CJC-1295 DAC

The difference is one residue and one linker, and it changes the pharmacokinetics by orders of magnitude. CJC-1295 without DAC, also called modified GRF (1-29), is 29 residues, C₁₅₂H₂₅₂N₄₄O₄₂, 3367.9 g/mol, and is cleared within minutes. CJC-1295 with DAC adds Lys30 bearing 3-maleimidopropionic acid, taking the mass to 3647.2 g/mol, a difference of 279.3 corresponding exactly to the lysine plus the maleimidopropionyl group. That maleimide conjugates to albumin and gives the reported terminal half-life of roughly 6 to 8 days. The receptor and the binding site are the same; only the residence time differs.

DAC stands for Drug Affinity Complex. Chemically it is a maleimide, a Michael acceptor that reacts selectively with free sulfhydryl groups, and the most abundant free thiol in plasma is Cys34 of human serum albumin. The peptide therefore forms a stable covalent thioether bond to albumin after administration. This is a genuine covalent conjugation, not the reversible non-covalent albumin binding used by fatty-acid-acylated peptides, and it is why the effect on half-life is so large. Jetté and colleagues (Endocrinology, 2005) demonstrated the bioconjugation and identified CJC-1295 from a set of three maleimido GRF derivatives.

Teichman and colleagues (J Clin Endocrinol Metab, 2006) reported a terminal half-life of approximately 6 to 8 days in healthy adults following single administration, against a half-life of the order of minutes for unmodified GRF(1-29). The extension comes from albumin conjugation, which removes the peptide from renal filtration and gives a long-lived circulating depot. For comparison, the no-DAC modified GRF (1-29) form is generally quoted at around 30 minutes.

The published data say otherwise, and this is the most useful thing to know about the compound. Ionescu and Frohman (J Clin Endocrinol Metab, 2006) specifically examined whether continuous GHRH-receptor stimulation abolishes pulsatility and reported that pulsatile GH secretion persisted during continuous stimulation by CJC-1295. The implication is that GH pulse generation is not driven by GHRH pulse frequency alone, so the common framing of DAC as producing a non-physiological flat profile and no-DAC as the only pulsatile option is an oversimplification of the literature.

Yes, GHRH analogues and growth hormone secretagogues are routinely studied in combination because they act at different receptors. CJC-1295 DAC binds the GHRH receptor, while Ipamorelin is a selective agonist at GHS-R1a, the ghrelin receptor, and the two pathways converge on the somatotroph. Researchers designing such work should note that the DAC form's multi-day residence time makes the two compounds' pharmacokinetics very different, which matters for how a combined protocol is interpreted. No dosing guidance is offered here; all material is supplied for laboratory research only.

UK Peptide Lab supplies research-grade CJC-1295 DAC 5mg in the UK, batch UKPL-740 at 98.65% purity by HPLC on a supplier-reported analysis, with the certificate of analysis published on this product page and independent verification pending, and same-day UK dispatch on orders placed before 3pm UK time. Free UK Royal Mail Tracked shipping over £69. The no-DAC modified GRF (1-29) form is listed separately. Supplied for in-vitro laboratory research only, purchasers must be 18 or over.

Check the mass. CJC-1295 DAC is 3647.2 g/mol and the no-DAC modified GRF (1-29) is 3367.9 g/mol. A mass spectrometry result near 3368 on a vial sold as DAC means it holds the short-acting peptide. Our batch UKPL-740 showed [M+H]+ at 3648.2 m/z, matching the DAC form, with 98.65% purity by HPLC.

CJC-1295 DAC is used in preclinical endocrine research on GHRH receptor activation, somatotroph pharmacology and sustained versus pulsatile receptor stimulation. It is also a working example of albumin bioconjugation chemistry for extending peptide half-life.