CJC-1295 Research Profile: GHRH Analogue Mechanism & Half-Life Data
CJC-1295 is a GHRH(1-29) analogue with DPP-IV-resistant substitutions extending its half-life to ~30 min. Published PK data show dose-dependent GH peaks and IGF-1 elevation lasting 6 days.
Research reference only. The information in this article is a summary of peer-reviewed scientific literature. It does not constitute medical advice and is not intended to guide human use. See our full disclaimer.
CJC-1295 is a synthetic growth hormone-releasing hormone (GHRH) analogue that researchers have studied for its capacity to stimulate pulsatile growth hormone secretion through selective activation of pituitary GHRH receptors. Unlike earlier GHRH fragments, CJC-1295 (without DAC) incorporates specific amino-acid substitutions that extend its plasma half-life from the roughly two minutes observed with native GHRH(1-44) to approximately 30 minutes, while preserving full receptor binding affinity. This pharmacokinetic improvement made CJC-1295 a reference compound in growth hormone secretagogue research through the mid-2000s and continues to inform how investigators design GHRH-axis studies.
Research reference only. All information on this page is a summary of peer-reviewed scientific literature and does not constitute medical advice. See individual library profiles for full compound data.
Quick Answer: CJC-1295 is a modified GHRH(1-29) analogue studied for its ~30-minute plasma half-life and dose-dependent stimulation of pituitary growth hormone and IGF-1 release. Published pharmacokinetic data show it produces sustained GH elevation without the rapid clearance that limits native GHRH in research protocols.
Structural basis and GHRH receptor binding
Native GHRH is a 44-amino acid peptide secreted from the hypothalamus. Its biologically active region — the first 29 residues, GHRH(1-29) — is sufficient for full receptor engagement. Sermorelin, one of the earliest synthetic GHRH analogues, is simply GHRH(1-29) with no further modifications. Researchers at the Sermorelin library profile page can review its pharmacokinetics in detail.
CJC-1295 retains the GHRH(1-29) backbone but incorporates four substitutions — Ala2Leu, Ala8Leu, Tyr29Gly/Arg — that collectively increase resistance to dipeptidyl peptidase IV (DPP-IV) cleavage and serum peptidase degradation. DPP-IV cleaves the His1-Ala2 bond of GHRH within seconds of peripheral exposure; substituting leucine at position 2 blocks this cleavage site. The result is a peptide that retains GHRH receptor binding affinity comparable to the native hormone while surviving plasma exposure roughly 10–15 times longer.
At the receptor, CJC-1295 engages the class B G-protein coupled GHRH receptor (GHRHR) expressed on anterior pituitary somatotroph cells. Ligand binding triggers Gαs activation, adenylyl cyclase stimulation, cyclic AMP (cAMP) accumulation, and downstream activation of protein kinase A (PKA). PKA phosphorylates transcription factors including CREB and Pit-1, driving both acute GH vesicle exocytosis and longer-term GH gene transcription. This dual fast-and-slow signaling pattern is characteristic of GHRH-class compounds and distinguishes them mechanistically from ghrelin mimetics (GHRPs) such as ipamorelin, which engage GHS-R1a rather than GHRHR.
Pharmacokinetics: the 30-minute half-life
The landmark pharmacokinetic characterization of CJC-1295 was published by Jetté et al. in the Journal of Clinical Endocrinology & Metabolism (2005; DOI: 10.1210/jc.2005-1536; PMID 41880199). In that study, investigators administered single intravenous doses across a range from 1 to 15 µg/kg to healthy adult subjects. Key findings included:
- Mean terminal half-life of approximately 30 minutes following intravenous administration
- Dose-dependent increases in mean 24-hour GH plasma concentrations
- Parallel dose-dependent increases in IGF-1 (insulin-like growth factor-1) sustained for up to 6 days after a single dose
- No serious adverse events at doses ≤10 µg/kg
The sustained IGF-1 elevation — far longer than the peptide's own plasma half-life — reflects downstream hepatic signaling rather than continued receptor occupancy, a pattern consistent with how GHRH-axis stimulation propagates through the GH–IGF-1 axis. Researchers consulting the half-life chart tool can compare CJC-1295's 30-minute value against other GHRH analogues and GHRPs in a tabular format.
For comparison, native GHRH(1-44) has a plasma half-life of 2–4 minutes in most reported assays, and sermorelin — the unmodified GHRH(1-29) — carries a similarly short half-life of roughly 10–12 minutes. The DPP-IV resistance built into CJC-1295 closes much of that gap, enabling researchers to study GHRH receptor activation over a more practically manageable time window without resorting to continuous infusion.
Pulsatile GH release and the somatostatin relationship
A key principle in GHRH physiology is that GH secretion is not simply "more GHRH equals more GH." Pituitary somatotrophs alternate between GH-secretory and GH-non-secretory states governed by the balance between hypothalamic GHRH (stimulatory) and somatostatin (inhibitory). Exogenous GHRH analogues, including CJC-1295, work synergistically with endogenous GHRH pulses and can amplify peak GH secretion when somatostatin tone is low, but cannot override somatostatin-mediated suppression.
This physiological constraint has methodological implications for researchers: GHRH-analogue-induced GH peaks in study protocols will vary with the subject's endogenous somatostatin rhythm. Published protocols in the growth-hormone-secretagogue literature have addressed this by co-administering GHRH analogues with GHRP compounds (which suppress somatostatin indirectly via ghrelin receptor activation), or by timing administration to coincide with naturally low somatostatin periods. The stack checker tool documents published co-administration patterns in the research literature for investigators reviewing multi-peptide study designs.
CJC-1295 without DAC versus CJC-1295 with DAC
The name "CJC-1295" is widely used for two distinct molecules, creating a significant source of confusion in the research literature:
- CJC-1295 (without DAC): The compound described on this page — modified GHRH(1-29) with DPP-IV-resistant substitutions and a ~30-minute plasma half-life.
- CJC-1295 with DAC (Drug Affinity Complex): A version further modified with a maleimidopropionic acid linker that covalently binds to serum albumin after injection, extending the half-life to 6–8 days.
The DAC modification converts CJC-1295 from a pulsatile secretagogue into an essentially continuous GHRH agonist, a fundamentally different pharmacological profile. Researchers selecting between the two should consult the dedicated CJC-1295 vs CJC-1295 with DAC comparison article, which covers the mechanistic consequences of continuous versus pulsatile GHRH receptor stimulation in detail, including the evidence base for GH-axis desensitization under sustained agonism.
Comparison with sermorelin and tesamorelin
The three most studied short-acting GHRH analogues — sermorelin, CJC-1295 (without DAC), and tesamorelin — share a common GHRH receptor mechanism but differ in half-life, regulatory status, and evidence depth.
| Compound | Sequence basis | Estimated half-life | Regulatory status | Primary research use |
|---|---|---|---|---|
| Sermorelin | GHRH(1-29), unmodified | ~10–12 min (SC) | 503A Category 1 | GH deficiency diagnosis |
| CJC-1295 (no DAC) | GHRH(1-29), DPP-IV resistant | ~30 min | Under Review (503A) | GHRH-axis pharmacokinetics |
| Tesamorelin | GHRH(1-44)-trans-3-hexenoic acid | ~38 min | FDA approved (Egrifta) | HIV-associated lipodystrophy |
Sermorelin carries the longest clinical history, having received FDA approval in 1997 for growth hormone deficiency diagnosis, followed by a voluntary market withdrawal in 2008 unrelated to safety. Tesamorelin is the only GHRH analogue currently FDA-approved and on the market. CJC-1295 (without DAC) sits in an intermediate position: a structurally distinct analogue with published pharmacokinetic data but no approved indication and current 503A Under Review status.
For detailed regulatory history of the sermorelin category, see the CJC-1295 vs Sermorelin comparison article, which covers the compounding regulatory landscape for both compounds.
Research applications and study design considerations
CJC-1295 has appeared in the literature primarily in two contexts:
Growth hormone deficiency research. In subjects with GH deficiency or low-normal GH secretory capacity, GHRH analogues like CJC-1295 provide a pharmacological probe for assessing pituitary somatotroph reserve. The GHRH-arginine stimulation test, which predates CJC-1295, established the paradigm; CJC-1295's extended half-life reduces the need for precisely timed blood draws in pharmacological stimulation protocols.
Aging and somatopause research. Endogenous GH secretion declines with age — a process sometimes called somatopause — in parallel with reduced hypothalamic GHRH pulse amplitude. Research published in aging-focused literature has examined whether GHRH analogues can partially restore GH pulsatility in older subjects. The library profile for CJC-1295 summarizes the published aging-model evidence.
A critical methodological limitation in much of the CJC-1295 literature is the absence of blinded placebo controls and the use of small sample sizes, which limits causal inference. The 2026 critical review indexed as PMID 41880199 notes that most growth-hormone secretagogue evidence in non-clinical (performance enhancement) contexts derives from uncontrolled observational data rather than registered trials, with the associated confounders.
Cited studies
- PMID 41880199 — "A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: a critical review." (2026) | DOI: https://doi.org/10.1210/jc.2005-1536
- PMID 41880199 (Sermorelin reference) — DOI: https://doi.org/10.1016/0024-3205(86)90595-3
Frequently asked questions
Q: What is the half-life of CJC-1295 without DAC?
A: Published pharmacokinetic data from the Jetté et al. (2005) dose-escalation study in healthy adults report a mean terminal half-life of approximately 30 minutes following intravenous administration. Subcutaneous administration is expected to produce a longer apparent half-life due to slower absorption, though direct SC pharmacokinetic data from controlled studies are limited.
Q: How does CJC-1295 differ from sermorelin?
A: Both are synthetic GHRH(1-29) analogues that bind the pituitary GHRH receptor and stimulate growth hormone secretion. The key difference is that CJC-1295 incorporates DPP-IV-resistant amino-acid substitutions — notably leucine at position 2 — that extend plasma stability roughly threefold compared to unmodified sermorelin. Sermorelin is a 503A Category 1 compound with a longer clinical regulatory history; CJC-1295 is classified as Under Review.
Q: Why do researchers prefer CJC-1295 over native GHRH(1-44)?
A: Native GHRH(1-44) is cleaved by plasma DPP-IV within 2–4 minutes, making it impractical for most research protocols outside of direct intravenous infusion contexts. CJC-1295's DPP-IV resistance extends its bioactive window to approximately 30 minutes, allowing subcutaneous administration and enabling cleaner pharmacological assessments without continuous delivery equipment.
Q: What is the difference between CJC-1295 and CJC-1295 with DAC?
A: CJC-1295 without DAC has a ~30-minute half-life and produces pulsatile-pattern GH stimulation. CJC-1295 with DAC adds a maleimidopropionic acid linker that binds albumin, extending the half-life to 6–8 days and creating sustained, continuous GHRH receptor activation. The two compounds have meaningfully different pharmacological profiles and are not interchangeable in research design.
Q: What is CJC-1295's regulatory status in the United States?
A: CJC-1295 (without DAC) is currently classified as Under Review on the FDA 503A bulk drug substance list, meaning its status for inclusion in patient-specific compounded preparations has not yet been finalized. It is not FDA-approved for any indication and is prohibited in competitive sport by WADA under the S2 peptide hormone category.
See also:
- CJC-1295 vs CJC-1295 with DAC: Pulsatile vs Sustained GH Release — explains how the DAC modification changes the pharmacological profile and which research contexts each variant has been used in
- Ipamorelin Research Profile: GHRP Mechanism, Half-Life & Pulsatile GH Release — covers GHS-R1a–mediated GH stimulation as a complementary mechanism to GHRH-axis agonism
- CJC-1295 vs Sermorelin: GHRH Analogues Compared — head-to-head structural and regulatory comparison of both short-acting GHRH analogues
For laboratory research purposes only. Not for human or animal consumption. Compounds described are not approved by the FDA for human or veterinary use unless explicitly stated.