CJC-1295 without DAC, commonly catalogued as modified GRF(1-29), is a synthetic analog of the first twenty nine residues of growth hormone releasing hormone, carrying substitutions that resist dipeptidyl peptidase 4 cleavage and trypsin like clipping. Ipamorelin, CAS 170851-70-4, is not a GHRH analog at all. It is a synthetic secretagogue acting at the growth hormone secretagogue receptor, the same receptor engaged by ghrelin, and it was designed for selectivity rather than raw potency.
Structurally the two are nothing alike. Ipamorelin is recorded as C38H49N9O5 with an average mass of 711.85 and the sequence H-Aib-His-D-2-Nal-D-Phe-Lys-NH2, a short chain containing one non proteinogenic residue, aminoisobutyric acid, plus two D configured residues, all of which make it a poor substrate for proteases. Molecular values for the combined vial are not recorded in our molecular dataset, since a mixture has no single formula, so the GHRH analog component is described here by class. That component is by far the larger of the two.
The DAC question is the most common source of confusion. DAC stands for drug affinity complex, a maleimide bearing linker attached to the peptide so that it forms a covalent bond with circulating albumin. A GHRH analog carrying that linker persists far longer in plasma in published animal work and produces a sustained elevation rather than a pulse. The no DAC version lacks the linker entirely and is cleared quickly, which in pituitary and rodent studies produces a short pulse closer to the natural secretion pattern. Blends are built with the no DAC version because a pulsatile design is the point of them.
The rationale for combining the two is receptor arithmetic. A GHRH analog acts through a G protein coupled receptor that raises cyclic AMP inside the somatotroph. A ghrelin receptor agonist acts through a different G protein coupled receptor that mobilises intracellular calcium through phospholipase C, and in some published models it also reduces somatostatin tone. Because the two routes converge on the same secretory cell from different directions, studies in pituitary cell culture report a combined release larger than either compound produces alone. Ipamorelin is favoured over older secretagogues in these designs because published work reports little accompanying release of prolactin or corticotropin at comparable exposures.
Handling is comparable for both. Each is a lyophilized powder held at minus 20 degrees Celsius protected from light and moisture, reconstituted with gentle swirling rather than shaking, refrigerated at 2 to 8 degrees Celsius once in solution, and aliquoted against repeated freeze thaw. The blend vial carries one additional constraint, which is that the two components cannot be separated after reconstitution, so any experiment that needs to vary one against the other requires single component vials.
Selection follows the design of the experiment. Isolating the GHRH receptor arm calls for the analog alone. Isolating the ghrelin receptor arm calls for ipamorelin alone. Asking whether the two are additive or synergistic calls for all three preparations run in parallel. What remains unsettled is how much of the synergy reported in cell models carries over to intact animals, where somatostatin tone and receptor desensitisation both intervene.