What is the difference between CJC-1295 and CJC-1295 DAC?

CJC-1295 is a synthetic GHRH-analogue that was engineered in two structurally distinct forms. The 'No DAC' variant (sometimes called modified GRF 1-29) is a shorter-half-life compound with pharmacology closer to native pulsatile GHRH signalling. The 'DAC' variant (Drug Affinity Complex) incorporates additional maleimide chemistry that covalently binds to serum albumin, dramatically extending half-life to about a week.

The pharmacological consequences are significant. CJC-1295 No DAC produces brief peaks of GHRH-receptor signalling that mimic the native pulsatile pattern of hypothalamic GHRH release, preserving somatotroph responsiveness. CJC-1295 DAC produces sustained GHRH-receptor signalling with much smaller peak-to-trough excursion. Sustained receptor activation in this system can produce partial receptor desensitisation and continuously-elevated (rather than pulsatile) IGF-1 output.

For GH-secretagogue applications where preserved pulsatility is desirable, CJC-1295 No DAC is generally preferred, often paired with Ipamorelin to add the ghrelin-receptor arm. For contexts where continuous elevated IGF-1 output is the goal and pulsatility is not required, CJC-1295 DAC may be chosen. In practice, the No DAC variant sees more use in the peptide-therapy space because pulsatile-pattern preservation matches the physiology most users are trying to support.

Teichman 2006 characterised the extended half-life of the DAC variant in first-in-human studies.