CJC-1295 with DAC (DAC:GRF) is a long-acting injectable synthetic analogue of growth hormone-releasing hormone (GHRH), developed by ConjuChem. It is based on a GHRH(1-29) fragment with four amino-acid substitutions (positions 2, 8, 15, 27) that resist the DPP-4 enzyme. The defining feature of the DAC version: a lysine bearing a maleimidopropionyl group (the "DAC") is attached to the C-terminus, and after injection it covalently binds to blood albumin.
Mechanism of Action
CJC-1295 activates GHRH receptors on somatotroph cells of the anterior pituitary, stimulating release of the body's own growth hormone (GH) and, in turn, insulin-like growth factor 1 (IGF-1); with prolonged use it even raises GH mRNA levels and promotes proliferation of the somatotroph cells themselves. The key to its long action is DAC: the maleimide group on the C-terminal lysine covalently bonds, after subcutaneous injection, to the free thiol of cysteine-34 on blood albumin. This protects the peptide from degradation and largely prevents renal clearance, extending the half-life from ~30 minutes (in the no-DAC form) to roughly 6–8 days (estimated 5.8–8.1 days). Importantly, CJC-1295 does not deliver growth hormone directly — it only prompts the pituitary to produce its own. So, despite the peptide's constant presence, the pituitary still releases GH in pulses: in the Ionescu and Frohman (2006) study, the rhythm and frequency of pulses were preserved under continuous stimulation (maintained by the inhibitory hormone somatostatin), although the baseline GH level between pulses rose. In other words it is 'pulses on a raised baseline,' not the flat continuous flood produced by injecting GH itself. Only the GH/IGF-1 axis is selectively raised — levels of other pituitary hormones (prolactin, cortisol, ACTH) do not increase.
Effects in Research
In a clinical study in healthy adults (Teichman et al., 2006), a single subcutaneous injection raised GH 2–10-fold for more than 6 days and IGF-1 1.5–3-fold for 9–11 days; with repeated dosing, mean IGF-1 stayed above baseline for up to 28 days. In GHRH-knockout mice, daily administration normalized growth and body composition. Through its effect on the GH/IGF-1 axis, CJC-1295 is studied across a broad range of areas: growth hormone deficiency (growth and body composition — more muscle, less fat); anti-aging effects (bone density, muscle strength, collagen synthesis and skin firmness); sports medicine and recovery (muscle repair, tissue healing); and metabolism (fat breakdown, insulin sensitivity). The compound reached Phase II clinical trials (including for visceral obesity in HIV patients) but development was discontinued in 2006. GHRH analogues are on the WADA prohibited list.
Properties
White lyophilized powder, soluble in water. It is a tetrasubstituted GHRH(1-29) with a C-terminal lysine modified by Nε-maleimidopropionyl (DAC). Formula C₁₆₅H₂₆₉N₄₇O₄₆, molecular weight ≈3647.9 Da. CAS 863288-34-0.
Storage
Store the lyophilized powder at 2–8°C in a dry place protected from light; for long-term storage −20°C is optimal. After reconstitution keep refrigerated, do not freeze, and use within a few weeks.
BIOLABCHEMICALS