# CJC-1295: the long-acting door at GHRHR > CJC-1295 at the GHRH receptor — Growth Hormone Axis research peptides — CJC-1295 mapped precisely: a tetrasubstituted GHRH(1-29) analog with an albumin handle, its measured half-life, its effect on GH pulsatility and IGF-1, and the DAC/no-DAC split. Growth Hormone Axis research peptides, cited and dose-free. **01 / GHRH-receptor agonist** Four substitutions for protease resistance, one covalent bond to albumin, and a plasma residence measured in days rather than minutes — without, in the published record, flattening the pulse. ## Start here Natural growth-hormone-releasing hormone, or GHRH, is the body's own "release now" message to the pituitary. Enzymes in the blood take it apart almost as fast as it arrives, which is exactly what a signal meant to come in bursts should do. CJC-1295 is a laboratory redesign of the working end of that message. Chemists kept the first twenty-nine building blocks, swapped four of them for versions that enzymes cannot easily cut [7], and then — in one of the two versions sold — attached a chemical hook that latches onto albumin, the most abundant protein in blood. Riding on albumin, the peptide stops being cleared in minutes and instead circulates for days. Two consequences follow, and both matter more than any marketing claim. The signal lasts far longer than the natural one. And the two versions of CJC-1295, with and without that hook, behave so differently that treating them as one compound makes any duration figure meaningless. ## What it is CJC-1295 is a synthetic analog of human growth-hormone-releasing factor built on hGRF(1-29), the amino-terminal fragment of the native 44-residue hormone. It carries four amino-acid substitutions — D-alanine at position 2, glutamine at 8, alanine at 15 and leucine at 27 — that stabilise the alpha-helix and block cleavage by dipeptidyl peptidase IV as well as deamidation and oxidation [7]. From that shared scaffold the market sells two distinct drugs: - **CJC-1295 with DAC**, the "Drug Affinity Complex" form. A C-terminal lysine is functionalised with a maleimidopropionyl linker, which undergoes Michael addition with the free thiol on Cys34 of circulating serum albumin. The result is a covalent peptide-albumin conjugate whose clearance approaches that of albumin itself [7]. - **CJC-1295 without DAC**, sold as Modified GRF (1-29) or Mod GRF 1-29. It keeps all four substitutions but lacks the albumin-binding moiety, and is therefore short-acting. The compound has no approved human indication in any jurisdiction and is supplied for laboratory research use only. Its identity in gray-market supply is not hypothetical: high-resolution LC-MS/MS structurally identified CJC-1295 as the active ingredient of an unlabelled "GHRH" preparation seized in an anti-doping context [2], which is also the reason validated detection methods exist. ## How it works CJC-1295 binds the growth-hormone-releasing hormone receptor (GHRHR) on anterior-pituitary somatotrophs and activates Gs/cAMP/PKA signalling, stimulating both synthesis and pulsatile release of growth hormone; hepatic IGF-1 rises downstream. The current class review in *Nature Reviews Endocrinology* sets out this receptor signalling and the design rationale for long-acting analogs across the whole GHRH family, CJC-1295, sermorelin and tesamorelin (Egrifta) included [1]. The design question the molecule was built to answer was whether a GHRH signal could be made to persist without collapsing the pulse it exists to generate. The animal work that produced it screened a series of hGRF(1-29) analogs bearing a C-terminal maleimidopropionyl-lysine handle; the lead candidate showed a four-fold increase in GH area-under-the-curve over two hours compared with unconjugated hGRF(1-29) in rats, remained detectable in plasma beyond 72 hours, and was markedly more stable against dipeptidyl peptidase IV in vitro [7]. A long plasma residence is not the same thing as a long biological effect, and the knockout work makes the distinction concrete. In GHRH-knockout mice, 2 micrograms of CJC-1295 administered once every 24 hours fully normalised body weight and length, whereas 48- and 72-hour intervals were progressively less effective; pituitary GH messenger RNA rose under treatment [6]. Days of measurable peptide in plasma did not translate into days of equivalent axis output. ## What the research shows The human evidence base is small, early and pharmacological. No efficacy trial in healthy adults exists. **Duration and magnitude.** In healthy adults, single subcutaneous doses of 30 or 60 micrograms per kilogram produced dose-dependent 2- to 10-fold increases in mean plasma GH lasting six days or more, and 1.5- to 3-fold increases in IGF-1 lasting nine to eleven days. After multiple administrations IGF-1 remained above baseline for as long as 28 days, and the estimated half-life of CJC-1295 was 5.8 to 8.1 days [4]. Those are the numbers behind every "lasts a week" claim made for the DAC form, and they were measured in a pharmacokinetic study, not an outcome trial. **Pulsatility survives.** In healthy men aged 20 to 40, a single subcutaneous dose of 60 or 90 micrograms per kilogram raised trough or basal GH approximately 7.5-fold and increased mean GH by about 46% and IGF-1 by about 45% one week later — while the frequency and magnitude of pulsatile GH secretion were unaltered [5]. This is the central mechanistic result for the compound: continuous stimulation at GHRHR did not convert a pulsatile axis into a flat one. **A biomarker signature.** In 11 healthy young adult men, CJC-1295 shifted the serum proteome, decreasing apolipoprotein A1 and a transthyretin isoform while increasing a C-terminal albumin fragment and immunoglobulin and beta-hemoglobin species; the immunoglobulin and albumin-fragment signal correlated linearly with IGF-1 [3]. The practical value of that study is detection and confirmation of axis activation rather than any clinical endpoint. **What is absent.** There is no controlled trial of CJC-1295 for body composition, recovery, sleep or aging in healthy adults, at any duration. The original long-acting development programme was discontinued, and a patient death from the development era is frequently cited alongside the halted Phase 2 trial in HIV-associated visceral obesity; the public record does not establish that CJC-1295 caused it. The correct reading is unresolved history plus a programme that never reached approval. ## Reported effects, cautions and safety What follows in this first paragraph is anecdotal, not clinical evidence: it is a summary of what people in research-use communities say they experience, gathered from forums, clinic write-ups and consumer guides, with no verification of the material used, no controls and no measurement. Deeper and more restful sleep is the single most commonly reported effect and is often described as the first thing noticed, which at least rhymes with the biology, since GH release is concentrated in deep sleep. Faster recovery between training sessions, gradual fat loss described as showing up over weeks rather than days, a leaner look, and occasional reports of more daytime energy, sharper focus and firmer skin make up the rest of the benefit side. On the adverse side, water retention, bloating and puffiness are very commonly reported; tingling or numbness in the hands and injection-site reactions are frequent; flushing or a warm head-rush shortly after administration, drowsiness, headache, increased appetite and higher blood sugar are reported occasionally. None of it is a measured outcome, and no quantities are reported on this site. The documented cautions are separate from that, and they are grounded in mechanism, regulation and the published record: - **No approval anywhere.** CJC-1295 has never been approved for people by the FDA or any major regulator. The human evidence is a handful of early pharmacology studies [4][5]; nothing establishes long-term safety. - **Sustained IGF-1 elevation.** IGF-1 is mitogenic, and epidemiologic work has linked higher circulating IGF-1 to a modestly increased risk of certain cancers. Because the DAC form holds IGF-1 up for days at a time [4], the mechanism-based concern applies with particular force to anyone with a personal or family history of cancer. The link is a population association, not evidence that this compound causes cancer. - **Fluid retention and nerve compression.** GH promotes renal sodium and water retention, expanding fluid volume — the most plausible explanation for the commonly reported puffiness and carpal-tunnel-like tingling, and a genuine concern rather than a cosmetic one for anyone prone to edema, hypertension or cardiac strain. - **Glucose handling.** GH is glucose-sparing, so sustained axis stimulation can reduce insulin sensitivity and raise blood sugar. Studies of GHRH analogs have documented effects on insulin sensitivity, and prolonged stimulation is the exposure pattern most likely to matter. - **Immunogenicity, flagged by the regulator.** FDA briefing materials for the 2024 Pharmacy Compounding Advisory Committee cited immunogenicity and other safety concerns among the grounds for not recommending CJC-1295 for the Section 503A compounding bulks list. Long-acting albumin-binding designs carry such considerations by construction [1]. - **Form confusion is a safety issue.** Because the DAC form's duration is measured in days and the no-DAC form's in minutes to hours [4], not knowing which is in hand makes any reported effect uninterpretable and any exposure estimate wrong. - **Prohibited in sport at all times** under Section S2 of the WADA Prohibited List, with established detection assays [2]. ## Where it sits on the map CJC-1295 occupies the long-duration corner of the GHRH-receptor position. It shares a receptor and a signalling cascade with sermorelin and differs from it almost entirely in pharmacokinetics: same door, held open far longer. It shares nothing mechanistically with ipamorelin except the target cell, which is precisely why the two are discussed together. And it has no mechanistic overlap at all with MOTS-c. The honest summary of its position: the best-characterised molecule on this desk in terms of what it does to the axis in humans, and one of the least-characterised in terms of what that does to a person over time. --- Precision Peptide Planner charts where four growth-hormone-axis compounds bind and what the studies actually measured — a receptor map drawn from the literature, not a clinic, not a supplier, and not a protocol anyone can follow.