CJC-1295 vs MK-677: Research Comparison | Peptide Intel Hub

CJC-1295 is a truncated 30-residue GHRH analogue with four amino-acid substitutions that increase resistance to DPP-4 degradation. The 'with DAC' variant adds a maleimidopropionic-acid modification for covalent albumin binding and multi-day half-life; the 'no DAC' variant is the unmodified short GHRH analogue.

MK-677 (ibutamoren) is a non-peptide small molecule that acts as an orally active agonist at the growth-hormone-secretagogue receptor (ghrelin receptor / GHS-R1a). It drives GH release through the ghrelin axis rather than the GHRH axis, and is administered orally rather than by injection.

CJC-1295 is selective for the GHRH receptor. Downstream growth-hormone release follows the natural pulsatile pituitary pattern in research models, and the IGF-1 response follows the GH signal.

MK-677 is selective for the ghrelin receptor, engaging the same GHS-R axis as ipamorelin but with oral bioavailability and a substantially longer duration of action — sustained ghrelin-axis activation is characteristic of MK-677 in published research.

CJC-1295 no DAC has a short-to-medium half-life (daily research cadence). CJC-1295 with DAC has a multi-day half-life (weekly research cadence) driven by covalent albumin binding.

MK-677 has a reported half-life of approximately 24 hours and is dosed once daily orally in published research. The oral route and long duration make it a fundamentally different research tool from the injectable GHRH analogue.

CJC-1295 is used in GHRH-axis research, in growth-hormone secretagogue panels paired with ipamorelin, and in any research design requiring pulsatile GH release through the natural hypothalamic-pituitary axis.

MK-677 is used in research models requiring sustained ghrelin-axis activation, in oral-bioavailability research designs, and in longer-term chronic-exposure research where injection cadence is a design constraint.

Both CJC-1295 and MK-677 should only be sourced from suppliers that use independent third-party verification — Janoshik Analytical is the default verifier, with orthogonal independent laboratories used when batch chemistry calls for confirmation by a second method. Minimum release specification is ≥99.0% HPLC main-peak purity with matching mass-spectrometry molecular weight and water content within the published specification for the compound.

Batch COAs for both compounds should be published by the supplier so a researcher can audit the analytical detail. The /trust/how-to-read-a-coa reference walks through every field on a modern COA.

CJC-1295 ships lyophilised under nitrogen; hold at 2–8 °C, freeze at −20 °C for long-term storage, and reconstitute with bacteriostatic water. MK-677 ships as a solid or oral-solution research kit; storage conditions are cool and dry, protected from light. Both compounds support standard research-cadence handling.

Aliquot before any freeze. The single most common cause of measurable potency loss in research peptides is repeat freeze-thaw cycling — both CJC-1295 and MK-677 benefit from single-thaw aliquot workflows. Vortex gently, never shake aggressively, and keep reconstituted vials away from direct light. The /research/compound-storage-guide reference covers the per-compound stability windows in detail.

Researchers choose CJC-1295 when the protocol targets the GHRH receptor arm specifically or when pulsatile GH release is central to the experimental design. Researchers choose MK-677 when sustained oral ghrelin-axis activation is the experimental requirement — chronic-exposure metabolic, body-composition or sleep-architecture research models. Matched panels sometimes include both compounds in separate arms to isolate the axis contribution.

For multi-compound comparator studies, reputable suppliers can often reserve matched-batch inventory of both CJC-1295 and MK-677 against a project timeline so the experimental panel is sourced under a single analytical specification window.

CJC-1295 is characterized as a long-acting analog of growth hormone-releasing hormone (GHRH) (PMID 16352683). Its mechanism involves stimulating the production of growth hormone (GH) from the pituitary gland (PMID 30938069, PMID 19386527). This peptide incorporates a functional maleimido group at the C-terminus, which allows it to covalently bind to plasma proteins like serum albumin (PMID 30938069). These CJC-1295-protein conjugates exhibit a significantly extended half-life compared to the unconjugated peptide (PMID 30938069). Consequently, a single administration in humans can stimulate GH production for over six days (PMID 30938069). The administration of CJC-1295 has been shown to increase serum GH and insulin-like growth factor 1 (IGF-1) levels (PMID 19386527, PMID 16352683). In healthy adults, a single injection of CJC-1295 resulted in dose-dependent increases in mean plasma GH concentrations by 2- to 10-fold for 6 days or more, and in mean plasma IGF-I concentrations by 1.5- to 3-fold for 9-11 days (PMID 16352683). After multiple doses, mean IGF-I levels remained above baseline for up to 28 days (PMID 16352683). The estimated half-life of CJC-1295 was reported to be between 5.8 and 8.1 days (PMID 16352683). CJC-1295 is classified as a growth hormone-releasing hormone analogue (PMID 41880199).

Ibutamoren (MK-677), in contrast, is an orally active, nonpeptide growth hormone secretagogue (PMID 9467534, PMID 35716382, PMID 36354265). It stimulates GH release by binding to a pituitary and hypothalamic receptor, a mechanism distinct from the GHRH receptor (PMID 11452249). MK-677 is a potent, long-acting, selective non-peptide growth hormone secretagogue (PMID 35716382, PMID 34542924). In healthy volunteers undergoing caloric restriction, oral administration of MK-677 25 mg once daily for seven days significantly increased mean IGF-I concentration to 264 ± 31 ng/mL, compared to 188 ± 19 ng/mL with placebo (P < 0.01) (PMID 9467534). It also produced a peak GH response of 55.9 ± 31.7 micrograms/L after a single dose and 22.6 ± 9.3 micrograms/L after a week of dosing (PMID 9467534). In growth hormone-deficient children, short-term administration of ibutamoren mesylate (0.8 mg/kg per day for 8 days) increased serum GH peak concentration, GH area under the concentration-time curve, serum IGF-I, and serum IGF-binding protein 3 (IGFBP-3) (PMID 11452249). The ability of GHSs like ibutamoren to promote pulsatile release of GH, subject to negative feedback, may prevent supra-therapeutic levels of GH and their sequelae (PMID 28400207).

Human studies on CJC-1295 include randomized, placebo-controlled, double-blind trials conducted in healthy adults, aged 21-61 years (PMID 16352683). These studies examined pharmacokinetic profiles, pharmacodynamic effects, and safety (PMID 16352683). Doses were administered subcutaneously in ascending single doses or in multiple weekly/biweekly doses (PMID 16352683). The findings indicated sustained, dose-dependent increases in GH and IGF-I levels, suggesting potential utility as a therapeutic agent (PMID 16352683). There was also evidence of a cumulative effect after multiple doses (PMID 16352683). Another study analyzed serum from 11 healthy young adult men before and one week after CJC-1295 injection to identify proteomic changes, revealing alterations in an apolipoprotein A1 isoform, a transthyretin isoform, beta-hemoglobin, and fragments of albumin and immunoglobulin (PMID 19386527). A linear relationship was found between the spot containing immunoglobulin and albumin fragments and IGF-1 levels (PMID 19386527). Online forum activity has shown female use of CJC-1295 for weight loss, muscle enhancement, youthful skin, improved sleep, and injury healing, with users often experienced in poly-use of performance and image drug supplementation (PMID 26771670). Concerns were noted regarding female consequences of use due to gender variations in GH pulses affecting dosage and long-term consequences (PMID 26771670).

Ibutamoren (MK-677) has been investigated in human clinical trials for various conditions. A double-blind, randomized, placebo-controlled, two-period crossover study involving eight healthy volunteers (ages 24-39 years) found that oral MK-677 (25 mg daily) reversed diet-induced protein catabolism, improving nitrogen balance during caloric restriction (PMID 9467534). In a multicenter, randomized, placebo-controlled phase IIb study with 123 elderly hip fracture patients, 25 mg/day of MK-677 increased plasma IGF-1 levels by 51.4 ng/ml (PMID 21067829). However, this increase was not paralleled by improvement in most functional performance measures, although gait speed did increase (PMID 21067829). The MK-677 group experienced fewer falls (PMID 21067829). In growth hormone-deficient children, short-term oral administration of ibutamoren mesylate at 0.8 mg/kg per day for 8 days significantly increased serum GH peak concentration, GH AUC, serum IGF-I, and IGFBP-3 (PMID 11452249). Furthermore, chronic administration of MK-677 in elderly adults (65 years or older) increased serum IGF-I levels significantly (55-94%) and markers of bone turnover, including urinary N-telopeptide cross-links (NTXs), serum osteocalcin, and bone-specific alkaline phosphatase (BSAP) (PMID 10404019). The change in serum osteocalcin correlated with the change in serum IGF-I (PMID 10404019).

While primarily studied in humans, CJC-1295 has also been a subject in animal models. CJC-1295 combined with ipamorelin showed significantly improved maximum tetanic tension in murine models with glucocorticoid-induced muscle loss, though these findings are limited to animal studies (PMID 41476424). Equine plasma samples have been used to confirm CJC-1295 abuse, utilizing LC-MS/MS after immuno-affinity capture and tryptic digestion, with detection limits as low as 180 pg/mL in 1 mL of equine plasma (PMID 30938069). This demonstrates the peptide's presence and metabolic behavior in non-human physiological systems, providing insights relevant to detection in sports where its use is prohibited (PMID 34665524).

Ibutamoren (MK-677) has been extensively characterized in animal models, particularly for its metabolism and detection in competitive sports. In thoroughbred horses, oral administration of ibutamoren (MK-0677) led to the identification of 22 metabolites, including 17 phase I (hydroxylated, dissociated side chains, hydrogenated) and 5 phase II metabolites (glucuronic acid conjugates) (PMID 35716382). The major metabolites were detectable up to 96 hours after a single dose, and ibutamoren itself could persist for up to 72 hours (PMID 35716382). A separate study using equine liver microsomes detected 32 ibutamoren metabolites (20 phase I and 12 phase II), highlighting extensive oxidation and glucuronic acid conjugation (PMID 34542924). The presence of MK-0677 in equine hair was detected up to 209 days in mane and 358 days in tail after oral administration to a Thoroughbred racehorse (PMID 36354265). Wash procedures verified its internal incorporation (PMID 36354265). A case report described a 25-year-old male who ingested MK-677 (15 mg daily) along with LGD-4033 for 5 weeks. This co-administration impacted body composition, serum lipids, liver enzymes, and androgen-associated biomarkers (PMID 36303408).

CJC-1295 has generally shown a favorable safety profile in initial human adult trials. No serious adverse reactions were reported in healthy adults (PMID 16352683). It was found to be safe and relatively well tolerated, particularly at doses of 30 or 60 µg/kg (PMID 16352683). However, given its classification as an unapproved peptide and its presence in the

(PMID 41966639, PMID 42123471), concerns exist. Many unapproved peptides, including CJC-1295, lack rigorous human safety data despite promising preclinical results (PMID 41966639). The potential for serious harm to patients is noted (PMID 41966639). Therapeutic peptides, including CJC-1295, are part of the 'new era of doping' and are considered experimental substances with poorly defined long-term risks (PMID 41880199). Emerging data highlight potential risks such as cardiovascular strain, insulin resistance, dyslipidemia, and psychiatric instability associated with peptide use in sport (PMID 41880199).

Ibutamoren (MK-677) has a more prominent safety signal identified in human clinical trials. In the study involving elderly hip fracture patients, the trial was terminated early due to a safety signal of congestive heart failure in a limited number of patients (PMID 21067829). This led to the conclusion that MK-677 has an unfavorable safety profile in this patient population (PMID 21067829). While generally well tolerated in other contexts, there is concern for increases in blood glucose due to decreases in insulin sensitivity (PMID 28400207). Some peptides, including MK-677, have been associated with significant risks such as congestive heart failure and metabolic dysfunction like insulin resistance (PMID 42578445). The case report where a male ingested MK-677 for 5 weeks alongside LGD-4033 also noted negative impacts on bone, serum lipids (increased cholesterol, triglycerides, LDL-C; decreased HDL-C), liver enzymes (increased AST, ALT), and androgen-associated biomarkers (decreased free and total testosterone, SHBG) (PMID 36303408). Although these variables returned to pre-cycle values post-cycle, except for total fat mass (PMID 36303408), the transient negative impacts highlight potential risks associated with its use.

CJC-1295, along with other growth hormone-releasing hormone analogues, is a compound that has entered a 'gray market' operating largely outside regulatory oversight (PMID 41966639, PMID 42123471). While numerous peptide drugs undergo rigorous approval processes, CJC-1295 is frequently marketed direct to patients without such scrutiny (PMID 41966639). It is listed as an unapproved compound (PMID 41966639) and an investigational peptide that requires rigorous validation through well-designed clinical trials to establish safety and efficacy (PMID 42021992). The World Anti-Doping Agency (WADA) prohibits the administration of GHRH and its synthetic analogs, including CJC-1295, in sports (PMID 34665524). Detecting CJC-1295 in anti-doping samples has been challenging due to its low abundance, high molecular weight, and conjugation to various protein substrates, though methods for its confirmation in equine plasma by LC-MS/MS have been developed (PMID 30938069, PMID 34665524). The largely unregulated supply chain for such peptides exacerbates dangers, with products often mislabeled or contaminated (PMID 41880199). Its use in both competitive and recreational settings is considered high-risk and ethically problematic until longitudinal data clarify its safety and prevalence (PMID 41880199).

Ibutamoren (MK-677) also falls into the category of unapproved compounds that have gained popularity in the gray market for performance enhancement and accelerated recovery (PMID 42578445, PMID 41966639). It is a prohibited substance by the World Anti-Doping Agency (WADA) due to its potential for abuse as a performance-enhancing agent (PMID 35716382, PMID 36354265, PMID 42021992). Despite its growing popularity among patients and athletes, MK-677 often lacks efficacy or safety data, and is frequently perceived as low risk despite evidence to the contrary (PMID 42578445). The significant heterogeneity in dosing and route of administration for such emerging peptides further complicates their assessment (PMID 42578445). The absence of robust human safety data and the potential for serious harm to patients are significant concerns (PMID 41966639). The detection of MK-677 in hair samples provides a method for identifying its use, even after discontinuation (PMID 40882886, PMID 36354265), which is crucial for anti-doping efforts. The marketing claims for enhanced performance and accelerated recovery are largely unsubstantiated by current human trials (PMID 42578445).

Despite promising findings, the current evidence for many therapeutic peptides, including CJC-1295, is often insufficient for widespread clinical application, especially in orthopaedics and sports medicine (PMID 41476424). While preclinical studies are promising, there is a current lack of clinical trials (PMID 41490200). Many unapproved peptides demonstrate favorable tissue repair and metabolic outcomes in animal models, but rigorous human safety data are scarce (PMID 41966639). For CJC-1295, the human studies have focused on GH and IGF-I stimulation in healthy adults and some proteomic changes (PMID 16352683, PMID 19386527), but detailed long-term safety, efficacy, and specific therapeutic applications beyond GH modulation require further investigation (PMID 42021992). Specifically, evidence for orthopaedic applications, like the improved tetanic tension in murine models, is not yet validated in human trials (PMID 41476424). Significant knowledge gaps persist regarding optimal dosing regimens, combination therapy effects, and biomarkers for monitoring efficacy of investigational peptides like CJC-1295 (PMID 42021992). The clinical evidence supporting peptide use in sport is limited, with most published studies examining therapeutic applications under controlled dosing, not the supra-physiological or combined protocols common in bodybuilding (PMID 41880199).

For ibutamoren (MK-677), while some human trials exist, particularly in the context of hip fracture recovery and GH deficiency in children (PMID 21067829, PMID 11452249), the safety signals, particularly congestive heart failure, highlight the need for further rigorous evaluation (PMID 21067829, PMID 42578445). Long-term, rigorously controlled studies examining the efficacy and safety of growth hormone secretagogues like MK-677 are still few (PMID 28400207). More work is needed to understand the long-term impact on human anatomy and physiology across diverse clinical scenarios, and specifically, evaluation of cancer incidence and mortality with long-term use is required (PMID 28400207). The claimed benefits of emerging peptide supplements, including MK-677, for musculoskeletal recovery and performance remain unsubstantiated by current human trials (PMID 42578445). Human clinical studies were limited to a handful of investigations, most lacking robust controls or rigorous study designs (PMID 42578445). The full extent of peptide use in the general population is unknown, and prevalence studies are lacking, representing a critical gap in current knowledge (PMID 41880199).

Both CJC-1295 and ibutamoren (MK-677) modulate the growth hormone (GH) and insulin-like growth factor I (IGF-I) axis, but through distinct mechanisms and with different levels of evidence and safety considerations (PMID 16352683, PMID 9467534, PMID 28400207). CJC-1295, as a GHRH analog, directly stimulates pituitary GH production and exhibits a prolonged action due to its binding to plasma proteins, leading to sustained increases in GH and IGF-I in healthy adults (PMID 16352683, PMID 30938069). Its therapeutic potential is supported by its ability to maintain elevated IGF-I levels for extended periods (PMID 16352683). However, its primary clinical evidence remains centered on GH/IGF-I stimulation, and specific applications in areas like musculoskeletal repair are still largely in preclinical stages or lack robust human validation (PMID 41476424, PMID 41490200). The limited human safety data for long-term or widespread use, coupled with its status as an unapproved substance in a 'gray market,' necessitates caution and further rigorous study (PMID 41966639, PMID 41880199).

Ibutamoren (MK-677), an orally active ghrelin mimetic, also increases GH and IGF-I levels, and has shown promise in reversing diet-induced catabolism in healthy adults and increasing IGF-I in hip fracture patients and GH-deficient children (PMID 9467534, PMID 21067829, PMID 11452249). Its oral bioavailability is a distinguishing feature (PMID 9467534, PMID 35716382). However, the therapeutic potential of MK-677 is significantly overshadowed by safety concerns, notably a signal for congestive heart failure in elderly hip fracture patients and metabolic dysfunctions like insulin resistance (PMID 21067829, PMID 42578445). The lack of substantial human clinical trials supporting its efficacy for musculoskeletal recovery or performance enhancement, despite its popularity in the supplement market, underscores the gap between marketing claims and evidence-based medicine (PMID 42578445). Both peptides exemplify the broader challenge within therapeutic peptides: balancing promising mechanistic insights and preclinical data with the critical need for comprehensive human safety and efficacy trials before widespread adoption.

• 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. — The Journal of clinical endocrinology and metabolism (2006). PMID 16352683
• Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. — Journal of the American Academy of Orthopaedic Surgeons. Global research & reviews (2026). PMID 41490200
• Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. — Sports medicine (Auckland, N.Z.) (2026). PMID 41966639
• Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. — The American journal of sports medicine (2026). PMID 41476424
• Peptide Supplements and Their Therapeutic Applications in Sports Medicine. — The American journal of sports medicine (2026). PMID 42578445
• A method for confirming CJC-1295 abuse in equine plasma samples by LC-MS/MS. — Drug testing and analysis (2019). PMID 30938069
• Therapeutic peptides in gerontology: mechanisms and applications for healthy aging. — Frontiers in aging (2026). PMID 42021992
• Netnography of Female Use of the Synthetic Growth Hormone CJC-1295: Pulses and Potions. — Substance use & misuse (2016). PMID 26771670
• Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects. — Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society (2009). PMID 19386527
• Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives. — International journal of molecular sciences (2026). PMID 42123471
• A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: a critical review. — The Journal of sports medicine and physical fitness (2026). PMID 41880199
• Advances in the detection of growth hormone releasing hormone synthetic analogs. — Drug testing and analysis (2021). PMID 34665524
• MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. — The Journal of clinical endocrinology and metabolism (1998). PMID 9467534
• LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report. — Experimental physiology (2022). PMID 36303408
• Knowing the minimal detectable dose can facilitate the interpretation of a hair test result: II. Case example with ibutamoren (MK-677), a growth hormone secretagogue. — Clinica chimica acta; international journal of clinical chemistry (2026). PMID 40882886
• Characterization of growth hormone secretagogue small molecule ibutamoren (MK-0677) and its possible metabolites in thoroughbred horses for doping control. — Rapid communications in mass spectrometry : RCM (2022). PMID 35716382
• The Safety and Efficacy of Growth Hormone Secretagogues. — Sexual medicine reviews (2018). PMID 28400207
• MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture: a multicenter, randomized, placebo-controlled phase IIb study. — Archives of gerontology and geriatrics (2011). PMID 21067829
• Characterization of equine liver microsome-generated metabolites of growth hormone secretagogue small molecule ibutamoren. — Rapid communications in mass spectrometry : RCM (2021). PMID 34542924
• Oral administration of the growth hormone secretagogue MK-677 increases markers of bone turnover in healthy and functionally impaired elderly adults. The MK-677 Study Group. — Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (1999). PMID 10404019
• Effects of oral administration of ibutamoren mesylate, a nonpeptide growth hormone secretagogue, on the growth hormone-insulin-like growth factor I axis in growth hormone-deficient children. — Clinical pharmacology and therapeutics (2001). PMID 11452249
• Detection of the growth hormone secretagogue MK-0677 in equine hair following oral administration. — Drug testing and analysis (2023). PMID 36354265

Both CJC-1295 and MK-677 are supplied strictly for in-vitro and preclinical research use. They are not medicines, are not approved for human consumption in Spain, the United Kingdom, the European Union or the United States, and are not dispensed against a prescription. The research-use declaration ships with every package alongside the independent third-party COA.

Comparison pages on Peptide Intel Hub exist for laboratory-research reference. Nothing on this page constitutes a recommendation for human use of either compound.