CJC-1295

CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH) that binds to the GHRH receptor on somatotroph cells in the anterior pituitary gland. Upon receptor activation, it stimulates the synthesis and pulsatile release of growth hormone (GH) into the bloodstream.

What distinguishes CJC-1295 from natural GHRH is its extended half-life. Through amino acid substitutions at positions 2, 8, 15, and 27 of the native GRF(1-29) sequence, CJC-1295 resists enzymatic degradation by dipeptidyl peptidase-IV (DPP-IV), which normally cleaves GHRH within minutes. Some formulations also incorporate Drug Affinity Complex (DAC) technology, which enables the peptide to bind to circulating albumin, further extending its duration of action to several days.

The resulting sustained GH elevation promotes downstream IGF-1 (Insulin-like Growth Factor-1) production in the liver, which mediates many of GH's anabolic, metabolic, and regenerative effects — including protein synthesis, fat oxidation, bone mineralisation, and tissue repair.

CJC-1295 was developed in the mid-2000s by ConjuChem Biotechnologies (now Conjuchem LLC) as a long-acting GHRH analogue designed to overcome the ultra-short half-life of endogenous GHRH. The original formulation with DAC (Drug Affinity Complex) showed dramatic increases in mean GH and IGF-1 levels in human trials.

A Phase II clinical trial published in 2006 demonstrated that a single subcutaneous injection of CJC-1295 DAC could elevate GH levels for 6-8 days and IGF-1 levels for up to 28 days. The no-DAC version (often called Mod GRF 1-29) has a shorter duration but remains one of the most studied GHRH analogues in peptide research, often combined with ghrelin mimetics like Ipamorelin for synergistic GH release.