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CJC-1295 with DAC vs Without DAC: Key Differences Explained

Compare CJC-1295 with DAC and CJC-1295 without DAC (Mod GRF 1-29). Learn the key differences in half-life, dosing, growth hormone release patterns, and which variant researchers prefer for different study goals.

February 5, 2026
12 min read
CJC-1295 with DAC vs Without DAC: Key Differences Explained

CJC-1295 is one of the most widely studied growth hormone-releasing hormone (GHRH) analogs in peptide research. But if you've spent any time looking into it, you've likely encountered a confusing fork in the road: CJC-1295 with DAC and CJC-1295 without DAC. Despite sharing a name, these two peptides behave quite differently in the body—and understanding those differences matters for anyone evaluating growth hormone secretagogue research.

This guide breaks down the science behind both variants, their pharmacokinetics, their effects on growth hormone release, and the practical considerations that distinguish them in research settings.

🔑 Key Takeaways

  • CJC-1295 with DAC has a dramatically longer half-life (~6-8 days) compared to without DAC (~30 minutes)
  • The "without DAC" variant (Mod GRF 1-29) produces pulsatile GH release that more closely mimics natural secretion
  • CJC-1295 with DAC creates sustained, elevated baseline GH—a fundamentally different release pattern
  • Most current research protocols pair CJC-1295 without DAC with a GHRP like ipamorelin for synergistic pulsatile release
  • Neither variant is approved for clinical use; all findings come from preclinical and early-phase human research
Understanding the Basics

What Is CJC-1295?

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), the natural signal peptide produced by the hypothalamus that tells the pituitary gland to release growth hormone. The native GHRH molecule is a 44-amino acid peptide with an extremely short half-life of just 5-7 minutes in the bloodstream—enzymes called dipeptidyl peptidases rapidly degrade it.

Researchers at ConjuChem Biotechnologies developed CJC-1295 to overcome this limitation. The core peptide is a modified 29-amino acid fragment of GHRH (amino acids 1-29, sometimes called "tetrasubstituted GRF 1-29") with four amino acid substitutions at positions 2, 8, 15, and 27 to resist enzymatic degradation. This base peptide significantly extends the functional half-life compared to native GHRH.

But the real divergence comes from what happens next: whether or not a Drug Affinity Complex (DAC) is attached to this modified peptide.

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What Is DAC (Drug Affinity Complex)?

DAC is a chemical modification technology developed by ConjuChem. It attaches a reactive chemical group (maleimidopropionic acid linked to a lysine linker) to the peptide, which then forms a covalent bond with serum albumin—the most abundant protein in blood plasma—after injection.

ℹ️ How DAC Works: Once injected, the DAC-modified peptide binds to albumin in the bloodstream. Since albumin has a half-life of approximately 19-21 days, the peptide effectively "hitchhikes" on this long-lived carrier protein, dramatically extending its own functional duration from minutes to days.

This albumin-binding technology is the entire basis for the difference between the two variants. The peptide's core biological activity—stimulating the GHRH receptor on pituitary somatotroph cells—remains the same. What changes is how long and in what pattern that stimulation occurs.

Side-by-Side Comparison

CJC-1295 with DAC vs Without DAC: Head-to-Head

Property CJC-1295 with DAC CJC-1295 without DAC (Mod GRF 1-29)
Other Names CJC-1295 DAC, DAC:GRF Mod GRF 1-29, CJC-1295 no DAC, Modified GRF (1-29)
Half-Life ~6-8 days ~30 minutes
GH Release Pattern Sustained elevation (steady-state baseline increase) Pulsatile (acute spikes that return to baseline)
Molecular Weight ~3,647 Da (with DAC linker) ~3,367 Da
Dosing Frequency (Research) Once or twice weekly 1-3 times daily
Albumin Binding Yes (covalent) No
IGF-1 Elevation Sustained increase over days Transient increase following each dose
Mimics Natural GH Pattern No — creates constant stimulation Yes — preserves pulsatile rhythm
Commonly Stacked With Typically used alone Ipamorelin, GHRP-2, or GHRP-6
Clinical Trial Data Phase I/II completed (ConjuChem) Limited formal trials; extensive preclinical data
Deep Dive: The DAC Variant

CJC-1295 with DAC: Extended-Release GH Stimulation

Pharmacokinetics

The defining characteristic of CJC-1295 with DAC is its remarkable persistence in the bloodstream. After a single subcutaneous injection, the peptide's albumin-binding mechanism extends its functional half-life to approximately 6-8 days. This means a single dose can maintain elevated GH-releasing activity for over a week.

In clinical studies conducted by ConjuChem, a single 60 ÎĽg/kg dose of CJC-1295 with DAC produced a 2-10 fold increase in GH levels that persisted for up to 6 days. IGF-1 levels (a downstream marker of GH activity) remained elevated for 9-11 days following a single injection. After multiple weekly doses, IGF-1 levels increased by 1.5-3 fold above baseline.

GH Release Pattern

This is where the critical distinction lies. CJC-1295 with DAC does not produce the sharp, pulsatile bursts of growth hormone that characterize natural GH secretion. Instead, it creates a sustained elevation—a "raised floor" of GH activity that persists between doses.

⚠️ Important Consideration: Natural growth hormone secretion follows a pulsatile pattern, with the largest pulse occurring during deep sleep. Continuous GH elevation, as produced by CJC-1295 with DAC, represents a fundamentally different hormonal pattern. The long-term implications of sustained (non-pulsatile) GH elevation versus natural pulsatile release are not fully understood.

Potential Advantages

  • Dosing convenience: Once or twice weekly injections versus multiple daily doses
  • Consistent IGF-1 elevation: No peaks and troughs between doses
  • Simplicity: Fewer variables to manage in research protocols
  • Proven human data: Phase I/II clinical trials demonstrated safety and efficacy for GH/IGF-1 elevation

Potential Concerns

  • Non-physiological GH pattern: Sustained stimulation may lead to receptor desensitization over time
  • Cortisol and prolactin elevation: Some research reports increased cortisol and prolactin as side effects of sustained GHRH stimulation
  • Difficulty adjusting dose: Once injected, the long half-life means effects cannot be quickly reversed
  • GH bleed: The constant presence may blunt the body's natural GH pulses rather than enhance them
Deep Dive: The No-DAC Variant

CJC-1295 Without DAC (Mod GRF 1-29): Pulsatile GH Release

Pharmacokinetics

CJC-1295 without DAC—more accurately called Modified GRF (1-29) or Mod GRF 1-29—retains the four amino acid substitutions that protect it from rapid enzymatic degradation but lacks the albumin-binding DAC component. The result is a peptide with a half-life of approximately 30 minutes, significantly longer than native GHRH's 5-7 minutes but far shorter than the DAC variant's multi-day persistence.

This shorter half-life is actually considered a feature, not a bug, by many researchers. It means each injection produces a discrete pulse of GHRH receptor stimulation that rises, peaks, and clears—mimicking the natural pulsatile pattern of hypothalamic GHRH release.

GH Release Pattern

When injected, Mod GRF 1-29 triggers a sharp increase in GH secretion from the pituitary within 15-30 minutes, peaking at approximately 30-60 minutes, and returning to baseline within 2-3 hours. This acute, spike-and-return pattern closely resembles the body's own GH pulses.

âś“ Physiological Advantage: By preserving pulsatile GH release, Mod GRF 1-29 works with the body's natural rhythm rather than overriding it. Research suggests pulsatile GH stimulation is less likely to cause receptor desensitization and may be more effective for tissue-level responses compared to continuous exposure.

The Synergy with GHRPs

One of the most significant practical aspects of Mod GRF 1-29 is its synergy with growth hormone-releasing peptides (GHRPs) like ipamorelin, GHRP-2, and GHRP-6. While GHRH analogs stimulate GH release via the GHRH receptor, GHRPs work through the separate ghrelin/GHS receptor. When combined, these two pathways produce a synergistic effect—the GH pulse from the combination is substantially larger than the sum of either peptide alone.

The most commonly researched pairing is CJC-1295 without DAC + Ipamorelin. This combination has become the standard protocol in growth hormone secretagogue research because ipamorelin is considered the most selective GHRP, stimulating GH release without significantly affecting cortisol or prolactin levels.

Pro Tip

In research contexts, the CJC-1295 (no DAC) + Ipamorelin combination is sometimes referred to as a "GH pulse stack." The Mod GRF 1-29 amplifies the GH-releasing signal while ipamorelin initiates it through a complementary pathway. Research suggests this combination can produce GH pulses 3-5x greater than either peptide alone. Read our full CJC-1295 and Ipamorelin synergy analysis for details.

Potential Advantages

  • Mimics natural physiology: Pulsatile release preserves the body's GH rhythm
  • Lower desensitization risk: Receptor recovery between pulses maintains sensitivity
  • Synergy with GHRPs: Can be stacked with ipamorelin or GHRP-2 for amplified effects
  • Dose flexibility: Short half-life allows rapid adjustment of research protocols
  • Fewer hormonal side effects: Less likely to elevate cortisol or prolactin compared to continuous stimulation

Potential Concerns

  • Multiple daily doses: Requires 1-3 injections per day for sustained effect
  • Timing sensitivity: Best administered at specific times (fasting, pre-sleep) for optimal GH response
  • More complex protocols: Often requires stacking with a GHRP for full effect
The Science of GH Release Patterns

Why GH Release Pattern Matters

The debate between these two CJC-1295 variants ultimately comes down to a fundamental question in endocrinology: is pulsatile or continuous growth hormone stimulation more beneficial?

The Case for Pulsatile Release

Natural GH secretion is pulsatile by design. The hypothalamus alternates between GHRH release (stimulating GH) and somatostatin release (suppressing GH), creating rhythmic bursts throughout the day. The largest pulse occurs during Stage 3 deep sleep, with smaller pulses following exercise, fasting, and other physiological triggers.

Research suggests this pulsatile pattern is not arbitrary—it serves important biological functions:

  • Receptor sensitivity: GH receptors in target tissues appear to respond more robustly to intermittent stimulation. Continuous exposure can lead to downregulation.
  • Differential gene expression: Studies in animal models show that pulsatile versus continuous GH exposure activates different patterns of gene expression in the liver, with pulsatile patterns associated with sex-specific IGF-1 production and metabolic regulation.
  • Lipolysis: GH-mediated fat breakdown appears to be more effectively stimulated by pulsatile release patterns.
  • Feedback preservation: Pulsatile stimulation preserves the somatostatin feedback loop, preventing chronic suppression of the GH axis.

The Case for Sustained Release

However, sustained GH elevation is not without precedent or theoretical merit:

  • IGF-1 consistency: Sustained GH stimulation produces more consistent IGF-1 levels, which may be relevant for anabolic and tissue-repair processes.
  • Practical simplicity: For research subjects, weekly dosing represents significantly less burden than multiple daily injections.
  • Clinical data: The Phase I/II trials of CJC-1295 with DAC demonstrated meaningful, dose-dependent IGF-1 elevation with acceptable safety profiles in the study timeframes.
đź“ť Note: The distinction between pulsatile and sustained GH release patterns is analogous to the difference between natural testosterone production (pulsatile, with diurnal variation) and testosterone replacement therapy (which aims for more consistent levels). Both approaches have trade-offs, and the optimal strategy may depend on the specific research goals.
Research Protocols

Typical Research Protocols

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CJC-1295 with DAC Protocols

Protocol Dosage Frequency Duration
Conservative 1-2 mg Once weekly 8-12 weeks
Standard 2 mg Twice weekly 8-12 weeks
ℹ️ Info: Due to the long half-life, CJC-1295 with DAC reaches steady-state plasma levels after approximately 2-3 weeks of consistent dosing. Researchers should account for this accumulation period when designing study timelines.

CJC-1295 Without DAC (Mod GRF 1-29) Protocols

Protocol Dosage Frequency Duration
Solo (basic) 100 mcg 1-3 times daily 8-12 weeks
With Ipamorelin 100 mcg Mod GRF + 100 mcg Ipamorelin 2-3 times daily 8-12 weeks
Pre-sleep only 100-200 mcg (± GHRP) Once daily (before bed) Ongoing

Pro Tip

GH release from GHRH analogs is blunted by elevated blood sugar and free fatty acids. Research protocols with Mod GRF 1-29 typically specify administration on an empty stomach—ideally 2+ hours after the last meal—to maximize the GH response. The pre-sleep dose is popular because it coincides with the body's natural nocturnal GH surge and a fasting window. See our guide on peptides and food timing for details.

Clinical Evidence

What Does the Research Show?

CJC-1295 with DAC Clinical Trials

The most robust human data comes from ConjuChem's clinical development program. A Phase I/II trial published in the Journal of Clinical Endocrinology & Metabolism (2006) studied CJC-1295 with DAC in healthy adults aged 21-61:

  • Single doses of 30, 60, or 125 ÎĽg/kg produced dose-dependent increases in GH and IGF-1
  • Mean GH levels increased 2-10 fold for up to 6 days after a single injection
  • IGF-1 levels increased 1.5-3 fold and remained elevated for 9-11 days
  • After 2-3 weekly doses, steady-state IGF-1 elevation was achieved
  • The most common adverse events were injection site reactions, headache, and diarrhea
  • No serious adverse events were reported in the study timeframe
⚠️ Important Context: ConjuChem's clinical development program for CJC-1295 with DAC was discontinued after a subject death in a subsequent trial. While the death was determined to be due to a pre-existing cardiac condition, the program was not resumed. This means long-term safety data from controlled trials does not exist for this compound.

Mod GRF 1-29 Research

Direct clinical trial data for Mod GRF 1-29 specifically is more limited, though the broader class of GHRH analogs (including the parent compound sermorelin, which is FDA-approved for GH deficiency diagnosis) is well-studied. The key findings from available research include:

  • Acute GH release of 3-10x baseline within 30-60 minutes of administration
  • Synergistic GH release when combined with GHRPs (3-5x greater than either alone)
  • Preservation of pulsatile GH patterns and somatostatin feedback
  • Comparable IGF-1 elevation to the DAC variant when dosed appropriately over time
  • Good tolerability with minimal cortisol or prolactin elevation

Much of the supporting evidence comes from research on sermorelin (the unmodified GRF 1-29) and tesamorelin (another modified GHRH analog FDA-approved for HIV-associated lipodystrophy), which share the same mechanism of action.

Choosing Between Variants

Which Variant Is Right for Your Research?

🔬

Choose CJC-1295 with DAC When

Research goals prioritize simplicity, consistent IGF-1 elevation, and minimal dosing frequency. Suited for protocols studying sustained GH axis stimulation.

⚡

Choose Mod GRF 1-29 (No DAC) When

Research goals prioritize physiological GH pulsatility, GHRP stacking protocols, and dose flexibility. Preferred for protocols studying natural GH augmentation.

đź’ˇ

The Research Consensus

The majority of current GH secretagogue research uses CJC-1295 without DAC paired with ipamorelin, favoring pulsatile release patterns.

Decision Factors

When evaluating which CJC-1295 variant to use in a research context, consider the following:

1

Research Duration and Complexity

Longer studies with simpler protocols may favor the DAC variant's weekly dosing. Short-term studies or those examining acute GH responses benefit from the no-DAC variant's rapid onset and clearance.

2

GH Pattern Goals

If the study aims to augment natural GH physiology, the pulsatile release of Mod GRF 1-29 is preferred. If consistent, elevated GH/IGF-1 is the primary endpoint, the DAC variant may be more appropriate.

3

Stacking Considerations

Planning to combine with ipamorelin or another GHRP? The no-DAC variant is the standard choice, as both peptides are administered simultaneously for synergistic pulsatile release. The DAC variant is typically used as a standalone. See our peptide stacking guide for more details.

4

Side Effect Profile

CJC-1295 with DAC's sustained stimulation has been associated with cortisol and prolactin elevation in some subjects. The no-DAC variant, especially paired with ipamorelin, generally shows a cleaner hormonal side effect profile in available research.

Safety & Side Effects

Safety Considerations for Both Variants

Both CJC-1295 variants share some common side effects related to GH stimulation, but the duration and intensity differ based on the half-life characteristics:

Common Effects (Both Variants)

  • Injection site reactions: Redness, swelling, or discomfort at the injection site (generally mild and transient)
  • Water retention: GH elevation can cause fluid retention, particularly in the first weeks. See our article on peptide water retention for management strategies.
  • Tingling or numbness: Paresthesias in hands or feet, related to GH-mediated nerve effects
  • Headache: Reported in clinical trials, generally mild
  • Increased hunger: More common with the no-DAC variant when paired with GHRPs like GHRP-6

DAC-Specific Considerations

  • Cortisol elevation: Sustained GHRH stimulation can increase cortisol production—a significant concern for chronic use
  • Prolactin elevation: Some research subjects show elevated prolactin, which can affect reproductive hormone balance
  • Irreversibility: Once injected, the multi-day half-life means side effects cannot be rapidly managed by discontinuation

No-DAC-Specific Considerations

  • Timing sensitivity: Effects are blunted by food intake, requiring fasting protocols
  • Injection frequency burden: 2-3 daily injections may increase injection site discomfort over time
  • GHRP-dependent side effects: When stacked with GHRP-2 or GHRP-6, additional effects like intense hunger and cortisol elevation can occur (though ipamorelin largely avoids these)
Frequently Asked Questions

Frequently Asked Questions

Can I switch from CJC-1295 with DAC to the without-DAC variant mid-protocol?
Technically yes, but researchers should account for the DAC variant's long half-life. After the last DAC injection, residual activity persists for 1-2 weeks. Starting the no-DAC variant during this washout period means overlapping stimulation. Most research protocols recommend waiting at least 2 weeks after the last DAC dose before transitioning to Mod GRF 1-29 to establish a clean baseline.
Is CJC-1295 without DAC the same as sermorelin?
No. Both are GHRH analogs based on the GRF 1-29 fragment, but Mod GRF 1-29 has four amino acid substitutions (at positions 2, 8, 15, and 27) that sermorelin lacks. These substitutions make Mod GRF 1-29 more resistant to enzymatic degradation, extending its functional half-life from ~10 minutes (sermorelin) to ~30 minutes. Despite this difference, both produce similar pulsatile GH release patterns. Our ipamorelin vs sermorelin comparison covers related distinctions.
Can CJC-1295 with DAC be combined with ipamorelin?
While technically possible, this combination is less common in research. The DAC variant provides continuous GHRH receptor stimulation, so adding pulsatile GHRP stimulation creates a mixed pattern—neither purely pulsatile nor purely sustained. Most researchers who want the CJC-1295 + Ipamorelin synergy use the no-DAC variant specifically because both components clear quickly, producing clean, discrete GH pulses.
Which CJC-1295 variant produces more GH overall?
This depends on the timeframe. CJC-1295 with DAC produces a higher area-under-the-curve (AUC) of GH exposure from a single injection due to its sustained release. However, multiple daily doses of the no-DAC variant (especially when stacked with a GHRP) can produce comparable or higher total daily GH output, with the advantage of higher peak concentrations during each pulse. The clinical significance of peak GH levels versus total GH exposure is still debated in endocrinology research.
Does CJC-1295 suppress natural GH production?
This is an important distinction between GHRH analogs and exogenous GH. CJC-1295 (both variants) works by stimulating the pituitary to produce and release its own growth hormone—it doesn't supply external GH. In principle, this means the pituitary's GH-producing capacity is maintained. However, the DAC variant's continuous stimulation raises concerns about potential desensitization of GHRH receptors over extended periods, which could temporarily blunt natural GH pulsatility. The no-DAC variant's intermittent stimulation is considered less likely to cause this effect.
What's the best time of day to administer CJC-1295 without DAC?
Research protocols commonly specify three optimal timing windows: (1) upon waking in a fasted state, (2) post-exercise, and (3) before bed. The pre-sleep dose is considered particularly important as it amplifies the body's natural nocturnal GH surge. Food—especially carbohydrates and fats—blunts GH release, so a fasting window of at least 2 hours before and 30-60 minutes after administration is typically maintained. Check our optimal peptide timing guide for comprehensive scheduling advice.
How do I know if my CJC-1295 contains DAC or not?
This is a common source of confusion. Reputable suppliers clearly label whether their product contains DAC. Key identifiers: if the product is labeled simply "CJC-1295" without further specification, it may be either variant. Look for explicit labels like "CJC-1295 DAC," "CJC-1295 with DAC," "Mod GRF 1-29," or "CJC-1295 no DAC." The molecular weight differs (~3,647 Da with DAC vs ~3,367 Da without), which can be verified via certificates of analysis. Our peptide purity guide covers how to read COAs.
Related Reading

Further Research

Understanding CJC-1295 variants is just one piece of the growth hormone secretagogue puzzle. For a more complete picture, explore these related resources:

  • CJC-1295 vs Ipamorelin: Complete Comparison — How these two peptide classes work together
  • CJC-1295 and Ipamorelin Synergy Research — Deep dive into the synergistic mechanisms
  • Growth Hormone Secretagogues Overview — The full landscape of GH-releasing compounds
  • GHRP-2 vs GHRP-6 Comparison — Choosing the right GHRP to stack with Mod GRF 1-29
  • MK-677 vs Injectable Peptides — Oral GH secretagogue vs injectable options
  • Peptides vs HGH — How secretagogues compare to exogenous growth hormone
  • How to Reconstitute Peptides — Essential preparation guide for both variants
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. CJC-1295, both with and without DAC, is a research compound that has not been approved by the FDA or any regulatory agency for human therapeutic use. All information is derived from preclinical research and early-phase clinical studies. Always consult a qualified healthcare provider before starting any new supplement, medication, or treatment. Individual results may vary.

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Related Topics

CJC-1295DACMod GRF 1-29growth hormoneGHRHpeptide comparisonipamorelinGH secretagoguespulsatile releaseIGF-1

Table of Contents31 sections

What Is CJC-1295?What Is DAC (Drug Affinity Complex)?CJC-1295 with DAC vs Without DAC: Head-to-HeadCJC-1295 with DAC: Extended-Release GH StimulationPharmacokineticsGH Release PatternPotential AdvantagesPotential ConcernsCJC-1295 Without DAC (Mod GRF 1-29): Pulsatile GH ReleasePharmacokineticsGH Release PatternThe Synergy with GHRPsPotential AdvantagesPotential ConcernsWhy GH Release Pattern MattersThe Case for Pulsatile ReleaseThe Case for Sustained ReleaseTypical Research ProtocolsCJC-1295 with DAC ProtocolsCJC-1295 Without DAC (Mod GRF 1-29) ProtocolsWhat Does the Research Show?CJC-1295 with DAC Clinical TrialsMod GRF 1-29 ResearchWhich Variant Is Right for Your Research?Decision FactorsSafety Considerations for Both VariantsCommon Effects (Both Variants)DAC-Specific ConsiderationsNo-DAC-Specific ConsiderationsFrequently Asked QuestionsFurther Research

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