CJC-1295 is a synthetic growth hormone-releasing hormone (GHRH) analog developed to stimulate endogenous growth hormone secretion via the hypothalamic-pituitary axis. Researchers encounter two forms of CJC-1295: one with Drug Affinity Complex (DAC) and one without. While both share the same core peptide sequence and mechanism of action, the presence or absence of the DAC moiety creates pharmacokinetic differences with significant implications for experimental design. This guide provides a detailed, evidence-based comparison to help Canadian researchers select the appropriate variant for their studies.
All information in this guide is provided for research purposes only. CJC-1295 (with and without DAC) is not approved for human consumption or therapeutic use.
Background: What Is CJC-1295?
CJC-1295 (tetrasubstituted GHRH 1-29) was originally developed by ConjuChem Biotechnologies as a long-acting GHRH analog. The base peptide is a modified form of the endogenous 1-29 fragment of growth hormone-releasing hormone, with four amino acid substitutions (D-Ala², Glu³, Ala¹⁵, Leu²⁷) that provide resistance to enzymatic degradation by dipeptidyl peptidase-IV (DPP-IV).
The result is a GHRH analog with approximately 10-fold greater stability than native GHRH, enabling sustained stimulation of growth hormone secretion from anterior pituitary somatotrophs. For comprehensive background on CJC-1295’s pharmacology, see our CJC-1295 complete guide for Canadian researchers.
What Is DAC (Drug Affinity Complex)?
The Drug Affinity Complex is a C-terminal modification consisting of a lysine residue linked to a reactive maleimidopropanoyl group. This chemical moiety enables covalent binding of CJC-1295 to serum albumin (via cysteine-34) through a thioether bond.
Pharmacokinetic Impact of DAC
The albumin-binding property of DAC fundamentally alters CJC-1295’s pharmacokinetics:
- Half-life: CJC-1295 with DAC has an estimated half-life of 5.8–8.1 days in humans (clinical trial data), compared to approximately 30 minutes for the non-DAC variant (Modified GRF 1-29)
- Protein binding: >90% of circulating CJC-1295 with DAC is albumin-bound, creating a slow-release reservoir
- Bioavailability: Sustained therapeutic concentrations are maintained over days rather than hours
- Accumulation potential: With weekly or biweekly dosing, CJC-1295 with DAC can accumulate, producing progressively increasing GH and IGF-1 levels
CJC-1295 Without DAC (Modified GRF 1-29)
CJC-1295 without DAC is technically the same core peptide (tetrasubstituted GHRH 1-29) but lacks the albumin-binding lysine-maleimidopropanoyl group. This variant — sometimes labeled “Modified GRF 1-29” or “CJC-1295 No DAC” — has a much shorter half-life of approximately 30 minutes, reflecting its lack of albumin anchoring.
The shorter half-life means that the GH-releasing pulse from CJC-1295 No DAC mimics the natural pulsatile pattern of endogenous GHRH more closely than the DAC variant. This pharmacokinetic distinction has important implications for research design.
Pharmacokinetic Comparison
| Parameter | CJC-1295 with DAC | CJC-1295 No DAC |
|—|—|—|
| Half-life | ~5.8–8.1 days | ~30 minutes |
| Protein binding | Albumin-bound (>90%) | Minimal |
| GH release pattern | Sustained/elevated baseline | Pulsatile |
| IGF-1 trajectory | Gradually rising, sustained | Transient peaks |
| Dosing frequency | 1–2× per week | 1–3× per day |
| Accumulation risk | Yes, with repeated dosing | Negligible |
| Peak GH response | Lower peak, longer duration | Higher peak, shorter duration |
Implications for Research Design
The choice between CJC-1295 with DAC and No DAC fundamentally shapes experimental outcomes:
- CJC-1295 with DAC produces a sustained elevation of GH and IGF-1, creating a relatively steady-state hormonal environment. This is useful for studies modeling chronic GH sufficiency or evaluating long-term anabolic/metabolic effects.
- CJC-1295 No DAC produces discrete, pulsatile GH spikes that more closely replicate physiological GHRH signaling. This is preferable for studies investigating natural GH pulsatility, circadian rhythm, or the effects of patterned versus continuous GH exposure.
IGF-1 Response Comparison
CJC-1295 with DAC: IGF-1 Trajectory
Clinical data from ConjuChem’s Phase I and II trials demonstrate that CJC-1295 with DAC produces a dose-dependent increase in serum IGF-1 that:
- Rises over 3–5 days post-injection
- Reaches a plateau by day 7–10
- Sustains elevated levels for 10–14 days after a single dose
- Shows accumulation with repeated weekly dosing, reaching 2–3× baseline IGF-1 levels
The sustained IGF-1 elevation reflects the continuous albumin-bound reservoir gradually releasing active peptide and maintaining GH axis stimulation.
CJC-1295 No DAC: IGF-1 Trajectory
With the shorter half-life, CJC-1295 No DAC produces:
- Rapid IGF-1 peaks within 2–4 hours of administration
- Return toward baseline within 6–12 hours
- No cumulative effect with repeated dosing at appropriate intervals
- IGF-1 levels that track more closely with each dosing event
This transient IGF-1 profile is advantageous for researchers studying pulsatile GH axis regulation or attempting to avoid sustained IGF-1 elevation.
For researchers interested in the broader GH/IGF-1 axis, our HGH peptides guide covers the full spectrum of growth hormone–modulating compounds.
Research Protocols
CJC-1295 with DAC
Reconstitution:
1. Allow vial to reach room temperature
2. Reconstitute with bacteriostatic water (typically 2 mL per vial)
3. Gentle swirl — do not vortex
4. Store at 2–8°C; use within 14–21 days
Research dosing (animal models):
- Chronic GH axis studies: 1–2 mg/kg subcutaneously, once weekly
- IGF-1 dose-response: 0.5–5 mg/kg, single dose with serial IGF-1 sampling over 14 days
- Long-term metabolic studies: 0.5–1 mg/kg/week over 8–12 weeks
Note on accumulation: Due to the long half-life, researchers must account for drug accumulation in study design. Steady-state levels may take 4–5 weeks to achieve with weekly dosing.
CJC-1295 No DAC (Modified GRF 1-29)
Reconstitution:
1. Same procedure as above
2. Store reconstituted solution at 2–8°C; use within 7–14 days (shorter recommended window due to the absence of albumin-binding stabilization)
Research dosing (animal models):
- Pulsatile GH studies: 5–20 μg/kg subcutaneously, 1–3× daily
- GHRH axis studies: 10–50 μg/kg, administered at physiological GHRH pulse intervals
- Combination protocols with GHRP: 5–20 μg/kg CJC-1295 No DAC combined with a GHRP (e.g., ipamorelin) at 5–20 μg/kg
Use our peptide calculator to compute precise concentrations, injection volumes, and dosing schedules for your experimental design.
Combination with GHRPs
Both CJC-1295 variants are frequently combined with growth hormone secretagogue receptor (GHS-R) agonists (e.g., ipamorelin, GHRP-2, GHRP-6) in research protocols. The synergistic mechanism — GHRH (CJC-1295) and GHRP acting on distinct receptor populations to amplify the GH pulse — is well-documented:
- CJC-1295 with DAC + GHRP: Produces sustained GH elevation with amplified periodic pulses. Useful for modeling chronic GH axis activation.
- CJC-1295 No DAC + GHRP: Produces discrete, high-amplitude GH pulses mimicking physiological pulsatility. Useful for studies of natural GH rhythm.
For detailed GHRP protocols, see our ipamorelin research guide.
Selecting the Right Variant for Your Research
Choose CJC-1295 with DAC When:
- Studying chronic, steady-state GH axis elevation
- Modeling conditions of sustained GH sufficiency
- Evaluating long-term IGF-1–mediated effects (bone density, protein synthesis, etc.)
- Convenience of less frequent dosing is a practical necessity
- Investigating the pharmacokinetic properties of albumin-bound peptides
Choose CJC-1295 No DAC When:
- Studying physiological, pulsatile GH secretion patterns
- Investigating GH rhythm, circadian variation, or pulse frequency effects
- Minimizing IGF-1 accumulation is experimentally important
- Combining with GHRPs for acute GH pulse amplification
- Modeling the pharmacology of short-acting GHRH analogs
Practical Considerations
- Cost efficiency: CJC-1295 with DAC requires less frequent dosing, which may reduce total peptide consumption over long study durations
- Control precision: CJC-1295 No DAC offers finer temporal control, enabling researchers to define precise “on” and “off” periods in the GH axis
- Regulatory documentation: Both variants are research-grade compounds and require identical research-use documentation
Safety and Regulatory Considerations
Research-Only Status
Both CJC-1295 with DAC and CJC-1295 No DAC are classified as research peptides. Neither is approved by Health Canada, the FDA, or any regulatory authority for human use. All CJC-1295 products from Webber Science are labeled for research purposes only and are not for human consumption.
Preclinical and Clinical Safety Data
CJC-1295 with DAC has the more extensive safety database, having progressed through Phase II clinical trials:
- Generally well tolerated at doses up to 100 μg/kg in healthy volunteers
- Primary adverse effects: transient injection site reactions, mild headache, flushing
- IGF-1 elevations were dose-dependent and reversible
- No serious adverse events attributed to the peptide
CJC-1295 No DAC has a smaller published safety database, primarily consisting of preclinical and anecdotal research reports. Its shorter half-life inherently limits the duration and magnitude of hormonal exposure, which may offer a more favorable safety profile for certain experimental designs — though this has not been formally demonstrated in clinical trials.
Canadian Regulatory Notes
CJC-1295 (both variants) is not scheduled under Canada’s Controlled Drugs and Substances Act. Researchers must comply with Health Canada regulations governing investigational compounds and maintain appropriate research-use documentation. Institutional research ethics board (REB) approval may be required for in vivo studies.
Frequently Asked Questions
What is the main difference between CJC-1295 with DAC and without DAC?
The DAC (Drug Affinity Complex) is a chemical modification that binds CJC-1295 to serum albumin, extending its half-life from approximately 30 minutes (No DAC) to approximately 6–8 days (with DAC). This changes the GH release pattern from pulsatile to sustained and reduces dosing frequency from daily to weekly.
Can CJC-1295 with DAC and No DAC be used interchangeably?
No. Their pharmacokinetic profiles are fundamentally different and are not interchangeable. CJC-1295 with DAC produces sustained, accumulating GH/IGF-1 elevation, while No DAC produces discrete, pulsatile GH spikes. The choice depends entirely on the experimental question being asked.
Does CJC-1295 with DAC cause IGF-1 accumulation?
Yes. Due to its long half-life and albumin binding, CJC-1295 with DAC can produce progressively increasing IGF-1 levels with repeated dosing. This accumulation reaches a plateau after approximately 4–5 weeks of weekly administration. Researchers should account for this in study design, particularly when IGF-1 levels are an outcome measure.
Why is CJC-1295 No DAC sometimes called “Modified GRF 1-29”?
Both names refer to the same compound: the tetrasubstituted GHRH 1-29 peptide without the DAC modification. The “Modified GRF 1-29” nomenclature is more precise, as “CJC-1295” technically refers to the DAC-containing variant from ConjuChem’s drug development program. However, market convention has adopted “CJC-1295 No DAC” as the common label for this peptide.
Where can Canadian researchers purchase CJC-1295?
Both variants are available from Webber Science for qualified research laboratories:
Summary
CJC-1295 with DAC and CJC-1295 No DAC share the same core pharmacological mechanism — GHRH receptor agonism leading to endogenous GH secretion — but differ fundamentally in pharmacokinetic profile. The DAC variant provides sustained, albumin-bound exposure suitable for chronic GH axis studies, while the No DAC variant delivers pulsatile, short-acting stimulation appropriate for physiological rhythm research.
Key takeaways:
- CJC-1295 with DAC: ~6–8 day half-life, sustained GH/IGF-1 elevation, weekly dosing, accumulation potential
- CJC-1295 No DAC: ~30 minute half-life, pulsatile GH release, daily dosing, no accumulation
- The variant choice should be driven by experimental objectives, not convenience alone
- Both are available from Webber Science as research peptides — for research purposes only
All products are sold for research purposes only. Not for human consumption or therapeutic use.
For deeper context on GH-modulating peptides, explore our HGH peptides guide, the CJC-1295 complete guide for Canadian researchers, and ipamorelin research guide for GHRP combination protocols. Use the peptide calculator for precise dosing calculations.