CJC-1295 with DAC

Overview

CJC-1295 with DAC is a synthetic analog of growth hormone-releasing hormone (GHRH) that incorporates a Drug Affinity Complex (DAC) — a reactive chemical moiety that covalently binds to serum albumin after injection. This albumin conjugation dramatically extends the peptide's half-life from approximately 30 minutes (for the unconjugated form) to 6-8 days, enabling sustained elevation of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) from a single administration.

Developed by ConjuChem Biotechnologies (now ConjuChem LLC), CJC-1295 DAC underwent Phase II clinical trials that demonstrated its ability to maintain elevated GH and IGF-1 levels for extended periods. The compound represents a fundamentally different pharmacological approach from short-acting GH secretagogues — rather than producing discrete GH pulses, it generates a sustained elevation of the GH/IGF-1 axis.

Structure and Properties

The Base Peptide: Modified GRF (1-29)

CJC-1295 DAC is built on a modified version of the first 29 amino acids of native GHRH (also known as GRF 1-29 or sermorelin). Four amino acid substitutions improve metabolic stability:

• Position 2: Alanine replaced with D-Alanine — resists DPP-IV cleavage
• Position 8: Asparagine replaced with Glutamine — prevents asparagine deamidation
• Position 15: Glycine replaced with Alanine — enhances stability
• Position 27: Methionine replaced with Leucine — prevents methionine oxidation

These substitutions extend the half-life of the base peptide (Modified GRF 1-29, also marketed separately as "CJC-1295 without DAC" or "Mod GRF") from approximately 7 minutes (native GHRH) to approximately 30 minutes.

The Drug Affinity Complex (DAC)

The DAC technology is the distinguishing feature. It consists of a maleimidopropionic acid (MPA) linker attached to a lysine residue of the peptide. After subcutaneous injection, this reactive group covalently binds to Cysteine-34 of circulating serum albumin through a thioether bond.

• Molecular weight (unconjugated): Approximately 3,367 Da
• Molecular weight (albumin-conjugated): Approximately 70,000 Da (peptide + albumin)
• Half-life (unconjugated Modified GRF): ~30 minutes
• Half-life (DAC-conjugated, albumin-bound): ~6-8 days

The albumin binding achieves half-life extension through the same general principle as PEGylation and fatty acid conjugation (as used in semaglutide) — shielding from proteolytic degradation and reducing renal clearance by dramatically increasing the effective molecular size.

Mechanism of Action

GHRH Receptor Activation

CJC-1295 DAC acts through the GHRH receptor (GHRH-R) on anterior pituitary somatotroph cells. Receptor binding activates:

• Adenylyl cyclase and cAMP production
• Protein kinase A (PKA) signaling cascade
• GH gene transcription and protein synthesis
• GH granule exocytosis (GH release)

This pathway is distinct from the GHS-R1a pathway activated by GHRPs like hexarelin, which is why combining GHRH analogs with GHRPs produces synergistic GH release.

Sustained vs. Pulsatile Release

A critical pharmacological distinction: native GH physiology is pulsatile, with discrete secretory bursts separated by periods of low GH. CJC-1295 DAC, due to its extended duration, produces a continuous stimulus on pituitary somatotrophs rather than mimicking natural pulsatile patterns.

The biological implications of sustained versus pulsatile GH release are not fully resolved. Some evidence suggests that pulsatile patterns are important for:

• Optimal hepatic IGF-1 production
• Maintaining GH receptor sensitivity
• Sexually dimorphic gene expression in the liver
• Avoiding GH receptor desensitization

Whether sustained GHRH stimulation via CJC-1295 DAC produces physiologically equivalent effects to pulsatile GH release remains an open question in the research literature.

Clinical Research

Phase I/II Trial Data

ConjuChem conducted clinical trials that generated the most substantive human data available for this compound:

GH Response:

• Single subcutaneous doses (30-60 mcg/kg) produced sustained GH elevation lasting 6-14 days
• Mean GH levels increased 2-10 fold above baseline
• GH pulsatility was preserved to some degree (the sustained stimulus amplified existing pulses rather than creating a completely flat GH profile)

IGF-1 Response:

• IGF-1 levels increased by 1.5-3 fold above baseline
• Elevation persisted for up to 14 days following a single injection
• Multiple weekly doses produced cumulative IGF-1 elevation

Body Composition:

• Short-term studies showed trends toward increased lean body mass and reduced fat mass, though study durations were insufficient for definitive body composition outcomes

Pharmacokinetic Profile

Parameter	Value
Tmax (peptide)	2-4 hours
Terminal half-life	6-8 days
Duration of IGF-1 elevation	10-14 days
Dosing frequency in trials	Once or twice weekly
Bioavailability (subcutaneous)	High (albumin binding occurs rapidly post-injection)

Safety Data from Clinical Trials

Adverse events reported in clinical studies:

• Injection site reactions (redness, swelling) — common
• Transient flushing and warmth — common
• Headache — occasional
• Diarrhea — occasional
• Transient water retention — reported at higher doses
• No serious adverse events attributed to CJC-1295 DAC in published trial data

Comparison: CJC-1295 DAC vs. Modified GRF (1-29)

Parameter	CJC-1295 DAC	Modified GRF (1-29)
Half-life	6-8 days	~30 minutes
Dosing frequency	Weekly or twice weekly	Multiple times daily
GH release pattern	Sustained elevation with amplified pulses	Acute pulse, returns to baseline within hours
IGF-1 elevation	Prolonged (10-14 days)	Transient (hours)
Physiological pattern	Less pulsatile	More closely mimics natural pulsatility
Convenience	High (infrequent dosing)	Lower (frequent dosing required)
Clinical data	Phase II trials completed	Limited formal clinical data
Tachyphylaxis risk	Theoretical concern with sustained stimulation	Lower risk with pulsatile approach

The choice between these two forms involves a trade-off between dosing convenience (DAC version) and physiological fidelity (non-DAC version).

Synergy with GHRPs

Consistent with the broader principle of GHRH + GHRP synergy, CJC-1295 DAC is often discussed in the context of combination use with GHRPs. The rationale:

• CJC-1295 DAC provides sustained background GHRH receptor activation
• Concurrent GHRP use (e.g., ipamorelin, GHRP-2) provides additional GHS-R1a stimulation and somatostatin suppression
• The combination may produce greater GH release than either compound alone

However, formal clinical trials evaluating CJC-1295 DAC in combination with specific GHRPs have not been published. The synergy principle is extrapolated from studies of other GHRH + GHRP combinations.

Key Considerations

Pulsatile vs. Sustained GH Stimulation

The fundamental question surrounding CJC-1295 DAC is whether sustained GHRH stimulation is preferable to, equivalent to, or inferior to pulsatile stimulation for specific physiological outcomes. The convenience of weekly dosing must be weighed against the departure from natural GH release kinetics.

Somatotroph Desensitization

Sustained GHRH receptor stimulation raises theoretical concerns about receptor downregulation or somatotroph exhaustion. Clinical data from the limited trial period did not show clear evidence of desensitization, but long-term effects remain unknown.

IGF-1 Monitoring

The prolonged IGF-1 elevation produced by CJC-1295 DAC means that IGF-1 levels may remain elevated for extended periods. Chronic elevation of IGF-1 has theoretical implications for cellular proliferation that have been discussed in the context of long-term safety.

Manufacturing and Identity

The DAC conjugation adds manufacturing complexity. Users of research-grade CJC-1295 should verify the presence of the DAC moiety through appropriate analytical testing, as the unconjugated form (Modified GRF 1-29) is a distinct compound with very different pharmacokinetics. Mass spectrometry can confirm molecular weight and the presence of the MPA-DAC linker.

Dosing Protocols

The following dosing information is compiled from published research and community discussion for educational purposes only. No FDA-approved human dosing guidelines exist for most research peptides. Always consult a qualified healthcare professional.

Reconstitution

Parameter	Value
Vial size	5 mg
Bacteriostatic water	2.0 mL
Concentration	2,500 mcg/mL
Storage (reconstituted)	2-8 °C, use within 2-4 weeks
Storage (lyophilized)	-20 °C

Dosing Schedule

Phase	Dose per injection	Frequency	Weekly total	Duration
Starting	300 mcg	2x per week	600 mcg	Weeks 1-2
Mid-range	500 mcg	2x per week	1,000 mcg	Weeks 3-4
Escalation	750 mcg	2x per week	1,500 mcg	Weeks 5-6
Target	1,000 mcg	2x per week	2,000 mcg	Weeks 7-12

Syringe Measurements (U-100 insulin syringe)

Dose	Units	Volume
300 mcg	12 units	0.12 mL
500 mcg	20 units	0.20 mL
750 mcg	30 units	0.30 mL
1,000 mcg	40 units	0.40 mL

Cycle Guidelines

• Cycle length: 8-12 weeks (up to 16 weeks)
• Route: Subcutaneous injection
• Spacing: 3-4 days between injections (e.g., Monday/Thursday)
• Injection sites: Rotate between abdomen, thighs, and upper arms
• Note: The DAC moiety extends the half-life to 8+ days, allowing twice-weekly dosing rather than the daily dosing required for non-DAC CJC-1295

Current Status

CJC-1295 DAC has not received FDA or EMA approval. ConjuChem's clinical program did not advance beyond Phase II, and the company shifted focus. The compound remains available as a research peptide. Its Phase II clinical data, while limited in scope and duration, represents some of the most robust human pharmacological data available for any non-approved GH secretagogue and provides a foundation for understanding the pharmacology of sustained GHRH receptor activation.