CJC-1295 with DAC: GHRH Analog Research, Drug Affinity Complex & Purity Guide

For CJC-1295 with DAC sourcing and research context, review the CJC-1295 DAC research peptide page. CJC-1295 with DAC is a synthetic growth hormone-releasing hormone (GHRH) analog distinguished by two features: four amino acid substitutions that improve metabolic stability, and a Drug Affinity Complex (DAC) modification that enables albumin binding and dramatically extends plasma half-life. The result is a GHRH analog that behaves nothing like native GHRH(1-29), which has a half-life measured in minutes. CJC-1295 with DAC maintains bioactivity for several days after a single dose in rodent models — a pharmacokinetic profile that creates entirely different research possibilities and requires entirely different handling and documentation practices.

GHRH Biology and the Case for Analogs

Growth hormone-releasing hormone is a 44-amino-acid peptide secreted by the hypothalamus that stimulates GH release from pituitary somatotrophs. The biologically active portion is contained within the first 29 residues — GHRH(1-29) — which is why early synthetic GHRH analogs focused on that fragment. The problem with native GHRH(1-29) as a research tool is its rapid degradation: plasma dipeptidyl peptidase IV (DPP-IV) cleaves the His-Ala bond at positions 2-3 within minutes of administration, rendering it unsuitable for experiments requiring sustained GH stimulation.

CJC-1295 was developed to solve this problem. The four amino acid substitutions — Ala2 to Aib (DPP-IV protection), Gln8 to Ala (stability), Ala15 to Aib (stability), Leu27 to Arg (receptor binding optimization) — collectively extend the half-life from minutes to approximately 30 minutes for the base compound without DAC. The DAC modification extends it further still, to days.

The Drug Affinity Complex: How It Works

The DAC modification is a maleimide-lysine group attached to the epsilon-amino group of a lysine residue within the peptide sequence. Maleimide groups react specifically with the free thiol group of Cys-34 in human serum albumin — the most abundant plasma protein. This covalent albumin binding is what produces the extended half-life.

Once CJC-1295 with DAC binds albumin, the albumin-peptide complex circulates with the same half-life as albumin itself — approximately 19 days in humans. The GHRH receptor binding site on the peptide remains accessible despite the albumin attachment, so the compound can still stimulate pituitary GHS receptor signaling while circulating bound to albumin. The net effect is a compound that produces sustained, low-level GHRH receptor stimulation over multiple days from a single administration.

Jetté et al. (2005) documented this mechanism in detail, showing that the albumin-binding reaction was specific to Cys-34 and that the resulting complex retained GHRH receptor activity. This paper is the primary reference for understanding why CJC-1295 with DAC behaves so differently from both native GHRH and the without-DAC analog.

CJC-1295 With DAC vs Without DAC: Research Design Implications

The distinction between CJC-1295 with DAC and without DAC (also called Modified GRF 1-29 or CJC-1295 without DAC) is not a minor formulation difference — it represents fundamentally different pharmacokinetic paradigms with distinct experimental applications.

Without DAC, the compound has a half-life of 30-45 minutes. It produces a discrete GH pulse within an hour of administration and then clears. This makes it useful for studying acute pituitary responses, examining the relationship between GHRH receptor stimulation and GH pulse amplitude, or for experiments where controlled dosing intervals are required.

With DAC, GH elevation is sustained over multiple days. This is useful for studying the downstream consequences of prolonged GH elevation — IGF-1 production kinetics, changes in body composition over longer time periods, and experiments where consistent GH background is more important than pulsatility. It is also logistically simpler for multi-day animal studies, requiring less frequent dosing.

The choice between the two depends entirely on the research question. Researchers studying pulsatility, acute GH responses, or dose-response curves typically use the without-DAC version. Researchers studying downstream metabolic effects over longer periods typically prefer the with-DAC version. Receiving the wrong one is a meaningful experimental error, not a minor inconvenience.

COA Verification: The DAC Moiety Matters

Standard peptide COA verification checks HPLC purity and molecular weight. For CJC-1295 with DAC, this standard is necessary but not sufficient. The DAC moiety must be verified as correctly attached and chemically intact. A COA that confirms the peptide sequence without addressing DAC integrity is leaving the most pharmacologically critical modification unconfirmed.

The correct molecular weight for CJC-1295 with DAC is approximately 3647.28 g/mol — significantly higher than the without-DAC form (~3367.15 g/mol). If mass spectrometry confirms a value in the 3367 range rather than 3647, you have received the without-DAC version regardless of what the label says. This is not a theoretical risk; it has been documented in the research literature examining compound identity in the commercial peptide market.

The maleimide group in the DAC modification can also hydrolyze slowly under aqueous conditions, converting to a maleamic acid form that cannot bind albumin. For this reason, reconstituted CJC-1295 with DAC should be used promptly and not stored as a solution for extended periods. The hydrolysis is slow and may not be detectable by standard HPLC, but it progressively reduces the proportion of albumin-binding-competent compound in the preparation.

Storage and Handling

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Before reconstituting, use the Peptide calculator to standardize your preparation math.

Store lyophilized CJC-1295 with DAC at −20°C, sealed, protected from light and moisture. The maleimide group is stable in lyophilized form — moisture is the primary concern, as even atmospheric humidity can initiate the slow hydrolysis described above. Under proper dry conditions, lyophilized CJC-1295 with DAC maintains stability for 24 months.

Reconstitute with bacteriostatic water. The compound dissolves at typical research concentrations without difficulty despite its larger size (~3.6 kDa). Inject water down the vial wall, swirl gently. Use reconstituted solution promptly. If your protocol requires preparation in advance, prepare the smallest volume needed for each experimental run rather than preparing a bulk solution with extended storage time.

Key Research Citations

• Jetté L, Léger R, Thibaudeau K, et al. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-acting GRF analog. Endocrinology. 2005;146(7):3052-3058. doi:10.1210/en.2004-1286
• Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006;91(12):4792-4797. doi:10.1210/jc.2006-1702
• Semenistaya EN, Zvereva IE, Krotov GI, Rodchenkov GM. Determination of CJC-1295, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin in human blood serum by high-resolution mass spectrometry. Drug Test Anal. 2016;8(7):659-668. doi:10.1002/dta.1831