CJC-1295
Also known as: CJC-1295 DAC, Modified GRF 1-29, Drug Affinity Complex
CJC-1295 is a synthetic analog of growth hormone releasing hormone (GHRH) with a Drug Affinity Complex that extends its half-life significantly compared to native GHRH.
Key Findings at a Glance
- • The Drug Affinity Complex modification allows CJC-1295 to covalently bond to serum albumin after injection, extending its half-life from minutes to 6 to 8 days.
- • A single injection of CJC-1295 with DAC can elevate IGF-1 levels for up to two weeks, a duration unmatched by any other GHRH analog studied in clinical settings.
- • CJC-1295 combined with a GHRP such as Ipamorelin or GHRP-6 produces 2 to 5 times more growth hormone than either peptide alone, due to activation of complementary pituitary pathways.
- • CJC-1295 exists in two distinct forms with vastly different pharmacokinetics: the DAC version acts for days, while Modified GRF 1-29 without DAC has a half-life of only 30 minutes.
CJC-1295 Overview & Molecular Profile
CJC-1295 is a synthetic GHRH analog built on the first 29 amino acids of GHRH with a Drug Affinity Complex (DAC) lysine modification that enables covalent binding to serum albumin. This albumin binding extends the half-life from minutes to 6–8 days, enabling once-weekly dosing with sustained GH and IGF-1 elevation. First described in a 2006 JCEM study, it exists in two forms: with DAC (long-acting) and without DAC (Modified GRF 1-29; ~30-minute half-life).
Mechanism of Action: Hormonal Signaling & Receptor Binding
CJC-1295 acts on the GHRH receptor in the pituitary gland to stimulate growth hormone release. The DAC modification allows the peptide to bind covalently to serum albumin after injection, protecting it from enzymatic degradation and extending its biological half-life from minutes to days. This results in sustained elevation of GH and IGF-1 levels. The peptide amplifies the natural GH pulsatile release pattern rather than creating artificial spikes.
Drug Affinity Complex: Engineering a 6-8 Day GHRH Analog
CJC-1295 represents a unique approach to peptide half-life extension: covalent albumin conjugation via a Drug Affinity Complex (DAC). Unlike the reversible albumin binding used by GLP-1 agonists, the DAC forms an irreversible bond with serum albumin, creating a circulating depot that extends the half-life of a GHRH analog from minutes to days.
The DAC Covalent Albumin-Binding Mechanism
The Drug Affinity Complex technology was specifically developed to overcome the rapid degradation of GHRH analogs, which have half-lives measured in minutes without modification.
- • A maleimidopropionyl-lysine linker reacts with Cys34 on serum albumin after subcutaneous injection, forming an irreversible thioether covalent bond. This conjugation extends the half-life from approximately 30 minutes (for unmodified Mod GRF 1-29) to 6-8 days.
- • A single subcutaneous dose produces dose-dependent GH elevation sustained over the full 6-8 day half-life period, with IGF-1 elevation persisting up to 14 days (approximately 2x baseline).
- • Without DAC (marketed as Mod GRF 1-29 or Modified GRF), the peptide retains the same GHRH receptor agonist activity but requires 2-3 daily administrations due to the ~30-minute half-life.
Pulsatile GH Amplification, Not Constant Elevation
A critical distinction in CJC-1295's pharmacodynamics is that it amplifies the body's natural pulsatile GH secretion rather than creating a constant, non-physiologic GH level.
- • CJC-1295 enhances the amplitude of endogenous GH pulses — each natural GH secretory episode is amplified by the persistent GHRH receptor stimulation, rather than being replaced by a flat, elevated GH concentration.
- • This preservation of pulsatility distinguishes CJC-1295 from exogenous GH administration, which suppresses endogenous GH pulsatility through negative feedback.
- • The combination of CJC-1295 (GHRH analog) with a GHRP such as Ipamorelin (GHSR-1a agonist) produces synergistic GH release — the two receptor pathways converge on the somatotroph to produce GH secretion greater than either agent alone.
CJC-1295 Pharmacokinetics: DAC vs Non-DAC Half-Life Comparison
Figure: CJC-1295 with DAC (blue) maintains plasma levels for 6-8 days via covalent albumin binding, enabling weekly dosing. Without DAC (Mod GRF 1-29, red dashed) the peptide clears within hours, requiring 2-3 daily injections. Based on published clinical PK data (PMID: 16352683).
Research-Observed Effects
Sustained GH Elevation
Extensive ResearchResearch demonstrates that CJC-1295 with DAC produces remarkably prolonged elevation of growth hormone levels lasting 6-8 days following a single subcutaneous injection, fundamentally different from the short-lived pulses produced by other GH-releasing compounds. The Drug Affinity Complex binds covalently to albumin in the bloodstream, protecting the peptide from enzymatic degradation and extending its biological activity dramatically. Studies show 2-10 fold elevations in mean GH levels that persist throughout the week, while importantly maintaining the natural pulsatile secretion pattern rather than creating unnatural constant elevation. This sustained release profile has made CJC-1295 valuable for research into growth hormone replacement strategies, aging-related GH decline, and optimization of GH therapy protocols. The extended half-life also enables study of long-term GH elevation effects without the confounding variable of repeated daily injections.
IGF-1 Increase
Extensive ResearchClinical studies demonstrate significant and sustained increases in Insulin-like Growth Factor-1 (IGF-1) levels following CJC-1295 administration, with elevations persisting for days to weeks depending on the dosing protocol. IGF-1, produced primarily by the liver in response to growth hormone, mediates many of GH's anabolic and metabolic effects throughout the body. Research shows dose-dependent IGF-1 increases ranging from 50% to 200% above baseline, with effects on tissue regeneration, protein synthesis, and cellular growth pathways. The sustained IGF-1 elevation profile makes CJC-1295 particularly valuable for studying the effects of chronic IGF-1 exposure on muscle metabolism, bone formation, and age-related tissue decline. Studies have documented maintained IGF-1 elevation for up to 2 weeks following a single CJC-1295 administration in some protocols.
Body Composition Research
Moderate ResearchResearch indicates CJC-1295 may influence body composition through multiple GH and IGF-1 mediated pathways including enhanced lipolysis (fat breakdown), increased lean body mass, and improved protein synthesis in skeletal muscle tissue. Studies have documented potential reductions in visceral adipose tissue (abdominal fat), which is associated with metabolic disease risk, along with improvements in fat-free mass. The peptide has been investigated for obesity research applications, sarcopenia (age-related muscle loss) prevention studies, and metabolic syndrome investigations. Long-term animal studies suggest favorable body composition changes including reduced body fat percentage and increased muscle mass without the water retention sometimes associated with direct GH administration. These findings have implications for research into healthy aging, athletic performance optimization, and metabolic health.
Sleep Quality Studies
Preliminary ResearchPreliminary research suggests CJC-1295 may improve sleep architecture, particularly enhancing slow-wave (deep) sleep phases when natural growth hormone release peaks occur. Studies indicate that optimized GH pulsatility achieved through GHRH analog administration may support the natural relationship between deep sleep and growth hormone secretion. Research has documented improvements in subjective sleep quality measures and potential enhancement of recovery processes associated with quality sleep. These findings have implications for aging research where both sleep quality and GH production naturally decline, as well as for recovery optimization studies in athletic and rehabilitation contexts. The sustained GH elevation may support overnight recovery and tissue repair processes.
Synergistic GHRP Combination
Moderate ResearchExtensive research demonstrates that CJC-1295 produces synergistic effects when combined with growth hormone releasing peptides such as Ipamorelin or GHRP-6, resulting in substantially greater GH release than either compound alone. This synergy occurs because CJC-1295 acts on GHRH receptors while GHRPs act on ghrelin receptors, activating complementary pathways that amplify pituitary GH secretion. Studies document 2-5 fold greater GH release with combined administration compared to either peptide individually. This combination approach has become a standard research protocol for studying maximized natural GH secretion, optimal body composition effects, and the potential therapeutic applications of enhanced GH/IGF-1 axis activation.
Research Protocol Doses Reported in Published Literature
Research Disclaimer: Doses reported below are from published preclinical research protocols. CJC-1295 is not approved for human use by the FDA or any regulatory agency. This information is provided for research reference only and does not constitute a dosing recommendation.
| Route | Dose | Frequency | Notes |
|---|---|---|---|
| Subcutaneous (with DAC) | 30–60 mcg/kg | Once weekly or biweekly | Sustained GH/IGF-1 elevation for 6–8 days |
| Subcutaneous (without DAC) | 100–300 mcg | 2–3× daily | Modified GRF 1-29; t½ ~30 min; creates acute GH pulses |
| Intravenous (with DAC) | 30–60 mcg/kg | As per protocol | Used in clinical PK studies (PMID: 16352683) |
All doses above are reported from published research protocols using laboratory subjects. Refer to the cited studies in the Research Studies section above for original source data.
Research Studies & References
Prolonged stimulation of growth hormone and insulin-like growth factor 1 secretion by CJC-1295
Teichman SL, Neale A, et al.
Journal of Clinical Endocrinology & Metabolism (2006)
This landmark clinical study established CJC-1295's unique pharmacokinetic profile through comprehensive evaluation in healthy adult volunteers receiving single and multiple dose administrations. Researchers demonstrated that the Drug Affinity Complex modification enabled sustained growth hormone elevation lasting 6-8 days from a single injection, representing a major advancement over native GHRH with its minutes-long half-life. The study documented dose-dependent IGF-1 increases reaching 1.5-3 fold above baseline with effects persisting for up to 2 weeks. Safety analysis revealed excellent tolerability with injection site reactions being the most common adverse effect. The research established CJC-1295 as the first clinically viable long-acting GHRH analog and demonstrated its potential for once-weekly or less frequent dosing in GH replacement research protocols.
CJC-1295 combined with GHRP-6: Synergistic effects on growth hormone secretion
Alba M, Fintini D, et al.
Journal of Endocrinological Investigation (2008)
This important combination study evaluated the synergistic effects of CJC-1295 with GHRP-6 on growth hormone secretion patterns in both animal models and preliminary human trials. Researchers demonstrated that co-administration produced significantly greater GH release than either compound alone, with peak GH levels 2-5 times higher than single-agent treatment. The study provided mechanistic insight showing that activation of both GHRH and ghrelin receptor pathways simultaneously amplifies pituitary responsiveness and overcomes negative feedback inhibition. Pharmacokinetic analysis confirmed that the combination maintained CJC-1295's extended duration of action while adding the acute GH pulse characteristic of GHRP administration. These findings established the scientific basis for combination protocols now widely used in GH axis research.
Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog
Ionescu M, Frohman LA.
Journal of Clinical Endocrinology & Metabolism (2006)
Demonstrated that CJC-1295 amplifies endogenous GH pulsatility rather than producing constant GH elevation, preserving the physiologic secretory pattern during sustained GHRH receptor stimulation.
Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse
Alba M, Fintini D, Bowers CY, et al.
American Journal of Physiology - Endocrinology and Metabolism (2006)
Demonstrated that CJC-1295 normalizes growth in GHRH-deficient animals, confirming its mechanism of action through the GHRH receptor pathway and establishing dose-response characteristics.
Evaluation of pulsatile patterns of growth hormone release in humans: A brief review
Hartman ML, Iranmanesh A, Thorner MO, Veldhuis JD.
American Journal of Human Biology (1993)
Comprehensive review of GH pulsatile secretion patterns in humans, establishing the physiological framework for understanding how GH secretagogues interact with endogenous pulse generation.
Comparative Research
Explore in-depth research analyses and comparative studies featuring CJC-1295.
Comparative Clinical Analysis
CJC-1295 vs Ipamorelin: GHRH Analog vs GHRP Comparison for Growth Hormone Research
CJC-1295 and Ipamorelin represent two complementary mechanisms for stimulating growth hormone release, which is why they are frequently combined in research settings. CJC-1295, a GHRH (growth hormone releasing hormone) analog, works at the pituitary to amplify the GH signal. Ipamorelin, a selective GHRP (growth hormone releasing peptide), works through the ghrelin receptor to stimulate GH release while being uniquely selective—not affecting cortisol or prolactin like other GHRPs. The combination produces synergistic GH elevation exceeding either peptide alone, making it the most popular peptide pairing for growth hormone research.
Sermorelin vs CJC-1295: GHRH Analog Comparison for Growth Hormone Research
Sermorelin and CJC-1295 are both GHRH analogs that stimulate pituitary GH release through the GHRH receptor, but differ dramatically in pharmacokinetics. Sermorelin is the natural GHRH (1-29) fragment with a short half-life (~10-20 minutes), requiring frequent dosing but producing physiological pulsatile GH patterns. CJC-1295, particularly with DAC (Drug Affinity Complex), has an extended half-life (~8 days), allowing weekly dosing but producing more sustained GH/IGF-1 elevation. Sermorelin has FDA approval history for pediatric GH deficiency, while CJC-1295 remains a research compound with more limited clinical data.
Frequently Asked Questions
What is the difference between CJC-1295 with DAC and without DAC?
CJC-1295 with DAC (Drug Affinity Complex) has a lysine modification that covalently binds to serum albumin, extending its biological half-life from minutes to 6–8 days. This allows once-weekly dosing and creates sustained GH/IGF-1 elevation. Without DAC (Modified GRF 1-29), CJC-1295 behaves like native GHRH with a ~30-minute half-life, requiring 2–3 daily injections to maintain effect. Researchers choose between them based on whether sustained elevation or pulsatile GH mimicry is desired.
What does the clinical evidence show for CJC-1295?
A published Phase I/II dose-escalation study in healthy adults (PMID: 16352683; JCEM 2006) found a single CJC-1295 with DAC injection produced dose-dependent GH increases (up to 2–10× baseline) and IGF-1 increases (up to 1.5–3× baseline) lasting 6–7 days in 66 subjects. This is one of the few GHRH analog peptides with published human clinical PK/PD data. Extended efficacy trials or regulatory approval have not followed.
How does CJC-1295 compare to Sermorelin?
Both are GHRH analogs activating the same pituitary GHRHR, but with different pharmacokinetics. Sermorelin uses only the first 29 amino acids of GHRH without stability modifications, giving it a ~10-minute half-life requiring nightly injection to leverage peak nocturnal GH release. CJC-1295 with DAC enables weekly dosing. Sermorelin has more published human data (FDA-approved historically for pediatric GH deficiency) but shorter duration. CJC-1295 offers convenience but carries concerns about sustained GHRHR stimulation.
Why is CJC-1295 often combined with Ipamorelin?
CJC-1295 and Ipamorelin activate complementary receptor pathways. CJC-1295 acts on the GHRH receptor, while Ipamorelin acts on the ghrelin receptor (GHSR-1a)—both on the same pituitary somatotroph cells. These pathways synergize: activation of one primes the cell to respond more strongly to the other. The combination produces GH release 2–5× greater than either compound alone, making it a common protocol in GH axis research.
Does CJC-1295 suppress natural GHRH secretion?
Sustained GHRHR activation by CJC-1295 with DAC could theoretically cause receptor downregulation or feedback suppression of endogenous GHRH release. The 2006 clinical study noted this theoretical concern but did not observe pituitary desensitization within its study window. Whether long-term use causes clinically meaningful GH axis suppression remains uncharacterized in published research.
What is the half-life of CJC-1295 without DAC?
CJC-1295 without DAC (Modified GRF 1-29) has a plasma half-life of approximately 30 minutes—far shorter than the DAC version's 6–8 days. This requires 2–3 daily injections to maintain GH stimulation. The benefit is that it creates discrete GH pulses more closely mimicking physiological pulsatility, which may be preferred in research models specifically studying GH pulsatility axis dynamics.
Is CJC-1295 approved for any medical use?
CJC-1295 is not approved for any medical use by any regulatory agency as of 2026. It is an investigational research peptide and should not be confused with Sermorelin, which was historically FDA-approved for pediatric GH deficiency. All CJC-1295 available commercially is for research use only and is not intended for clinical human administration.
What are the storage and stability requirements for CJC-1295?
Lyophilized CJC-1295 is stable at -20°C for extended periods. Once reconstituted in bacteriostatic water, it should be stored at 2–8°C and used within 2–4 weeks. The DAC modification provides additional stability compared to unmodified GHRH. Researchers should avoid repeated freeze-thaw cycles, which degrade both the peptide structure and the DAC albumin-binding moiety.
What combination protocols are most studied with CJC-1295?
The most commonly studied combination is CJC-1295 with Ipamorelin, pairing a GHRH analog (CJC-1295, stimulates somatotroph GHRH receptors) with a growth hormone secretagogue (Ipamorelin, stimulates GHSR-1a receptors). This combination exploits the synergistic interaction between the two receptor pathways on pituitary somatotrophs. Older protocols used CJC-1295 with GHRP-6 or GHRP-2, which are more potent but less selective. The GHRH+GHRP combination principle was established by Bowers et al. in the 1980s.
What biomarker should be monitored when studying CJC-1295 effects?
Serum IGF-1 (insulin-like growth factor 1) is the primary downstream biomarker for CJC-1295 activity. IGF-1 is produced by the liver in response to GH stimulation and has a longer half-life than GH itself (~15 hours vs ~20 minutes), making it a more stable and reproducible measurement. Expected IGF-1 elevation is 1.5-3x baseline at steady state with CJC-1295 + DAC. Blood draws should be taken at trough (immediately before the next scheduled dose) for consistency. GH itself can be measured but requires serial sampling due to its pulsatile nature.
Related Peptides
View allIpamorelin
Ipamorelin is a selective growth hormone secretagogue and ghrelin receptor agonist. It stimulates the release of growth hormone from the pituitary gland without significantly affecting cortisol or prolactin levels.
GHRP-6
GHRP-6 is a synthetic hexapeptide that stimulates growth hormone release through the ghrelin receptor. It was one of the first growth hormone releasing peptides developed.
GHRP-2
GHRP-2 is a synthetic growth hormone secretagogue that stimulates GH release through the ghrelin receptor. It is considered one of the most potent GHRPs for GH stimulation.
Sermorelin
Sermorelin is a synthetic analog of growth hormone releasing hormone (GHRH) containing the first 29 amino acids, which represent the active portion of the natural hormone.
IGF-1 LR3
IGF-1 LR3 is a modified form of insulin-like growth factor-1 with an arginine substitution at position 3 and a 13-amino acid N-terminal extension, designed to have reduced binding to IGF-binding proteins and an extended biological half-life.
Related Comparisons
CJC-1295 vs Ipamorelin
CJC-1295 and Ipamorelin represent two complementary mechanisms for stimulating growth hormone release, which is why they are frequently combined in research settings. CJC-1295, a GHRH (growth hormone releasing hormone) analog, works at the pituitary to amplify the GH signal. Ipamorelin, a selective GHRP (growth hormone releasing peptide), works through the ghrelin receptor to stimulate GH release while being uniquely selective—not affecting cortisol or prolactin like other GHRPs. The combination produces synergistic GH elevation exceeding either peptide alone, making it the most popular peptide pairing for growth hormone research.
Sermorelin vs CJC-1295
Sermorelin and CJC-1295 are both GHRH analogs that stimulate pituitary GH release through the GHRH receptor, but differ dramatically in pharmacokinetics. Sermorelin is the natural GHRH (1-29) fragment with a short half-life (~10-20 minutes), requiring frequent dosing but producing physiological pulsatile GH patterns. CJC-1295, particularly with DAC (Drug Affinity Complex), has an extended half-life (~8 days), allowing weekly dosing but producing more sustained GH/IGF-1 elevation. Sermorelin has FDA approval history for pediatric GH deficiency, while CJC-1295 remains a research compound with more limited clinical data.