CJC-1295 / DAC VS NO-DAC
CJC-1295 DAC vs no-DAC (Modified GRF 1-29): the half-life difference.
One molecule lasts days; the other lasts minutes to hours. They share a backbone and nearly a name, and conflating them is the single most common error about this compound. Here is the split, drawn as two decay curves.
Why DAC vs no-DAC is the question that matters
The single most-conflated point about this compound is that "CJC-1295" names two molecules with the same backbone but a ten-thousand-fold difference in duration. Both share the tetrasubstituted hGRF(1-29) sequence — the same four substitutions (D-Ala2, Gln8, Ala15, Leu27) that block dipeptidylpeptidase-IV cleavage [2]. The variable is one chemical feature: the albumin-binding DAC.
With the DAC, the peptide latches onto circulating serum albumin and persists for days, with an estimated half-life of 5.8 to 8.1 days in healthy adults [1]. Without it, the same sequence — Modified GRF 1-29 — clears in minutes to hours [1]. Everything downstream follows from that split: how long a single dose elevates GH, how IGF-1 behaves over the following weeks, and the entire logic of how the two forms were studied [1]. Reading any "CJC-1295" claim therefore starts with one question: DAC, or no-DAC? The rest of this page answers what each one is.
What is CJC-1295 with DAC?
DAC ("Drug Affinity Complex") is a maleimide chemistry that covalently links the peptide to circulating serum albumin, extending its plasma half-life toward that of albumin and giving CJC-1295 DAC a multi-day duration of action [2]. In practice a C-terminal lysine on the peptide carries a maleimidopropionyl handle that undergoes Michael addition with the free thiol on Cys34 of serum albumin, forming a stable peptide-albumin conjugate [2]. CJC-1295 DAC is therefore the albumin-conjugated, long-acting form of the tetrasubstituted GHRH(1-29) analog [2].
The albumin trick is the entire point of the molecule. Albumin is the most abundant protein in plasma and has a long natural residence time, so a peptide covalently bound to it inherits that longevity instead of being cleared on its own much faster schedule [2]. The original Endocrinology study that identified CJC-1295 confirmed that this conjugate still activates the GRF receptor on the anterior pituitary — duration was extended without abolishing the molecule's function [2].
What is CJC-1295 DAC?
CJC-1295 DAC is the albumin-conjugated, long-acting form of the tetrasubstituted GHRH(1-29) analog; in rats it raised GH area-under-the-curve 4-fold over the unconjugated peptide and remained detectable in plasma beyond 72 hours [2]. In healthy adults its estimated half-life is 5.8 to 8.1 days, with IGF-1 elevation persisting up to 28 days after multiple doses [1].
What 'no-DAC' (Modified GRF 1-29) means
"No-DAC" refers to the same tetrasubstituted GHRH(1-29) sequence without the albumin-binding DAC moiety — and removing that one feature collapses the duration from days to minutes-to-hours [1]. The four protease-resistant substitutions (D-Ala2, Gln8, Ala15, Leu27) remain, so the no-DAC peptide is still more stable than native GHRH against dipeptidylpeptidase-IV; but without albumin conjugation it clears at roughly the rate of native GHRH(1-29) [2]. The practical consequence is that no-DAC and DAC have entirely different dosing logic despite sharing a name and a backbone [1].
Modified GRF 1-29 (the no-DAC tetrasubstituted GHRH 1-29)
Modified GRF 1-29 is the most common name for the short-acting, no-DAC form, and the conflation between it and CJC-1295 DAC is the central caution of this page. Marketing and forums routinely use "CJC-1295" for both, but they are pharmacokinetically very different: the DAC conjugate persists for days while Modified GRF 1-29 acts over minutes to hours [1]. Anyone reading a "CJC-1295" claim should first establish which molecule is meant, because half-life, and therefore the entire kinetic profile, hinges on the presence or absence of the DAC [2]. The substitutions are identical; the albumin linker is the variable.
CJC-1295 half-life: 5.8-8.1 days (DAC) vs minutes-to-hours (no-DAC)
The half-life numbers anchor the entire DAC-versus-no-DAC contrast. The DAC variant's estimated half-life in healthy adults is 5.8 to 8.1 days, a duration that tracks albumin clearance because the peptide is covalently bound to it [1][2]. The no-DAC Modified GRF 1-29 sits in the minutes-to-hours range, reflecting native GHRH(1-29) kinetics modified only by the protease-resistant substitutions [1].
The DAC half-life has a downstream consequence worth stating precisely: in the human PK study, IGF-1 stayed above baseline for nine to eleven days after a single dose, and as long as 28 days after repeat dosing [1]. That is a hormonal effect outlasting the injection by weeks — a profile only the albumin conjugate produces. The no-DAC form, by contrast, delivers a brief GHRH-receptor stimulus that resolves within the same day [1].
This is the difference the decay comparator on this page renders: a long, slow violet curve for the DAC conjugate against a short, steep curve for the no-DAC form. The albumin bioconjugation is the whole story — the same receptor, the same backbone, but a duration measured in days versus one measured in hours [2]. The studied doses behind both profiles are documented under doses used in CJC-1295 research.
Why the conflation is more than pedantry
Treating DAC and no-DAC as interchangeable misreads the compound at the level that matters most. A claim, a study, or a stated half-life that is true for one form can be flatly wrong for the other [1]. The preserved-pulsatility and multi-day GH/IGF-1 findings this site documents were measured on the long-acting molecule in early human PK work [1][3]; they do not automatically describe a short-acting no-DAC peptide, which was never the subject of those particular studies.
The practical reading rule is simple. When a source says "CJC-1295," check whether it means the DAC conjugate (multi-day) or Modified GRF 1-29 (minutes-to-hours), because the kinetics, and therefore everything that depends on them, diverge completely [1][2]. Both remain unapproved research chemicals, and CJC-1295 is prohibited at all times in sport under WADA Section S2.