The compound forms
DAC and no DAC: two forms of CJC-1295
The mouse growth experiment and the early human hormone studies used the long-acting design. The familiar no-DAC name introduces a chemically important difference.
Albumin conjugation
Jette and colleagues’ rat and laboratory study examined GHRH analogs designed to bind to serum albumin. CJC-1295 combined four stabilizing substitutions with the added albumin-binding part called DAC, short for Drug Affinity Complex. The bond is covalent: the peptide becomes chemically attached to the protein.
In rats, the albumin-bound design produced a 4-fold increase in growth hormone exposure over 2 hours compared with unconjugated hGRF(1-29), and the peptide remained detectable in plasma beyond 72 hours. The laboratory work also found increased resistance to breakdown by DPP-IV, an enzyme that cuts peptides.
I admire that albumin attachment. It gave a fragile signal a much longer presence in blood. That success explains the interest in the compound without settling the question of lasting human benefit.
Modified GRF 1-29, the no-DAC form
Modified GRF 1-29 carries the four stabilizing changes but lacks the albumin-binding part. Its action is short, in the minutes-to-hours range described in the research account, compared with days for the DAC form. The albumin-conjugate experiments explain why removing that attachment changes the interpretation so much.
An unnamed form is enough to spoil a duration claim for me. “CJC-1295” alone can conceal that omission. Chemical listings have also applied identifiers inconsistently and disagreed about formula and molecular weight; a familiar registry number cannot resolve an ambiguous description.
CJC-1295 half-life in people
The healthy-adult study’s estimate was 5.8-8.1 days for CJC-1295 DAC. Half-life describes the time for the drug concentration to fall by half. The same study found IGF-1 elevation lasting 9-11 days after single administrations and up to 28 days after multiple administrations.
Those are different measurements: the drug’s persistence and the duration of a downstream hormone response. I prefer seeing them together because a half-life figure alone leaves out what the hormone system did during that interval. Neither figure establishes an approved treatment schedule. The study amounts and human results provide the rest of that experimental context.