CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH) — the hypothalamic peptide that stimulates HGH secretion from the pituitary. Unlike compounds that directly provide exogenous HGH, CJC-1295 works upstream, stimulating the pituitary’s own HGH production. This distinction has significant implications for the physiological pattern of HGH release and has made CJC-1295 a notable tool in growth hormone axis research.
GHRH: The Starting Point
To understand CJC-1295, you first need to understand native GHRH. Growth Hormone-Releasing Hormone is a 44-amino acid peptide produced by neurons in the arcuate nucleus of the hypothalamus. It travels via the hypothalamo-pituitary portal blood system to the anterior pituitary, where it binds to GHRH receptors on somatotrophs and stimulates HGH synthesis and secretion.
Native GHRH has significant limitations as a research tool: it has a very short plasma half-life (under 10 minutes), is rapidly degraded by the enzyme DPP-IV (dipeptidyl peptidase IV), and requires frequent administration to maintain biological effect. The first generation of GHRH analogues addressed the DPP-IV vulnerability by substituting the alanine at position 2 — but these early analogues still had short half-lives due to renal clearance.
CJC-1295: Structure and the DAC Technology
CJC-1295 is specifically the form of the GHRH analogue incorporating Drug Affinity Complex (DAC) technology. The DAC modification involves a maleimidoproprionic acid (MPA) group linked to the peptide that enables covalent binding to circulating albumin — similar in principle to the fatty acid modification used in GLP-1 analogues, but through a reactive covalent bond rather than non-covalent association.
| Item | Detail |
| Base peptide | GHRH(1-29) with substitutions for DPP-IV resistance |
| Key modification | DAC (Drug Affinity Complex) — maleimide group for covalent albumin binding |
| Half-life result | Extended to approximately 6-8 days in research models |
| Molecular weight | ~3367 Da |
| CAS Number | 863288-34-0 |
| Mechanism | GHRH receptor agonism → pituitary somatotroph stimulation → HGH release |
The covalent albumin binding achieved by the DAC modification dramatically extends CJC-1295’s half-life compared to native GHRH or first-generation analogues. Once the maleimide group reacts with the thiol group on albumin’s cysteine-34 residue, the peptide is effectively carried by albumin throughout its normal circulation lifetime.
CJC-1295 Without DAC: A Distinction That Matters
An important and often confused distinction exists between CJC-1295 with DAC and ‘CJC-1295 without DAC’ — which is actually a different compound sometimes called Modified GRF(1-29) or Mod GRF. Without the DAC modification, the peptide has a much shorter half-life (approximately 30 minutes) and produces a more acute, pulse-like HGH release. With DAC, the extended half-life produces more sustained HGH elevation over days.
These two profiles have different research applications: Mod GRF(1-29) is used in research that aims to study acute GH pulse characteristics, while CJC-1295 (with DAC) is used in research examining sustained stimulation of the GH axis. Conflating the two in research contexts leads to significant interpretive errors.
Research Findings on GH Axis Stimulation
Human research with CJC-1295 (with DAC) has documented dose-dependent increases in plasma HGH and IGF-1 levels following administration. Key findings from early research include sustained elevation of IGF-1 lasting 9-11 days from a single dose, and HGH increases of 2-10 fold above baseline depending on dose, with the pulsatile nature of HGH secretion preserved rather than converted to a constant elevation.
The preservation of pulsatile HGH secretion is considered an important feature in research — it suggests CJC-1295 amplifies existing pituitary pulses rather than overriding normal regulatory architecture. This distinguishes it mechanistically from exogenous HGH administration, which replaces endogenous pulses with a continuous exogenous supply and suppresses natural pituitary output.
Research Context: GHRH Analogues vs Exogenous HGH
A key research question in the HGH field has been whether stimulating endogenous GH production (as GHRH analogues do) produces different biological outcomes from providing exogenous HGH directly. The theoretical arguments for expecting differences are sound: natural pulsatile release patterns are preserved with GHRH stimulation, negative feedback remains intact, and other co-secreted factors from the pituitary maintain their normal patterns.
Research examining this question in GH-deficient models and in ageing animal systems has reported qualitative differences in certain biological outcomes between GHRH-stimulated endogenous HGH and exogenous HGH administration — supporting the hypothesis that the pattern of HGH delivery, not just the total amount, matters for downstream biology.
CJC-1295 is a research tool for studying the effects of sustained GHRH receptor activation and GH axis stimulation — not a source of exogenous HGH. This mechanistic distinction defines its research applications and differentiates its biological effects from direct HGH administration.