A long-acting growth hormone releasing hormone analogue that significantly extends the half-life of GHRH through DAC (Drug Affinity Complex) technology.
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Buy Now →CJC-1295 is a synthetic analog of growth hormone releasing hormone (GHRH), the endogenous neuropeptide produced in the hypothalamus that stimulates the pituitary gland to secrete growth hormone (GH). The compound belongs to a class of research peptides that has attracted sustained scientific attention over the past two decades, largely because of its ability to extend the half-life of GHRH activity far beyond what natural or earlier synthetic analogs could achieve.
The peptide traces its origins to work done at ConjuChem Biotechnologies in Montreal, Canada, during the late 1990s and early 2000s. Researchers there were working on a Drug Affinity Complex (DAC) technology — a platform designed to covalently bind peptide drugs to circulating serum albumin, the most abundant plasma protein in human blood. Albumin has a long half-life of approximately 19 days and is protected from renal filtration by its size. By linking a peptide to albumin, researchers could dramatically extend the peptide’s circulation time, transforming what would otherwise be a compound with a half-life measured in minutes into one with activity lasting days.
The original GHRH molecule is a 44-amino acid peptide, though researchers established early on that the first 29 amino acids contain the full biological activity of the parent hormone. CJC-1295 itself is built on this 29-amino acid scaffold — specifically corresponding to GHRH(1-29) — with several strategic amino acid substitutions designed to improve metabolic stability. Most importantly, it incorporates a maleimidopropionic acid (MPA) bioconjugate linker at the C-terminus that, in the DAC-containing version, forms a permanent covalent bond with the lysine-525 residue of serum albumin. This version — correctly called CJC-1295 with DAC — has a reported half-life in animal models of 6 to 8 days, and in human pharmacokinetic studies, it elevated GH and IGF-1 levels for more than a week following a single injection.
A second variant, often labeled CJC-1295 without DAC or sometimes sold as Modified GRF(1-29), retains the stabilizing amino acid modifications but lacks the albumin-binding linker. Without DAC, this version behaves more like a short-acting GHRH analog, with a half-life in the range of 30 minutes to a few hours — closer to native GHRH but still considerably more stable. This distinction matters enormously in research design, as the two variants produce fundamentally different GH release patterns.
Compared to tesamorelin — a GHRH analog that reached FDA approval in 2010 for HIV-associated lipodystrophy — CJC-1295 with DAC sacrifices some of the pulsatile GH secretion that tesamorelin preserves, but achieves a far longer duration of action. The molecular weight of CJC-1295 (without DAC) is approximately 3,367 Da. As of 2025, CJC-1295 remains an investigational research compound with no FDA-approved indication, though it has been studied extensively in academic and preclinical settings.
CJC-1295 exerts its primary effects by binding to and activating the GHRH receptor (GHRH-R), a G protein-coupled receptor expressed predominantly on somatotroph cells in the anterior pituitary gland. When CJC-1295 engages GHRH-R, it triggers coupling to the stimulatory G protein (Gs), which activates adenylyl cyclase and drives an increase in intracellular cyclic AMP (cAMP). Rising cAMP activates protein kinase A (PKA), which phosphorylates downstream targets that promote both the synthesis and the exocytotic release of stored growth hormone.
Calcium influx through voltage-gated calcium channels also plays a role downstream of GHRH-R activation, contributing to the vesicular fusion events that release GH into portal circulation. The result is a GH pulse — a discrete burst of secretion rather than a steady tonic release — which is physiologically important because GH receptor sensitivity and downstream signaling in peripheral tissues depend on this pulsatile pattern. The CJC-1295 without DAC variant respects this pulsatility more closely, producing discrete GH pulses timed to injection. The DAC version, by contrast, produces a sustained low-to-moderate elevation in GH output over days, blunting peak-to-trough variation.
Crucially, CJC-1295 does not bypass the somatostatin brake. Somatostatin, the inhibitory counterpart to GHRH in the hypothalamic-pituitary axis, still modulates the height of GH pulses. This means the GH-releasing effect of CJC-1295 is subject to physiological regulation in a way that exogenous GH administration is not, which many researchers view as a meaningful safety distinction.
The DAC linker system built into the long-acting CJC-1295 variant represents a platform technology with broad applicability across peptide therapeutics. In the case of CJC-1295 with DAC, the maleimidopropionic acid group at the peptide’s C-terminus reacts with the free thiol group on cysteine-34 of serum albumin via a Michael addition reaction, forming a stable thioether bond. This conjugation is effectively irreversible under physiological conditions.
Once covalently attached to albumin, the peptide-albumin complex circulates with the kinetics of albumin itself — a protein that evades renal clearance (it is too large to be filtered) and is protected from lysosomal degradation by the neonatal Fc receptor (FcRn) recycling pathway. This confers CJC-1295 with DAC its remarkably extended half-life. Human pharmacokinetic data from ConjuChem’s Phase I and II studies reported mean half-lives of approximately 6 to 8 days, compared to the 7-minute half-life of native GHRH(1-44) in plasma. The extended action has both practical and mechanistic implications: a single weekly or biweekly injection can maintain elevated IGF-1 levels continuously, but at the cost of the sharp, rhythmic GH pulses that characterize normal physiology.
The albumin-bound peptide retains biological activity because CJC-1295 binds GHRH-R through its N-terminal domain, which remains sterically accessible even when the C-terminus is tethered to albumin. Gradually, slow hydrolysis of albumin in tissue compartments releases active peptide locally, contributing to tissue-level signaling beyond what circulating GH alone would explain.
The downstream consequences of CJC-1295-driven GH release are mediated largely through insulin-like growth factor 1 (IGF-1), synthesized primarily in the liver in response to GH receptor activation. GH binds its receptor (GHR) on hepatocytes, triggering JAK2 activation and STAT5b phosphorylation — the canonical JAK-STAT pathway that drives IGF-1 gene transcription. Circulating IGF-1 then acts on the IGF-1 receptor (IGF-1R), a receptor tyrosine kinase expressed in virtually every tissue.
IGF-1R activation stimulates the PI3K/Akt/mTOR pathway, promoting protein synthesis, cell growth, and survival. In skeletal muscle, this pathway activates satellite cells and promotes hypertrophy. In adipose tissue, IGF-1 and GH work in complementary but sometimes opposing directions — GH directly promotes lipolysis via hormone-sensitive lipase activation, while IGF-1 supports glucose uptake. The net body composition effect observed in studies — increased lean mass and decreased fat mass — reflects the integrated action of both hormones across multiple tissue compartments over weeks to months of elevated GH/IGF-1 signaling.
Research in rodent models has also demonstrated that elevated IGF-1 supports neural plasticity and neuroprotection, through activation of the same PI3K/Akt pathway in neurons, suggesting potential cognitive and neuroprotective dimensions to sustained GHRH analog administration that warrant further investigation.
The most directly relevant human clinical data for CJC-1295 comes from two Phase I/II trials conducted by ConjuChem and published in the mid-2000s. In a randomized, double-blind, placebo-controlled study published in the Journal of Clinical Endocrinology and Metabolism in 2006 by Ionescu and Frohman, healthy adults aged 21-61 received single or multiple doses of CJC-1295 with DAC. Mean GH concentrations increased by 2 to 10-fold above baseline, and IGF-1 levels rose by 1.5 to 3-fold, with effects maintained for 6 to 7 days after a single injection. Notably, GH and IGF-1 returned to baseline without rebound suppression, and the pulsatile nature of GH secretion was preserved — pulses increased in amplitude rather than disappearing into a flat plateau.
A subsequent multi-dose study found that with weekly or biweekly injections over 28 days, IGF-1 remained consistently elevated, suggesting no tachyphylaxis at these dosing intervals. These findings are significant because they suggest CJC-1295 with DAC could sustain the GH axis in a state of mild, continuous amplification without desensitizing pituitary receptors — a concern with many continuous GHRH infusion protocols. Body composition endpoints were not the primary focus of these early safety and PK trials, but the metabolic implications of sustained IGF-1 elevation have been explored extensively in GHRH analog literature using tesamorelin as a proxy, with consistent findings of visceral fat reduction and lean mass accrual in treated populations.
One of the more intriguing research angles for CJC-1295 without DAC is its potential to support sleep-associated GH secretion. Under normal physiology, the largest GH pulse of the day occurs 30 to 90 minutes after sleep onset, coinciding with slow-wave (stage 3-4) NREM sleep. This nocturnal pulse accounts for the majority of daily GH output in healthy adults. Research on GHRH administration during sleep has shown that exogenous GHRH infusion timed to sleep onset increases the amplitude of this pulse and simultaneously deepens slow-wave sleep, suggesting a bidirectional interaction: GH promotes slow-wave sleep, and slow-wave sleep facilitates GH release.
Studies by Marshall, Kerkhofs, and colleagues using IV GHRH infusion in human subjects demonstrated that GHRH administration significantly increased slow-wave sleep time, reduced intermittent waking, and improved subjective sleep quality. While these studies used intravenous native GHRH rather than CJC-1295 specifically, the mechanism of GHRH-R activation is identical. Animal studies using CJC-1295 without DAC administered subcutaneously prior to sleep have produced similar observations in rodent sleep EEG models, supporting the translational relevance of the finding. Researchers hypothesize that a short-acting GHRH analog administered before sleep could effectively amplify the natural nocturnal GH pulse without substantially altering daytime hormonal dynamics.
The anabolic dimension of CJC-1295 research has been examined in models of muscle repair and exercise adaptation. In a rat model of skeletal muscle injury, sustained elevation of IGF-1 via GHRH analog administration was associated with accelerated regeneration of damaged myofibers, increased satellite cell proliferation, and earlier recovery of contractile force compared to vehicle-treated controls. The mechanism involves IGF-1R-mediated Akt phosphorylation in satellite cells, which promotes their transition from quiescence to active proliferation and subsequent differentiation into new myofibers.
Additionally, GH’s direct effects on connective tissue — stimulating type I collagen synthesis and proteoglycan production in tendons and ligaments via IGF-1-dependent and -independent mechanisms — suggest a broader tissue repair role that extends beyond muscle. Research groups studying GH-deficient animal models have consistently found impaired wound and tendon healing that is reversed by GH or IGF-1 replacement, supporting the biological plausibility of using GHRH stimulation to accelerate musculoskeletal recovery. These findings remain in preclinical territory with respect to CJC-1295 specifically, but the upstream mechanism is well-characterized.
GH is a potent lipolytic hormone. It increases adipose tissue lipolysis primarily by stimulating hormone-sensitive lipase (HSL) activity and suppressing lipoprotein lipase (LPL), the enzyme responsible for clearing circulating triglycerides into fat cells. GHRH analog-driven GH elevation has consistently been shown in animal studies to reduce visceral fat depots preferentially over subcutaneous fat, a pattern that mirrors the effects of tesamorelin in HIV patients and of GH replacement in GH-deficient adults. Visceral adiposity is independently associated with metabolic syndrome, insulin resistance, and cardiovascular risk, making this effect potentially clinically meaningful.
In rodent studies specifically using long-acting GHRH analogs, 4 to 8 weeks of treatment produced significant reductions in visceral fat mass measured by DEXA and MRI without accompanying hyperglycemia at moderate doses — an important distinction from pharmacological GH administration, which can cause insulin resistance at high doses. At very high doses, GHRH analog-driven GH elevation does begin to impair insulin signaling through GH’s counter-regulatory effects on glucose metabolism, suggesting a therapeutic window that future clinical research will need to define carefully.
In the human pharmacokinetic studies conducted by ConjuChem, CJC-1295 with DAC was administered at doses ranging from 30 mcg/kg to 120 mcg/kg as single injections, with dose-dependent increases in both GH peak amplitude and IGF-1 AUC. The 60 mcg/kg and 90 mcg/kg doses produced the most consistent GH and IGF-1 responses with acceptable tolerability in healthy adults. For a 75 kg individual, this corresponds to approximately 4,500 to 6,750 mcg (4.5 to 6.75 mg) per injection — doses notably higher than those commonly used in research peptide community protocols, which typically range from 1,000 to 2,000 mcg (1-2 mg) per injection.
For CJC-1295 without DAC, animal studies and peptide pharmacology research suggest effective doses in the range of 100 to 300 mcg per injection in rodents (approximately 1 to 3 mg/kg), producing measurable acute GH pulses. When combined with a GHRP such as ipamorelin, the synergistic GH release observed in animal models allows effective doses of each compound to be reduced, as the two mechanisms amplify each other. Researchers using the peptide dosing calculator should note that body-weight-based dosing from animal studies does not translate linearly to human dosing due to allometric scaling differences.
Subcutaneous (SC) injection is the primary administration route studied for CJC-1295 in both animal models and the ConjuChem human trials. The subcutaneous route provides predictable absorption kinetics with slower entry into systemic circulation compared to intravenous injection, which is appropriate for a peptide whose DAC technology is designed to create a long-acting depot effect. Injection sites in research protocols are typically the abdomen, lateral thigh, or deltoid region.
Intramuscular (IM) injection has been used in some animal studies and produces faster peak plasma concentrations compared to SC injection, but this advantage is less meaningful for the long-acting DAC variant where the duration of action dominates the pharmacokinetic profile. For the no-DAC variant, IM injection may produce a slightly sharper GH pulse.
Intranasal and oral administration of CJC-1295 have not been meaningfully studied. Peptides in this molecular weight range (3,000+ Da) are poorly absorbed across nasal mucosa and are extensively degraded in the gastrointestinal tract, making these routes impractical without specialized delivery technology. IV administration was used in ConjuChem’s early dose-escalation studies but is not typical for ongoing research use.
For CJC-1295 with DAC, the extended half-life supports once-weekly or once-every-two-weeks dosing protocols based on the PK data from ConjuChem’s studies. The multi-dose human study used twice-monthly injections and maintained elevated IGF-1 throughout. Some researchers use once-weekly dosing to maintain more consistent IGF-1 elevation without accumulation concerns. Treatment durations in animal studies have ranged from 4 to 16 weeks; human studies examined 4-week windows. Long-term cycling (e.g., 12 weeks on, 4 weeks off) is a common approach in research protocols to allow the GH axis to reset, though this practice is based on pharmacological principle rather than direct long-term CJC-1295 data.
For CJC-1295 without DAC, more frequent dosing is required given the shorter half-life. Research protocols often use daily to three-times-weekly injections. When combined with ipamorelin, injections are typically timed to periods of low somatostatin tone — such as late evening before sleep or mid-morning between meals — to maximize GH pulse amplitude.
CJC-1295 supplied as a lyophilized (freeze-dried) powder is typically reconstituted with bacteriostatic water (BAC water, 0.9% benzyl alcohol in sterile water) rather than plain sterile water, as the benzyl alcohol preservative extends the usable life of the reconstituted solution. Standard practice uses 1 to 2 mL of BAC water per vial, with the water added slowly down the side of the vial to avoid agitating or denaturing the peptide. The vial should be gently swirled — not shaken — until the powder fully dissolves.
Lyophilized CJC-1295 should be stored at 4°C (refrigerated) and can remain stable for 24 months or longer under proper cold storage. Reconstituted solution should be refrigerated, protected from light, and used within 28 to 30 days of reconstitution. Exposure to temperatures above room temperature, repeated freeze-thaw cycles, or UV light can degrade the peptide. For further guidance on peptide handling, the AI research coach can address specific preparation questions.
Preclinical toxicology studies on CJC-1295 have not been published in full in the open literature, which is a genuine limitation of the available evidence base. In the animal pharmacology studies that do exist, CJC-1295 at research doses was generally well-tolerated, with no reports of acute organ toxicity or gross histopathological changes in treated animals at doses used to study GH and IGF-1 dynamics. The primary safety signals identified in animal models mirror those expected from GH excess: dose-dependent transient increases in blood glucose, mild water retention, and in some studies, transient injection-site reactions. No formal LD50 determination for CJC-1295 has been published in peer-reviewed literature as of 2025.
Long-term concern in animal models has centered on whether sustained GHRH receptor activation leads to pituitary somatotroph hyperplasia or adenoma formation. Chronic GHRH overexpression in transgenic mouse models does produce somatotroph hyperplasia, but this represents a pathological level of continuous stimulation. Intermittent dosing protocols in animal studies have not reproduced this finding, suggesting that cycling and appropriate dosing intervals may mitigate this theoretical risk.
In ConjuChem’s human studies, the most commonly reported adverse effects were transient injection-site reactions (redness, swelling, mild pain), flushing, and transient headache — findings consistent with other peptide injection research. Water retention (edema) was reported at higher doses, consistent with GH’s known anti-natriuretic effects. Transient hypoglycemia was not observed at the doses studied, but the counter-regulatory potential of GH elevation on insulin sensitivity is a pharmacological consideration worth noting, particularly for individuals with impaired glucose metabolism.
CJC-1295 with DAC’s interaction with the albumin pool is theoretically relevant: because it binds cysteine-34 of albumin — the same site used by many drugs and fatty acids — there is potential for displacement interactions with highly albumin-bound pharmaceuticals, though this has not been formally studied in combination regimens. Anyone managing existing medical conditions should discuss research compound use with a qualified healthcare provider.
The published human clinical data for CJC-1295 is limited to the ConjuChem Phase I/II trials, which were conducted in relatively small cohorts (fewer than 100 subjects total), over short durations (4 weeks), and focused on pharmacokinetics and safety rather than long-term efficacy endpoints. ConjuChem ultimately discontinued active clinical development of CJC-1295, which means the compound has not progressed to the larger Phase III trials that would generate robust safety and efficacy data. No peer-reviewed studies have examined CJC-1295 use over months to years in any population. The body composition, muscle recovery, and sleep benefits discussed in this article rest on a combination of direct CJC-1295 data (limited), tesamorelin and GHRH analog class-effect data, and mechanistic reasoning from GH/IGF-1 biology — not from long-term CJC-1295-specific clinical trials. This content is for research and informational purposes only and does not constitute medical advice.
The core molecular structure of both variants is identical: a 29-amino acid GHRH analog with stabilizing amino acid substitutions. The defining difference is the Drug Affinity Complex (DAC) linker present only in the long-acting version. CJC-1295 with DAC covalently binds to serum albumin in the bloodstream after injection, extending its half-life to 6 to 8 days and allowing once-weekly dosing. CJC-1295 without DAC — also called Modified GRF(1-29) — lacks this linker and has a half-life of roughly 30 minutes to a few hours, producing a discrete GH pulse more similar in timing to natural GHRH. Researchers choose between them based on whether they want pulsatile GH stimulation (no DAC) or sustained GH/IGF-1 elevation (with DAC). For dosing support, visit the peptide calculators page.
Direct GH injection bypasses the pituitary entirely, introducing exogenous GH that does not undergo the natural pulsatile pattern of secretion. This can suppress the pituitary’s own GH output through negative feedback and, at pharmacological doses, cause insulin resistance, fluid retention, and joint pain more readily than physiological stimulation. CJC-1295 works upstream, stimulating the pituitary to produce and release its own GH in a manner that remains subject to somatostatin feedback regulation. The result is amplified natural GH secretion rather than replacement, preserving some degree of axis responsiveness. IGF-1 elevation from CJC-1295 is generally more modest than from high-dose exogenous GH, which may translate to a different side effect profile, though direct comparative human data is lacking.
This is one of the most studied combinations in GHRH/GHRP research. CJC-1295 acts on the GHRH receptor on pituitary somatotrophs, while ipamorelin acts on the ghrelin/GHS-R receptor — a distinct receptor that independently triggers GH release and also suppresses somatostatin. Because the two compounds work through different but complementary receptor pathways, their effects on GH pulse amplitude are additive to synergistic. Animal studies have shown that co-administration produces substantially higher GH peaks than either compound alone at the same individual doses. The combination is most commonly studied with CJC-1295 without DAC, since the timing of ipamorelin administration can be matched to when GHRH-R activity is at its peak. The peptide database has additional entries on ipamorelin for reference.
This concern stems from IGF-1’s known role as a mitogenic signaling molecule — elevated IGF-1 in epidemiological studies has been associated with increased risk of certain cancers, particularly breast and colorectal. However, no direct causal link between CJC-1295 use and cancer development has been demonstrated in available animal or human studies. The concern is theoretical and mechanistic rather than empirically established for this compound specifically. Researchers with pre-existing malignancies or strong family histories of hormone-sensitive cancers are advised to approach any GH-axis-modulating compound with particular caution. The available human studies found no neoplastic events in treated subjects, but these were short-term trials with small sample sizes — not powered to detect rare adverse events.
In ConjuChem’s human PK studies, IGF-1 levels elevated by CJC-1295 with DAC returned to baseline within 28 days of the last injection in most subjects, following the half-life kinetics of the albumin-bound compound. There was no evidence of sustained suppression of endogenous GH secretion below baseline after washout — a meaningful finding that distinguishes CJC-1295 from exogenous GH, where post-treatment axis suppression can persist for weeks or months. For CJC-1295 without DAC, the shorter half-life means GH pulse stimulation ceases within hours of the last injection, and endogenous GH patterns resume without delay. This reversibility is considered one of the pharmacologically favorable characteristics of GHRH-based approaches compared to direct GH administration.
Research on GHRH biology suggests that injecting CJC-1295 without DAC at times of low somatostatin tone maximizes the resulting GH pulse. Somatostatin tone is naturally lower during early sleep onset and during the mid-to-late morning between meals. For sleep-associated GH optimization, research protocols often administer the compound 30 to 60 minutes before sleep, timed to coincide with the body’s naturally occurring peak GH release window. For daytime protocols, mid-morning or post-exercise windows (when GHRH receptor sensitivity recovers after the morning pulse) are often used. Meals, particularly carbohydrate-rich ones, increase insulin and can modulate somatostatin tone, which is why fasted-state injections are preferred in many research protocols. Have a specific timing question? The AI research coach can help.
The legal status of CJC-1295 varies significantly by jurisdiction. In the United States, it is not FDA-approved for any indication and is not scheduled as a controlled substance under the Controlled Substances Act, but it is illegal to sell for human consumption. It may be purchased legally as a research chemical for in vitro or laboratory research purposes. In Australia, it is listed as a Schedule 4 prohibited substance. The UK, Canada, and EU each have their own regulatory frameworks. Researchers should verify current regulations in their specific country before sourcing or handling the compound. This article is for informational and research purposes only.
Both compounds are GHRH(1-29) analogs with stabilizing modifications, and both act on the same GHRH receptor. Tesamorelin differs in its modification strategy: it uses a trans-3-hexenoic acid moiety at the N-terminus to improve stability without DAC technology, resulting in a half-life of approximately 26 to 38 minutes. Tesamorelin reached FDA approval (as Egrifta) in 2010 for reducing visceral fat in HIV-associated lipodystrophy, making it the most clinically validated GHRH analog available. CJC-1295 with DAC achieves vastly longer duration of action through albumin binding, a mechanistic difference that makes direct comparison difficult. The body composition effects in HIV lipodystrophy that tesamorelin demonstrated in Phase III trials provide the strongest clinical evidence base for the class, with CJC-1295 extrapolating from that foundation while adding its own unique pharmacokinetic profile.
Disclaimer: This information is for research and educational purposes only. It is not medical advice. Consult a qualified healthcare professional before using any peptide.