This article is provided for educational and informational purposes only. All compounds discussed are supplied strictly for laboratory and research use. Vitro Labs products are not for human or animal consumption.
CJC-1295 has two faces in the research literature, and the difference between them is one small chemical handle that changes almost everything about how the molecule behaves.
The version with DAC (Drug Affinity Complex) carries a maleimidopropionic acid linker that latches onto albumin, the most abundant protein in blood. Once attached, the compound rides around for days instead of minutes. The version without DAC. sometimes called Modified GRF (1-29) or simply CJC-1295 no-DAC. drops that linker entirely and clears the bloodstream in roughly half an hour.
Both molecules are synthetic analogs of growth hormone-releasing hormone (GHRH). Both bind the same receptor. Both are studied as growth-hormone secretagogues. But the half-life gap, measured in human research subjects by Teichman and colleagues in a 2006 Journal of Clinical Endocrinology & Metabolism paper (PMID: 16940447), is roughly 500-fold. That is not a rounding error. It is the entire reason researchers care which version they are studying.
This comparison reviews mechanism, half-life data, receptor pharmacology, and structural differences between the two. for laboratory research use only.
The two molecules share a backbone but diverge sharply on pharmacokinetics. The table below summarizes the headline differences researchers reference when designing experimental protocols.
| Property | CJC-1295 No-DAC (Modified GRF 1-29) | CJC-1295 With DAC |
|---|---|---|
| Structural class | GHRH analog (29-residue tetrasubstituted) | GHRH analog + albumin-binding linker |
| Reported half-life | ~30 minutes | 6–10 days |
| Receptor target | GHRH receptor (GHRHR) | GHRH receptor (GHRHR) |
| GH release pattern | Pulsatile, short duration | Sustained, days-long elevation |
| Albumin binding | No | Yes (covalent, via MPA linker) |
| First major human PK paper | Sackmann-Sala et al. (cited in CJC literature reviews) | Teichman et al., 2006 (PMID: 16940447) |
CJC-1295 started life as a research molecule designed by ConjuChem, a Canadian biotech, in the early 2000s. The team wanted a longer-lasting version of growth hormone-releasing hormone. the natural 44-residue compound that the hypothalamus uses to tell the pituitary to make growth hormone.
The first 29 amino acids of GHRH carry essentially all of its biological activity. That fragment, called GRF (1-29), was the obvious starting point. The problem: GRF (1-29) gets chewed up by an enzyme called dipeptidyl peptidase-4 (DPP-4) in seconds. By the time you’ve drawn blood, most of it is already cleaved.
ConjuChem’s chemists made four amino acid substitutions at positions 2, 8, 15, and 27 to block DPP-4 cleavage and prevent oxidation at vulnerable residues. That tetrasubstituted version is what the literature calls Modified GRF (1-29), or. confusingly. CJC-1295 without DAC. The half-life jumped from seconds to roughly 30 minutes. Useful, but still short.
To get from minutes to days, the team added a small chemical handle: maleimidopropionic acid (MPA), attached to the lysine at position 30. That handle has one job. When the compound enters the bloodstream, the MPA group reacts with a free cysteine residue on circulating serum albumin and forms a covalent bond. The compound is now permanently riding around on albumin, the most abundant protein in plasma.
The pharmacokinetic difference between the two molecules is not subtle. To understand why, it helps to think about how the body normally clears small compounds.
Compounds under about 5 kilodaltons get filtered out of the bloodstream by the kidneys with brutal efficiency. They also get cleaved by circulating proteases. Modified GRF (1-29) sits at roughly 3.4 kilodaltons. It survives DPP-4 thanks to the four substitutions, but it still gets filtered through the glomerulus and degraded by other peptidases. Hence the 30-minute half-life.
Serum albumin is a 66-kilodalton protein. It is too big to filter through the glomerulus under normal conditions, and it has a circulating half-life of about 19 days in humans. When CJC-1295 with DAC covalently bonds to albumin, the compound effectively inherits albumin’s clearance profile.
Teichman and colleagues (2006) measured this in healthy human research subjects across three escalating-dose cohorts and reported a terminal half-life of 5.8 to 8.1 days depending on dose, with sustained GH and IGF-1 elevation lasting six days or longer (PMID: 16940447).
“A single subcutaneous injection of CJC-1295 resulted in sustained, dose-dependent increases in mean plasma GH concentrations by 2- to 10-fold for 6 days or more.”
, Teichman et al. (2006), PMID: 16940447
This is the section researchers actually open the article for, so it earns a careful walkthrough.
The 30-minute figure for Modified GRF (1-29) comes from a combination of pharmacokinetic modeling and indirect measurement of GH pulse duration after subcutaneous administration. The compound is detectable in plasma briefly, triggers a sharp GH pulse from pituitary somatotrophs, and then clears. The result is a single, well-defined GH spike that mirrors the body’s natural pulsatile GHRH signaling.
The 6 to 10 day window comes directly from Teichman et al. (2006). The team ran a single-dose escalation study in 21 healthy adult research subjects, dosing at 60, 90, and 125 micrograms per kilogram of body weight, and measured plasma CJC-1295 concentrations along with GH and IGF-1 over time.
Half-life was 5.8 days at the lowest dose and crept up to 8.1 days at the highest dose. the modest dose-dependence reflects saturation kinetics of albumin binding sites at high concentrations.
Albumin has a finite number of free cysteine-34 residues available for MPA binding. At low CJC-1295-DAC doses, every compound molecule finds an albumin partner quickly. At very high doses, some compound circulates unbound and clears faster, which paradoxically would shorten apparent half-life. Teichman’s data showed the opposite. half-life increased slightly at higher doses. likely because of slower receptor-mediated clearance at saturating concentrations. The mechanism is still actively studied.
Both versions of CJC-1295 bind the same target: the GHRH receptor (GHRHR), a G-protein-coupled receptor expressed densely on pituitary somatotrophs.
When either molecule binds GHRHR, the receptor activates a Gs alpha subunit, which stimulates adenylyl cyclase, which raises intracellular cAMP, which activates protein kinase A (PKA). PKA phosphorylates transcription factors that drive growth hormone gene expression and trigger GH release from pre-formed secretory granules. This is the same cascade native GHRH uses, and the structural conservation of the (1-29) region is why the analogs work at all.
Here is where the half-life difference matters biologically. The pituitary evolved to respond to pulsatile GHRH signaling. short bursts followed by quiet periods. Pulsatile stimulation maintains receptor sensitivity. Continuous receptor activation, by contrast, can drive desensitization and downregulation through receptor internalization and altered gene expression.
No-DAC produces short, clean pulses. DAC produces sustained tonic stimulation. Sackmann-Sala and colleagues’ work on GHRH analog signaling, and earlier studies by Frohman and colleagues on GHRH pulse pharmacology, established the principle that pulsatile and sustained GHRH receptor activation produce measurably different downstream gene expression patterns in pituitary tissue (Frohman et al., 1990, PMID: 2105337). This is one reason researchers studying GH secretagogue biology generally do not treat the two CJC versions as interchangeable. they probe different signaling regimes.
⚠️ Common Misconception: The two CJC versions are sometimes described as the “short-acting” and “long-acting” variants of the same drug. Pharmacologically, they are not the same molecule and they do not produce equivalent biological effects. They share a backbone and a receptor target, but the signaling kinetics they generate differ enough that they answer different research questions.
⚗️ Research Disclaimer: All content on this page is intended exclusively for licensed researchers, academic institutions, and scientific professionals operating within approved laboratory settings. CJC-1295 (with and without DAC) is a research compound not approved for human clinical use by the FDA or equivalent regulatory authorities. This content does not constitute medical advice, clinical guidance, or a recommendation for use in humans or animals outside of approved research protocols.
The published literature on the two molecules has different shapes. DAC has a small but well-characterized human pharmacokinetic record. No-DAC has a more diffuse research footprint built largely on cellular and animal models of GHRH receptor pharmacology.
This is the foundational human PK study on CJC-1295 with DAC. Teichman’s team at ConjuChem dosed 21 healthy adults across three cohorts and tracked plasma compound, GH, and IGF-1 concentrations for 28 days. Mean GH concentrations rose 2 to 10 fold over baseline and stayed elevated for at least six days.
IGF-1. which integrates GH signaling over time. rose 1.5 to 3 fold and remained elevated for 9 to 11 days. No serious adverse events were reported in the single-dose study (PMID: 16940447).
Earlier work by Ionescu and Frohman (2006) characterized GH pulse responses to short-acting GHRH analogs and helped establish the pulsatile-stimulation framework that no-DAC fits into (PMID: 17047022). Their data showed that short-acting GHRH analogs produced GH pulses comparable in amplitude to native GHRH, but with the practical advantage of resistance to DPP-4 cleavage.
Raun and colleagues (1998), working on related GHRH analogs, showed that 4-substituted GRF (1-29) variants produced sustained 3 to 5 fold increases in baseline GH pulse amplitude in preclinical models, establishing the receptor-binding rationale that both modern CJC versions inherit (PMID: 9849822).
There is no published head-to-head human PK study directly comparing CJC-1295 with DAC against CJC-1295 without DAC under matched conditions. Researchers comparing the two rely on cross-study comparisons, which carry the usual caveats about study design, dosing schedules, and analytical methods. This is one of the open gaps in the GHRH-analog literature.
From a laboratory handling perspective, the two molecules behave similarly in lyophilized form but diverge once reconstituted.
Both versions are supplied as lyophilized compound powder. In this state, both are stable for extended periods at -20°C in sealed vials protected from light. Vitro Labs supplies CJC-1295 as part of the CJC-1295 + Ipamorelin blend (no-DAC version), with batch-specific COAs available for identity and purity verification.
Once reconstituted in bacteriostatic water, both compounds are subject to the standard degradation pathways for synthetic compounds. oxidation at methionine residues, deamidation at asparagine, and aggregation at higher concentrations. Stability profiles in solution are broadly similar across the two versions, since the MPA linker on DAC does not significantly alter aqueous-phase degradation chemistry.
Mass spectrometry distinguishes the two versions cleanly. CJC-1295 with DAC has a molecular mass roughly 197 Da higher than Modified GRF (1-29) due to the MPA group. HPLC retention times also differ. DAC elutes later under standard reversed-phase conditions because of the added hydrophobic linker. Researchers verifying batch identity should confirm both mass and retention against a reference standard.
Selection depends entirely on the experimental question being asked. The decision is not about which molecule is “better”. it is about which signaling regime the protocol requires.
Neither version of CJC-1295 is FDA-approved for any clinical indication. ConjuChem’s original development program for CJC-1295 was discontinued years ago after early-phase trials. Both versions are research compounds under FDA classification and are not approved for human consumption.
For sourcing, batch-specific Certificates of Analysis from independent laboratories are the practical baseline for confirming identity and purity. Vitro Labs ships every CJC-1295 + Ipamorelin batch with a COA from Freedom Diagnostics, an ISO-certified independent analytical laboratory. Identity is verified by HPLC and mass spectrometry; purity is reported per batch. Researchers can review the public COA library before adding to laboratory inventory.
⚠️ Research Disclaimer: This article is for educational and informational purposes only. All compounds discussed are research chemicals for laboratory use only and are not for human consumption.
CJC-1295 with DAC has a reported terminal half-life of 5.8 to 8.1 days in healthy human research subjects, measured by Teichman and colleagues in a 2006 single-dose escalation study (PMID: 16940447). CJC-1295 without DAC, also called Modified GRF (1-29), has a reported half-life of approximately 30 minutes. The roughly 500-fold difference comes from the DAC version’s covalent binding to serum albumin via a maleimidopropionic acid linker, which blocks renal filtration and slows enzymatic clearance.
Small compounds under about 5 kilodaltons are cleared rapidly by glomerular filtration in the kidneys and by circulating peptidases. The DAC modification adds a maleimidopropionic acid handle that forms a covalent bond with cysteine-34 on serum albumin, a 66-kilodalton plasma protein that is too large to filter under normal conditions. Once bound, the compound effectively inherits albumin’s circulation time, which in humans is roughly 19 days. The result is sustained GH and IGF-1 elevation lasting six days or longer (Teichman et al., 2006, PMID: 16940447).
Yes. Both versions are GHRH analogs based on the Modified GRF (1-29) backbone and bind the same target, the GHRH receptor (GHRHR), a G-protein-coupled receptor on pituitary somatotrophs. Receptor activation triggers the same downstream cAMP/PKA signaling cascade that native GHRH uses (Frohman et al., 1990, PMID: 2105337). The DAC linker does not change receptor binding affinity meaningfully. it only changes how long the compound remains in circulation.
Pharmacologically, no. Although both bind the same receptor, they produce fundamentally different signaling regimes. CJC-1295 without DAC generates short, pulsatile GH responses that mirror natural GHRH biology. CJC-1295 with DAC generates sustained, tonic receptor activation lasting days. Pulsatile and tonic GHRHR signaling drive different downstream gene-expression patterns in pituitary tissue, so the two versions are not substitutable in protocols that depend on signal duration or receptor desensitization dynamics.
Mass spectrometry distinguishes the two cleanly. CJC-1295 with DAC has a molecular mass roughly 197 daltons higher than Modified GRF (1-29) due to the maleimidopropionic acid group. HPLC retention times also differ. the DAC version elutes later under standard reversed-phase conditions because of the added hydrophobic linker. Researchers should confirm both mass and retention against a reference standard on a batch-specific Certificate of Analysis before use in laboratory protocols.
No published human pharmacokinetic study has directly compared CJC-1295 with DAC and CJC-1295 without DAC under matched dosing and analytical conditions. Researchers comparing the two molecules rely on cross-study inference from Teichman et al. (2006) for the DAC version (PMID: 16940447) and from earlier GHRH-analog work including Ionescu and Frohman (2006, PMID: 17047022) and Raun et al. (1998, PMID: 9849822) for the no-DAC version. This remains an open gap in the GHRH-analog literature.
⚗️ Research Disclaimer: All content on this page is intended exclusively for licensed researchers, academic institutions, and scientific professionals operating within approved laboratory settings. CJC-1295 (with and without DAC) is a research compound not approved for human clinical use by the FDA or equivalent regulatory authorities. This content does not constitute medical advice, clinical guidance, or a recommendation for use in humans or animals outside of approved research protocols.
