CJC-1295 with DAC is a tetrasubstituted analog of human growth hormone-releasing factor hGRF(1-29) carrying a Drug Affinity Complex — a maleimidopropionic acid linker that forms a covalent bond with cysteine-34 of circulating albumin after administration. That single structural addition is the entire difference between the two CJC-1295 variants sold for research: it extends the reported half-life from minutes to roughly 6–8 days (Teichman et al., JCEM, 2006), which is why the DAC form is the variant used in studies of prolonged, non-pulsatile GHRH receptor stimulation. This article is for laboratory research use only.
What DAC Actually Is
DAC stands for Drug Affinity Complex, a bioconjugation platform originally developed by ConjuChem. The chemistry is straightforward: a maleimide group is attached to the peptide, and maleimides react selectively with free thiols. Human serum albumin has exactly one free cysteine thiol available in circulation — Cys34 — so the linker reacts there and essentially nowhere else. The result is a covalent peptide-albumin conjugate formed in vivo, after injection, rather than a pre-formed fusion protein.
Because albumin has a circulating half-life measured in weeks and is largely spared from renal clearance, anything covalently attached to it inherits much of that persistence. Jetté and colleagues (Endocrinology, 2005) screened a series of hGRF(1-29)-albumin bioconjugates for GRF-receptor activation on rat anterior pituitary and identified CJC-1295 as the long-lasting lead from that series.
The same platform was applied to other peptides. CJC-1131, a GLP-1(7-36) albumin bioconjugate described in Bioorganic & Medicinal Chemistry Letters in 2004, used identical chemistry to stabilize a peptide that is otherwise degraded within minutes by DPP-4. Researchers comparing half-life extension strategies often look at the two together, since they isolate the effect of the linker across two unrelated peptide backbones.
The Four Amino Acid Substitutions
The peptide backbone in CJC-1295 is not native GHRH. Four substitutions are made to the hGRF(1-29) sequence:
- D-Ala at position 2 — blocks DPP-4 cleavage, the primary route of native GHRH degradation
- Gln at position 8 — reduces asparagine deamidation
- Ala at position 15 — improves bioactivity
- Leu at position 27 — prevents methionine oxidation
Published Research Findings
Human Pharmacokinetic and Pharmacodynamic Data
Teichman et al. (Journal of Clinical Endocrinology & Metabolism, 2006) ran two randomized, placebo-controlled, double-blind ascending-dose trials in healthy adults aged 21–61, over 28 and 49 days. Single administrations produced 2- to 10-fold increases in plasma GH sustained for six days or more, and 1.5- to 3-fold increases in IGF-1 lasting 9–11 days. The reported half-life was 5.8–8.1 days. This remains the most frequently cited pharmacokinetic reference for the compound and the source of the "weekly dosing interval" figure that circulates in secondary literature.
Pulsatility Is Preserved, Not Flattened
A reasonable prediction would be that continuous GHRH-receptor stimulation collapses the normal pulsatile GH rhythm. Ionescu and Frohman (JCEM, 2006) tested this directly and found the opposite. Under continuous stimulation by CJC-1295, the frequency and magnitude of GH secretory pulses were unaltered. What changed was the baseline: trough GH rose approximately 7.5-fold, mean GH rose 46%, and IGF-1 rose 45%.
This is a mechanistically interesting result. It suggests the pulse generator upstream of the pituitary — driven by hypothalamic somatostatin withdrawal — continues to operate independently of ambient GHRH-receptor occupancy. For researchers studying GH-axis feedback architecture, that dissociation between basal tone and pulse generation is the main reason the DAC variant is used as a tool compound.
Animal Model Work
Alba et al. (American Journal of Physiology: Endocrinology and Metabolism, 2006) administered CJC-1295 once daily to GHRH knockout mice, a model with a defined and complete loss of endogenous GHRH signaling. Once-daily administration normalized growth in these animals, providing a clean demonstration that the analog engages the GHRH receptor functionally rather than merely elevating an assay readout.
Downstream Proteomic Effects
Sackmann-Sala et al. (Growth Hormone & IGF Research, 2009, 19(6):471-477) took a proteomic approach, comparing serum from 11 healthy young adult men before and one week after CJC-1295 administration using two-dimensional gel electrophoresis with mass spectrometry identification. Two spots decreased — an apolipoprotein A1 isoform and a transthyretin isoform — while beta-hemoglobin, a C-terminal albumin fragment, and a mixed immunoglobulin/albumin fragment spot increased. A linear relationship was observed between the immunoglobulin/albumin fragment spot and IGF-1 levels. This study is useful primarily as an example of untargeted downstream readouts in GH-axis research.
CJC-1295 With DAC vs. Without DAC
| Property | With DAC | Without DAC (Mod GRF 1-29) |
|---|---|---|
| Albumin conjugation | Yes, covalent via Cys34 | No |
| Reported half-life | 5.8–8.1 days | Approximately 30 minutes |
| Stimulation pattern | Continuous elevation of basal GH | Discrete, short-duration pulse |
| Typical research use | Sustained-exposure and chronic-axis studies | Acute pulse-response and secretagogue-synergy studies |
| Four backbone substitutions | Present | Present |
The two are not interchangeable in experimental design. A protocol built around a discrete GH pulse — for example, testing synergy with a GHRP such as ipamorelin or GHRP-6 — is measuring something the DAC variant cannot produce, because the DAC variant raises trough concentrations continuously. Conversely, questions about chronic GH/IGF-1 axis exposure cannot be answered with a compound cleared in half an hour.
Analytical Detection and Identity
Because CJC-1295 circulates bound to albumin, detecting it in biological matrices is not trivial — the analyte is a large conjugate present at low concentration. A 2021 review in Drug Testing and Analysis surveyed the state of GHRH-analog detection and noted that despite intelligence indicating use, synthetic GHRH analogs had not been reported in WADA-accredited laboratory samples, attributed to low urinary concentrations and incomplete knowledge of their metabolism.
That gap was addressed by Thomas et al. (Drug Testing and Analysis, 2022), who developed an antibody-free, ultrafiltration-based nanoLC-HRMS/MS assay for GHRH analogs in urine with limits of detection between 5 and 25 pg/mL and limits of identification between 25 and 50 pg/mL. For a research lab, these methods are relevant chiefly as reference procedures for confirming compound identity and characterizing degradation products.
A separate 2011 case report in Drug Testing and Analysis documented the identification of CJC-1295 in an unlabeled pharmaceutical preparation — a reminder that analytical confirmation of identity, not just vendor labeling, is what establishes what is actually in a vial.
2026 Context
A critical review published in July 2026 (Coutinho et al., The Journal of Sports Medicine and Physical Fitness, 66(7):880-885) examined the broader shift from anabolic-androgenic steroids toward peptides and peptide analogs, naming GHRH analogs including CJC-1295 and sermorelin among the compounds most widely encountered. The authors' conclusion is worth stating plainly: these remain experimental substances with poorly defined long-term risks, and the available longitudinal safety data are inadequate. Nothing in the published literature supports use outside a controlled laboratory setting.
It is also relevant that clinical development of CJC-1295 did not continue. A trial in HIV patients with visceral obesity (NCT00267527) is on record, but the compound never advanced to approval and has no marketing authorization in any jurisdiction. Its current status is that of a research tool compound.
Storage and Handling
CJC-1295 with DAC is supplied as a lyophilized powder. Standard handling for GHRH analogs applies:
- Store lyophilized material at -20°C or below, protected from light and moisture
- Reconstitute immediately before use with a sterile solvent appropriate to the protocol
- Avoid repeated freeze-thaw cycles, which degrade peptide integrity
- Handle in an appropriately equipped laboratory under standard safety procedures
Frequently Asked Questions
What does DAC stand for in CJC-1295 with DAC?
Drug Affinity Complex — a maleimidopropionic acid linker that forms a covalent bond with cysteine-34 of endogenous albumin after administration, extending the peptide's circulating half-life.
What is the reported half-life of CJC-1295 with DAC?
Teichman et al. (JCEM, 2006) reported 5.8 to 8.1 days in healthy adults. The non-DAC variant is cleared in roughly 30 minutes.
Does CJC-1295 with DAC eliminate the natural GH pulse?
No. Ionescu and Frohman (JCEM, 2006) found pulse frequency and magnitude unchanged; trough GH increased approximately 7.5-fold while pulsatility was preserved.
Is CJC-1295 with DAC the same compound as Mod GRF 1-29?
No. Mod GRF 1-29 is the tetrasubstituted hGRF(1-29) backbone without the DAC linker. Both share the same four amino acid substitutions, but only the DAC version conjugates to albumin.
Is CJC-1295 an approved drug?
No. It has no marketing authorization in any jurisdiction. Clinical development did not proceed past early trials, and it is supplied strictly for laboratory research use.
What purity does Dynamite Research Peptides provide?
99%+ purity, with a Certificate of Analysis available for every batch, verified by HPLC and mass spectrometry.
Summary
CJC-1295 with DAC is a GHRH analog whose defining feature is a maleimide linker that covalently binds albumin in vivo, producing a reported 5.8–8.1 day half-life against roughly 30 minutes for the non-DAC form. Published human work documents 2–10 fold GH elevation for six or more days and 1.5–3 fold IGF-1 elevation for 9–11 days, with GH pulsatility preserved rather than suppressed. Animal work in GHRH knockout mice confirms functional receptor engagement. The compound was never approved and remains an experimental tool.
All products are for research use only — not for human or animal consumption. Nothing in this article should be interpreted as medical advice or as a recommendation for use in humans or animals.