CJC-1295 No DAC (Mod GRF 1-29)

Research-Grade

CJC-1295 without DAC, commonly known as Modified GRF (1-29) or Mod GRF 1-29, is a synthetic analog of the first 29 amino acids of human growth-hormone-releasing hormone (GHRH). Four amino acid substitutions at positions 2, 8, 15, and 27 protect the peptide from rapid enzymatic degradation by dipeptidyl peptidase IV (DPP-IV) and other serum proteases, extending its effective half-life from the 7-minute duration of native GHRH to approximately 30 minutes — long enough to produce a robust, discrete GH pulse but short enough to preserve the pulsatile pattern of natural GH secretion. The critical distinction from CJC-1295 with DAC is pharmacokinetic. The DAC (Drug Affinity Complex) version includes a maleimidopropionic acid linker that covalently binds serum albumin, extending the half-life to 6–8 days and producing continuous, non-pulsatile GH elevation. This tonic elevation does not replicate natural physiology and carries a higher risk of GH-axis downregulation and side effects (water retention, insulin resistance). The no-DAC version produces a sharp GH spike that resolves within 2–3 hours, closely matching the endogenous ultradian GH pulse rhythm. In clinical and practitioner settings, CJC-1295 no-DAC is almost always paired with a GHRP-class peptide (most commonly Ipamorelin) because GHRH and GHRP activate distinct receptor systems on the same pituitary somatotroph cell. This dual-receptor activation produces synergistic GH release substantially greater than either peptide alone. The combination has become the standard framework in peptide-based GH optimization protocols.