CJC-1295 DAC

CJC-1295 DAC (Drug Affinity Complex) is a long-acting synthetic analog of growth hormone-releasing hormone (GHRH), developed by ConjuChem Biotechnologies. It was engineered to address the primary limitation of native GHRH and its earlier analogs: rapid degradation by dipeptidyl peptidase IV (DPP-IV), which gives natural GHRH a half-life of only 7 minutes in the circulation. CJC-1295 DAC resolves this through two complementary modifications: four amino acid substitutions that render the peptide backbone resistant to DPP-IV cleavage, and the attachment of a Drug Affinity Complex (DAC) molecule that enables covalent binding to circulating serum albumin after injection.

The albumin-binding mechanism is the defining pharmacological feature of the DAC formulation. Once CJC-1295 DAC is injected subcutaneously, the DAC moiety undergoes a bioconjugation reaction with endogenous albumin through a maleimide-thiol linkage. Because albumin has a circulating half-life of approximately 19 days, the conjugated peptide is effectively shielded from renal clearance and proteolytic degradation, extending the functional half-life of CJC-1295 DAC to 6 to 8 days in humans. This is in marked contrast to CJC-1295 without DAC (also called Modified GRF 1-29), which has a half-life of approximately 30 minutes.

The clinical pharmacology of CJC-1295 DAC was characterized in a Phase II human study published in the Journal of Clinical Endocrinology and Metabolism (2006). After a single subcutaneous injection in healthy adults, mean plasma GH concentrations increased 2- to 10-fold and remained elevated for 6 days or more, depending on dose. Mean plasma IGF-1 concentrations rose 1.5- to 3-fold and remained elevated for 9 to 11 days. Critically, pulsatility of GH secretion was preserved throughout the sustained stimulation period, a physiologically important finding that distinguishes CJC-1295 DAC from exogenous GH administration. Multiple-dose studies demonstrated cumulative IGF-1 elevation, with levels remaining elevated for up to 28 days following a series of weekly injections.

Sustained GHRH receptor stimulation from long-acting analogs like CJC-1295 DAC is sometimes described as producing a 'GH bleed' effect: a continuous low-level elevation of GH between pulsatile peaks, rather than the sharp pulsatile pattern of native GH secretion. Research applications have focused on aging-related GH decline, body composition, sleep quality, and recovery. CJC-1295 DAC is not FDA-approved for any indication and remains a research compound. It is frequently used in combination with GHRP-class peptides or ghrelin mimetics such as ipamorelin or MK-677 to produce synergistic GH release through complementary pituitary pathways.