CJC-1295 (no DAC) is a modified GHRH(1–29) analogue with a half-life of approximately 30 minutes to 2 hours, producing physiological pulsatile GH release; CJC-1295 DAC adds a maleimido-propionic acid Drug Affinity Complex (DAC) that covalently binds circulating serum albumin, extending half-life to approximately 6–8 days and converting pulsatile GH stimulation to a sustained continuous pattern.
Research reference only — all information on this page summarises peer-reviewed scientific literature and does not constitute medical advice. View full compound profiles: CJC-1295 · CJC-1295 DAC
Mechanism Comparison
Both compounds share the same modified GHRH(1–29) peptide backbone: a synthetic analogue incorporating four amino acid substitutions (Ala²→D-Ala, Gln⁸→Ala, Ala¹⁵→Ala, Leu²⁷→Arg) that increase resistance to proteolytic degradation compared to native sermorelin. CJC-1295 without DAC (also marketed as "Modified GRF(1–29)") retains this moderate stability but is still subject to plasma clearance with a half-life of 30 minutes to 2 hours, producing GH pulses that resolve within hours. CJC-1295 DAC incorporates an additional maleimido-propionic acid (MPA) group attached via a lysine residue, which forms a stable thioether bond with cysteine-34 on circulating human serum albumin (HSA). Since albumin has a plasma half-life of ~19 days, the resulting CJC-1295 DAC–albumin complex circulates for approximately 6–8 days, continuously stimulating GHRHR and producing sustained, non-pulsatile GH elevation. This pharmacokinetic distinction — pulsatile vs. continuous GH secretion — is the primary research consideration when selecting between these two compounds.
Side-by-Side Attributes
| Attribute | CJC-1295 | CJC-1295 DAC |
|---|---|---|
| DAC modification | None — "no DAC" / Modified GRF(1–29) | Maleimido-propionic acid → covalent albumin binding |
| CAS number | 863288-34-0 | 863288-34-0 (base) + DAC modification |
| Plasma half-life | ~30 min – 2 hours | ~6–8 days (albumin-bound) |
| GH secretion pattern | Pulsatile — mimics physiological GH pulse | Sustained continuous — non-pulsatile GH elevation |
| GH axis feedback | Normal — somatostatin feedback intact between pulses | Attenuated — continuous stimulation may blunt feedback loop |
| IGF-1 elevation | Moderate; follows GH pulse kinetics | Higher sustained IGF-1 (confirmed in Walker et al., 2006 Phase 2 trial) |
| Dosing frequency | Daily to several times per week (pulsatile protocol) | Once weekly to once per 2 weeks (sustained protocol) |
| Research published | Limited dedicated CJC-1295 no-DAC trials; extrapolated from sermorelin | Phase 2 RCT (Walker et al., JCE&M, 2006; n=65) |
Key Research Points
- 1The DAC technology (Drug Affinity Complex) used in CJC-1295 DAC was developed specifically to leverage the long plasma half-life of serum albumin (~19 days). The maleimide group on the DAC reacts selectively with the free thiol of Cys³⁴ on albumin in a Michael addition reaction, producing a stable thioether conjugate that circulates for 6–8 days.
- 2Walker et al. (J Clin Endocrinol Metab, 2006) conducted the primary Phase 2 trial of CJC-1295 DAC (n=65, healthy adults). Single doses produced dose-dependent increases in mean GH AUC over 6 days and sustained IGF-1 elevation of 30–70% above baseline over 7–28 days — with a single 2 mg dose maintaining IGF-1 elevation for up to 28 days in some subjects.
- 3The key pharmacological debate in GH secretagogue research concerns pulsatile vs. continuous GH patterns. Physiological GH is secreted in pulses (primarily during slow-wave sleep), and this pulsatility is important for GH's anabolic signalling specificity. Continuous GH stimulation (as with CJC-1295 DAC) may produce higher average GH/IGF-1 levels but potentially blunt the receptor responsiveness that pulsatile delivery preserves.
- 4CJC-1295 no-DAC (Modified GRF 1–29) is frequently combined with a GHS-R1a agonist (such as ipamorelin) in research protocols studying synergistic GH release — the GHRHR and GHS-R1a receptors are functionally distinct and their concurrent activation produces greater GH secretion than either alone.
- 5Neither CJC-1295 no-DAC nor CJC-1295 DAC has obtained FDA or EMA approval. Both remain investigational research compounds. CJC-1295 DAC is among the more pharmacologically characterised GHRH analogues in the research literature, with the 2006 Walker et al. Phase 2 data providing a unique human clinical reference dataset.
Frequently Asked Questions
What is the difference between CJC-1295 and CJC-1295 DAC?
CJC-1295 without DAC (also called Modified GRF 1–29) is a modified GHRH(1–29) analogue with a plasma half-life of approximately 30 minutes to 2 hours, producing short, pulsatile growth hormone stimulation similar to endogenous GHRH. CJC-1295 with DAC (Drug Affinity Complex) adds a maleimide group that covalently bonds to serum albumin in the bloodstream, extending the half-life to approximately 6–8 days and converting pulsatile GH release into sustained, continuous GH elevation. The choice between them in research depends on whether the protocol requires physiological pulsatile GH kinetics (no DAC) or sustained GH axis activation (DAC).
What does DAC stand for in CJC-1295 DAC?
DAC stands for Drug Affinity Complex — a chemical modification technology developed to extend peptide half-life by enabling covalent binding to circulating serum albumin. In CJC-1295 DAC, the DAC consists of a maleimido-propionic acid group attached to a lysine residue on the peptide. Once administered, the maleimide group reacts with the free thiol (–SH) of cysteine-34 on human serum albumin (HSA) via a Michael addition, forming a stable thioether bond. Since albumin has a plasma half-life of approximately 19 days, the CJC-1295 DAC–albumin complex circulates for approximately 6–8 days, continuously stimulating GHRH receptors on pituitary somatotrophs.
What did the CJC-1295 DAC clinical trial show?
Walker et al. (Journal of Clinical Endocrinology & Metabolism, 2006) conducted a double-blind, placebo-controlled Phase 2 trial of CJC-1295 DAC (n=65 healthy adults aged 21–61). Single subcutaneous doses of 30, 60, 90, or 120 µg/kg produced dose-dependent increases in mean GH AUC over the following 6 days (up to 8-fold increase vs placebo) and significant IGF-1 elevations of 30–70% above baseline sustained over 7–28 days. These findings established that a single GHRH analogue injection could produce multi-week IGF-1 elevation in healthy humans — a pharmacokinetic profile previously unachievable with native GHRH or sermorelin.
Deep Dive
For extended mechanism analysis, trial data, and regulatory context, see the full research article:
CJC-1295 Research Guide: Mechanism, DAC vs No-DAC, and GH Axis Biology →Full compound profile
CJC-1295
Full compound profile
CJC-1295 DAC