CJC-1295 DAC vs No-DAC (Modified GRF 1-29) in the Research Literature

CJC-1295 DAC: the albumin-conjugated, multi-day form

CJC-1295 DAC is the long-acting species. The 'Drug Affinity Complex' modification adds a maleimidopropionyl (MPA) linker to a C-terminal lysine; that linker undergoes Michael addition with the free thiol on Cys34 of circulating serum albumin, forming a covalent peptide-albumin conjugate ^[2]. Because the effective circulating molecule is then roughly 66 kDa — albumin-sized — it clears at albumin's slow rate. In healthy adults the estimated half-life is 5.8-8.1 days, with IGF-1 elevation persisting up to 28 days after multiple doses ^[3].

This is the variant behind the headline human results: the days-long GH and IGF-1 elevation from a single dose ^[3], and the preserved-pulsatility finding ^[1]. In GHRH-knockout mice, 2 micrograms of CJC-1295 once every 24 hours fully normalized body weight and length, while dosing every 48-72 hours was progressively less effective ^[4] — direct evidence that the long-acting analog's duration is doing real work on a once-daily schedule.

CJC-1295 No-DAC (Modified GRF 1-29): Short-Acting by Design

CJC-1295 no DAC is the short-acting form, and the distinction is structural, not a matter of degree. The no-DAC variant keeps the four protease-resistant substitutions on the hGRF(1-29) backbone but omits the albumin-binding DAC moiety entirely. Without covalent albumin conjugation there is no extended circulating species, so clearance reverts to the minutes-to-hours range of native GHRH(1-29) — slowed by the substitutions, but nothing like the DAC form's multi-day persistence.

The practical consequence: the no-DAC form produces a brief GH pulse rather than a sustained elevation, and any schedule, route, or expectation drawn from the DAC pharmacokinetics does not transfer to it. Treating CJC-1295 DAC and no-DAC as interchangeable is the error this page exists to correct.

What 'Modified GRF (1-29)' Means

Modified GRF 1-29 is the common name for the no-DAC form. It is the tetrasubstituted GHRH(1-29) sequence — the first 29 amino acids of human GH-releasing factor with the four stabilizing substitutions — and nothing else. The name signals exactly what distinguishes it from CJC-1295 DAC: the modifications to the GRF(1-29) backbone are present, but the albumin handle is not. Marketing and forums routinely use 'CJC-1295' to mean Modified GRF 1-29 and vice versa; in the literature they are two compounds with different half-lives, and this digest keeps the labels precise.

Why the distinction is not pedantic

The DAC-versus-no-DAC split changes what every other number on this site means. A half-life of 5.8-8.1 days ^[3] implies dosing measured in days; a half-life of minutes-to-hours implies something entirely different. The published human results — the days-long GH and IGF-1 elevation ^[3], the preserved pulsatility ^[1], the once-daily growth normalization in GHRH-knockout mice ^[4] — were obtained with the long-acting analog, and they cannot simply be assigned to the short-acting form.

The practical risk is real: a reader who copies a 'CJC-1295' figure that actually describes the DAC variant onto the no-DAC form, or vice versa, has mismatched the schedule to the pharmacokinetics. The development record adds its own caution. The original long-acting DAC program (ConjuChem) was discontinued; a patient death during the development era is frequently cited in connection with the halted Phase 2 trial, though a causal link to CJC-1295 was not established in the public record. Whatever weight one gives that, it is one more reason the two variants deserve separate, clearly-labeled treatment rather than a single blurred 'CJC-1295.'

What is CJC-1295 with DAC?

The 'Drug Affinity Complex' variant carries a maleimidopropionyl linker that covalently binds the free thiol of circulating serum albumin, extending the plasma half-life toward that of albumin itself and giving CJC-1295 DAC its multi-day duration ^[2]. The result is the days-long GH and IGF-1 elevation seen after a single dose in healthy adults ^[3].

What is CJC-1295 DAC?

CJC-1295 DAC is the albumin-conjugated, long-acting form of the tetrasubstituted GHRH(1-29) analog. In healthy adults it elevated GH and IGF-1 for days, with an estimated half-life of 5.8-8.1 days ^[3]. It is the variant behind essentially all of the published human CJC-1295 pharmacokinetic data.

How much CJC-1295 DAC should I take?

Human pharmacokinetic work on the DAC variant used single subcutaneous doses of 30-90 micrograms/kg ^[3]. Because the DAC half-life is 5.8-8.1 days, its dosing schedule differs fundamentally from the short-acting no-DAC form. No clinical dosing is established for healthy adults, and this digest reports research doses only — it makes no human-use recommendation.