maleimidopropionyl-lysine handle were tested; the lead — CJC-1295 — combined four DPP-IV-protective substitutions with covalent albumin bioconjugation and produced a 4-fold increase in GH AUC over two hours versus unconjugated hGRF(1-29) in rats, with peptide detectable beyond 72 hours and enhanced in vitro stability against dipeptidylpeptidase-IV ^[2]. The albumin-conjugate strategy is what converts a short-lived GHRH fragment into a multi-day agent. The effective circulating species after conjugation is not the small peptide but the much larger (~66 kDa) peptide-albumin complex.

Modified GRF (1-29): the no-DAC form

Modified GRF (1-29) is the common name for the no-DAC form. It keeps the four substitutions — D-Ala2, Gln8, Ala15, Leu27 — that block dipeptidylpeptidase-IV cleavage, deamidation, and oxidation, which is why it is "modified" rather than native GHRH(1-29). But it lacks the albumin-binding moiety, so it is short-acting: its clearance reflects native GHRH(1-29) kinetics, on a minutes-to-hours scale rather than days. The label is a frequent source of confusion because product listings often use "CJC-1295" loosely for the no-DAC sequence as well, even though the pharmacokinetics are entirely different ^[2]. When the literature reports a multi-day half-life, it is describing the DAC form; when it describes short-acting behavior, it is the no-DAC Modified GRF (1-29).

Why the split changes how you read the studies

The DAC-versus-no-DAC distinction is not a footnote; it determines which findings apply to which molecule. The multi-day human pharmacokinetics — basal GH up roughly 7.5-fold, IGF-1 up about 45% a week out ^[3], and the 2- to 10-fold GH elevation sustained for six days or more ^[1] — were measured with the long-acting DAC form. None of those durations transfers to the short-acting no-DAC peptide, which clears in the native-GHRH range.

This matters because the popular literature constantly cross-applies them. A claim that "CJC-1295" elevates IGF-1 for nine to eleven days is true of the DAC form and false of Modified GRF (1-29). The preserved-pulsatility finding ^[3] was likewise a DAC-form result. When you read any CJC-1295 figure on this site or elsewhere, the first question is always which form it describes — and on this tracker, a multi-day figure is always the DAC form and a short-acting note is always the no-DAC one.

The program that did not advance

The long-acting DAC program has a halted-development history worth logging plainly. The original ConjuChem DAC program was discontinued; a Phase 2 trial in HIV-associated visceral obesity (NCT00267527) did not advance, and the long-acting DAC variant was not developed into an approved product. A patient death during the development era is frequently cited in connection with the halted program, though a causal link to CJC-1295 was not established in the public record. CJC-1295 is not approved for human use anywhere, in either form, and neither the DAC nor the no-DAC variant has a body of large efficacy or long-term safety data behind it.