CJC-1295

Overview

CJC-1295 (with DAC) is a synthetic analog of growth hormone-releasing hormone (GHRH). It consists of the first 29 amino acids of GHRH with a small set of modifications. Those modifications are designed to extend the duration of action. The compound is studied in the context of growth hormone signalling and sustained endocrine activity.

One modification defines this variant: the DAC group. DAC stands for Drug Affinity Complex. It is a maleimidopropionyl-lysine moiety attached to the end of the chain. The group binds covalently to serum albumin, a carrier protein in blood. Through that binding, the compound stays in circulation much longer than native GHRH, with a half-life on the order of several days.

This is the key distinction from CJC-1295 without DAC, also known as Modified GRF (1-29). That variant lacks the DAC group and has a half-life of minutes rather than days. Online sources often conflate the two, but they differ materially in molecular weight and pharmacokinetic behaviour. They are not interchangeable in research design. A separate entry describes the no-DAC variant.

Early human pharmacokinetic data exist for CJC-1295 with DAC. Large controlled clinical studies with functional endpoints are absent, however. Conclusions about translational relevance therefore call for caution.

Mechanism of action

CJC-1295 acts on the GHRH receptor (GHRH-R). The receptor sits on somatotroph cells in the anterior pituitary. Its activation stimulates the synthesis and release of growth hormone. The modified structure makes the compound more resistant to enzymatic breakdown. As a result, the receptor stays engaged longer than it would under native GHRH.

GHRH receptor activation

• Binding to the GHRH receptor on somatotroph cells of the anterior pituitary.
• Stimulation of growth hormone synthesis and pulsatile release.
• Complementary to a separate pathway, the GHS receptor (GHS-R1a), through which compounds such as Ipamorelin act.

Extended duration of action

• The modified amino acid structure confers resistance to degradation by the enzyme DPP-IV.
• The DAC group binds to albumin. This extends the time the compound remains in circulation to several days.
• The signalling window is therefore longer than that of native GHRH.

Pharmacological context

• Shifts in hormonal markers do not automatically translate into broader physiological conclusions.
• A longer-acting signalling profile makes dose-response interpretation more complex.
• Downstream effects of sustained GHRH-R activation require further characterisation.

Research findings

• In one human study, subcutaneous administration produced dose-dependent increases in growth hormone and IGF-1, a growth factor driven by growth hormone.
• In preclinical models, sustained elevation of growth hormone and IGF-1 was observed.
• The DAC variant shows an extended half-life compared with native GHRH; in the human study it was estimated at 5.8 to 8.1 days.
• Early human pharmacokinetic data show an extended activity window.
• Additive or synergistic effects have been described in research models combining the compound with agents acting through the GHS receptor.

Growth hormone axis

• In a human study, subcutaneous administration produced a dose-dependent increase in growth hormone and IGF-1, a growth factor driven by growth hormone.
• In preclinical models, sustained elevation of growth hormone and IGF-1 was observed.

Pharmacokinetics

• The DAC variant shows an extended half-life relative to native GHRH. In the human study it was estimated at 5.8 to 8.1 days.
• Early human pharmacokinetic data demonstrate an extended activity window.

Combination research

• Additive or synergistic effects have been described in research models combining the compound with agents acting through the GHS receptor.

Research context

CJC-1295 with DAC has been studied in both preclinical and limited early human settings. Its pharmacokinetic profile has generated considerable interest in endocrine research. That is particularly true for the extended half-life of the DAC variant.

The compound is often discussed alongside agents acting through the GHS receptor, such as Ipamorelin. A distinction matters here: mechanistic interest is not the same as evidence maturity. The available human data come from one randomised study with hormonal outcome measures, not from studies with clinical endpoints.

Confusion between the DAC and no-DAC variants is common in online discussion. That distinction is important when evaluating sources. The two variants differ in pharmacokinetic behaviour and are not interchangeable in research design.

Open questions

Pharmacological interest is well-supported, but translational certainty for humans remains limited.

• Human outcome data beyond pharmacokinetic measures are limited. For clinical research groups this points to a next step: studies with functional endpoints rather than hormonal markers alone.
• Online sources frequently conflate the DAC and no-DAC contexts. Clearer, explicit reporting of which variant was used would improve comparability across studies.
• Varied protocol contexts complicate cross-study comparison. Standardised research designs would address this.
• The long-term profile of sustained GHRH-R activation has not been fully characterised. Longitudinal research would help to fill that gap.
• Dosing frameworks and combination protocols are not well established. Comparative work under controlled conditions is a logical next step.

Research outlook

Controlled human trials with functional and clinical endpoints beyond hormonal markers.

Comparative studies between the DAC and no-DAC variants under standardised conditions.

Investigation of combination protocols with agents acting through the GHS receptor in defined research models.

Long-term safety assessment of sustained GHRH-R activation.

Clarification of the relationship between elevated growth hormone and IGF-1 levels and downstream physiological outcomes.

Scientific interest

Extended duration of action through albumin binding: the DAC group binds covalently to serum albumin, a distinguishing pharmacokinetic mechanism among GH-axis peptides.

Resistance to enzymatic breakdown: the modified structure withstands DPP-IV, which prolongs the duration of action.

Complementary receptor pathway: much studied alongside agents acting through the GHS receptor, with a different point of engagement.

Model compound for sustained endocrine signalling: relevant for research on the GH axis, recovery biology and body composition.

Specifications

References

1. Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog · Jetté L, Léger R, Thibaudeau K, et al. · Endocrinology · 2005
2. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults · Teichman SL, Neale A, Lawrence B et al. · Journal of Clinical Endocrinology & Metabolism · 2006
3. Advances in the detection of growth hormone releasing hormone synthetic analogs · Memdouh S, Gavrilović I, Ng K et al. · Drug Testing and Analysis · 2022
4. Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions · Renke G, Chinellato V. · International Journal of Molecular Sciences · 2026

Availability

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