CJC-1295

Mechanism of action

CJC-1295 is a 30-amino-acid synthetic analogue derived from the biologically active N-terminal 1-29 fragment of human growth-hormone-releasing hormone (GHRH 1-29, sermorelin) through four amino-acid substitutions that confer resistance to enzymatic degradation: D-Ala at position 2 (protects against dipeptidyl peptidase-4, DPP-4, cleavage of the N-terminal His-Ala bond — the principal degradation pathway of native GHRH), Gln at position 8, Ala at position 15, and Leu at position 27. The first three substitutions extend the in-vivo half-life of the underlying GHRH sequence from approximately two minutes (native GHRH 1-44) to approximately 30 minutes (the no-DAC variant, identical to Modified GRF 1-29 or 'Mod GRF 1-29'). The DAC (drug affinity complex) variant adds a critical second-stage modification: a maleimide group covalently attached to the side chain of lysine 30 (a residue added beyond the native 1-29 sequence specifically for this purpose). On subcutaneous administration the maleimide forms a covalent thioether bond with the free cysteine-34 residue of circulating serum albumin, anchoring the peptide to a 67 kDa protein carrier with a half-life of ~19 days in humans. The albumin-bound CJC-1295 is shielded from renal filtration and protease degradation, extending the functional plasma half-life from minutes to 6–8 days while maintaining GHRH-receptor binding affinity. This is the principal pharmacological innovation of the DAC variant and the basis of the once- or twice-weekly dosing regimen explored in clinical-trial programmes. The pharmacological consequence of the half-life extension is critically dependent on dosing variant. The no-DAC form (~30-minute half-life) preserves the pulsatile pattern of native GHRH-driven GH release — each injection produces a transient GH pulse that mimics the physiological release pattern, with somatostatin tone restoring baseline between pulses. The DAC form produces sustained receptor occupancy with a tonic rather than pulsatile pattern; circulating GH and IGF-1 rise to a new steady-state plateau. Research evidence (Teichman et al., J Clin Endocrinol Metab, 2006) showed that DAC-modified CJC-1295 produced sustained 2- to 10-fold elevations in IGF-1 over 28 days at clinically relevant doses, with peak IGF-1 reached approximately one week after administration. The pulsatile-versus-sustained distinction has substantial mechanistic implications. Pulsatile GH release respects the physiological negative-feedback loops (IGF-1, somatostatin) and is the pattern under which IGF-1 sensitivity is preserved; sustained GH elevation desensitises target tissues, can drive IGF-1 receptor downregulation, and produces a different metabolic phenotype. Research programmes that use the no-DAC variant are typically pursuing the physiological-pulse pattern; programmes using the DAC variant are pursuing sustained-elevation pharmacology, accepting the trade-off in pulsatility for the convenience of weekly dosing. Downstream of GHRH-receptor activation on anterior-pituitary somatotrophs, CJC-1295 reproduces the canonical Gαs/adenylate cyclase/cAMP/PKA cascade of native GHRH, triggering GH gene transcription and pulsatile release of stored GH. Released GH binds the GH receptor on hepatocytes and peripheral tissues, activating JAK2/STAT5 signalling and driving IGF-1 production. Combined administration with a GHRP-class secretagogue such as ipamorelin produces synergistic GH pulses materially larger than either monotherapy — the foundation of the standard 'CJC-1295 + ipamorelin' research protocol.

The DAC variant produces sustained 2- to 10-fold IGF-1 elevation over 28 days after a single subcutaneous dose — a pharmacokinetic profile fundamentally distinct from the pulsatile pattern of native GHRH or the no-DAC variant, achieved through covalent albumin binding via the maleimide-modified lysine 30 side chain (Teichman et al., J Clin Endocrinol Metab, 2006).

— Notable finding

Research history

CJC-1295 was developed by ConjuChem (Montreal), a biopharmaceutical company specialising in albumin-binding therapeutic peptides through their proprietary Drug Affinity Complex (DAC) technology platform. The compound entered clinical development in the mid-2000s as a once-weekly growth-hormone-replacement candidate for indications including HIV-associated lipodystrophy, age-related sarcopenia, and adult growth-hormone deficiency. The DAC-modified variant was the original commercial development target; the no-DAC variant (Modified GRF 1-29) was a development intermediate that subsequently entered the research-chemical market independently. The key clinical study published by Teichman and colleagues (J Clin Endocrinol Metab, 2006) demonstrated that CJC-1295 (DAC variant) at subcutaneous doses of 30 µg/kg, 60 µg/kg, and 90 µg/kg in healthy adults produced sustained dose-dependent elevations in serum GH and IGF-1 across a 28-day observation period, with IGF-1 elevations of 1.5- to 3-fold above baseline lasting through the dosing interval. A subsequent Phase II programme in HIV-lipodystrophy showed similar IGF-1 elevation but did not advance to registration; ConjuChem's clinical development of the compound was discontinued, with no replacement sponsor pursuing FDA approval. The no-DAC variant (Mod GRF 1-29) had a separate development trajectory. As a sermorelin analogue without the albumin-binding modification, it was studied principally in academic settings and entered the research-chemical market through grey-market peptide suppliers in the late 2000s. Its use grew rapidly in athletic and anti-ageing communities for the appeal of mimicking endogenous GHRH-driven pulsatile GH release rather than producing sustained elevation. The combined 'CJC-1295 + ipamorelin' protocol — pairing the no-DAC GHRH analogue with the GHRP-class secretagogue ipamorelin to exploit dual-pathway synergy — became the dominant research-chemical-community protocol from approximately 2010 onwards. Neither variant holds marketing authorisation from any regulatory body. Both remain unlicensed substances in the UK and globally, available as research chemicals from non-pharmaceutical suppliers. The substantial commercial supply chain reflects sustained grey-market demand rather than regulatory development.

Reported research-model dose ranges

The ranges below are taken from published pre-clinical literature. They do not constitute a dosing recommendation for human use.

Summarised studies

Safety profile

Clinical-trial safety data for CJC-1295 derive principally from the Teichman 2006 publication and subsequent Phase II HIV-lipodystrophy work, providing a moderate-size human safety dataset for the DAC variant. The reported adverse-event profile was generally mild: injection-site reactions (erythema, pruritus, transient nodules) were the most common; mild flushing and brief somnolence following injection were reported; no clinically significant changes in routine haematology, biochemistry, or vital signs were observed at therapeutic dose ranges. No serious adverse events attributable to CJC-1295 itself were reported in the published trials. The principal theoretical concerns relate to chronic dosing — sustained GH/IGF-1 elevation rather than the peptide's acute effects. Chronic supraphysiological IGF-1 elevation theoretically carries oncogenic risk through IGF-1R activation on susceptible tissues, with epidemiological associations between elevated IGF-1 and several cancer types (prostate, breast, colorectal). The Teichman dataset showed IGF-1 elevations within the upper physiological range rather than supraphysiological, but extended chronic dosing data are absent. Insulin resistance is a well-documented complication of chronic GH/IGF-1 elevation, with fasting glucose and HOMA-IR shifting unfavourably during sustained GH replacement; pulsatile-pattern dosing (no-DAC variant or sermorelin-style protocols) mitigates this risk. The DAC variant's sustained receptor occupancy raises concerns specific to non-pulsatile GH delivery: GH receptor downregulation, loss of IGF-1 sensitivity over time, and the metabolic phenotype of chronic acromegaly-like exposure. These are theoretical rather than documented in the published trials, but they constitute the principal reason much research-community use favours the no-DAC variant despite its less convenient dosing. No serious immediate adverse events have been documented for either variant at research-protocol doses. Acute hypotension or anaphylaxis have not been reported. The peptide is sufficiently large (3,367 or 3,647 Da) that immunogenicity is theoretically possible with repeated dosing; mild ELISA-detectable anti-drug antibodies have been described in research-grade preparations but have not produced documented loss of efficacy. Sterility and endotoxin content of research-chemical-grade material remain the dominant practical safety variables, as with all injectable research peptides.

UK regulatory status

CJC-1295 (both DAC and no-DAC variants) is not authorised as a medicinal product by the UK Medicines and Healthcare products Regulatory Agency (MHRA) and holds no marketing authorisation in any jurisdiction. It is not a controlled substance under the Misuse of Drugs Act 1971. CJC-1295 is captured by the World Anti-Doping Agency (WADA) Prohibited List under category S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics) as a growth-hormone-releasing hormone analogue. Athletes subject to anti-doping testing should treat all GHRH-analogue and GHRP-class peptides as prohibited in-competition and out-of-competition regardless of claimed research purpose. WADA's approach to GH-axis peptides has hardened materially since approximately 2015 with the introduction of GH-isoform-ratio testing and IGF-1 elevation monitoring as detection tools alongside direct peptide identification. MHRA enforcement actions concerning CJC-1295 supply specifically have not been published in the public domain, but generic warnings on unlicensed peptide supply for human use apply. Research-grade CJC-1295 for legitimate in-vitro and animal research is available from research-chemical suppliers; possession for bona fide laboratory research is generally unrestricted in the UK. Supply or administration to humans outside an authorised clinical-trial framework engages the Human Medicines Regulations 2012 and is generally an offence. For animal research under ASPA (Animals (Scientific Procedures) Act 1986), CJC-1295 work in vertebrates requires Personal, Project, and Establishment Licences from the Home Office Drugs and Firearms Licensing Unit, and the work must pass a local Animal Welfare and Ethical Review Body assessment. The use of CJC-1295 in research animals does not automatically engage controlled-substance provisions but does require standard ASPA compliance.

Frequently asked questions