What it is
CJC-1295 is a 30-amino-acid synthetic analog of human GHRH(1-29) engineered by ConjuChem Biotechnologies as a long-acting growth-hormone-releasing-hormone agonist (MW 3,647.95 Da, CAS 863288-34-0). The backbone carries four stabilizing substitutions over native GHRH — D-Ala² (DPP-IV resistance), Gln⁸, Ala¹⁵, and Leu²⁷ (oxidation resistance) — and appends a C-terminal Lys³⁰ bearing an Nε-maleimidopropionyl group. That maleimide forms an irreversible thioether with the free Cys34 thiol of circulating serum albumin via Michael addition, converting the peptide into a ~70 kDa albumin conjugate that resists renal clearance and tracks albumin's 19–20 day half-life. The biological half-life observed in Teichman 2006 was 5.8–8.1 days, enabling once-weekly subcutaneous administration — a >10,000-fold plasma-persistence increase over native GHRH. The base backbone without the DAC maleimide (Modified GRF 1-29, sometimes called 'CJC-1295 without DAC') has a half-life of ~30 minutes and is a distinct research chemical with a different pharmacodynamic profile; the two should not be treated interchangeably.
In plain English
CJC-1295 is a lab-made copy of a natural hormone called GHRH (growth hormone-releasing hormone). The company ConjuChem tweaked it in four spots so enzymes in the body can't break it down as fast, and added a chemical hook on one end. That hook latches permanently onto albumin — the most common protein in your blood — which makes the whole thing too big for the kidneys to filter out. Because it rides on albumin, the drug stays active for 5 to 8 days instead of the 30 minutes native GHRH lasts. That's why it can be injected once a week. Important note: the version without the hook (called "Modified GRF 1-29" or "CJC-1295 without DAC") lasts only about 30 minutes and works very differently. Don't treat the two as the same drug.
How it works
- 01
GHRH-R agonism at pituitary somatotrophs
CJC-1295 binds the extracellular domain of the growth-hormone-releasing-hormone receptor (GHRH-R, GRF-R), a class B1 Gαs-coupled GPCR expressed predominantly on somatotrophs of the anterior pituitary. Receptor activation stimulates adenylyl cyclase, elevates intracellular cAMP, activates PKA, phosphorylates CREB, and drives transcription of the GH1 gene — the canonical GHRH signaling cascade. Receptor affinity is comparable to native GHRH; selectivity for GHRH-R over the GHS-R1a (ghrelin receptor) is preserved, which is why CJC-1295 does not meaningfully raise cortisol, prolactin, or aldosterone the way older non-selective secretagogues do (Teichman 2006).
In plain English
It presses the pituitary's "release growth hormone" button
CJC-1295 fits into the same "receiver" on pituitary cells that the body's own GHRH uses. When it binds, the cell kicks off a chain of signals that tells the pituitary to release growth hormone (GH) into the blood. It doesn't hit other similar receivers (the ones that control stress hormone, prolactin, or salt balance), which is why it doesn't mess with those like older, messier drugs do.
- 02
Albumin conjugation via maleimide-Cys34 chemistry
The Nε-maleimidopropionyl group on Lys³⁰ undergoes Michael addition with the free sulfhydryl of Cys34 on human serum albumin, forming a stable thioether bond. The resulting covalent albumin conjugate is too large for glomerular filtration (>60 kDa) and is protected from circulating peptidases. This is the same albumin-binding strategy later deployed in other long-acting peptide therapeutics and is the engineering feature that differentiates CJC-1295 DAC from its short-acting parent backbone, Modified GRF 1-29 (Teichman 2006; described in the ConjuChem patent literature reviewed in the Wikipedia CJC-1295 entry, 2026).
In plain English
It permanently attaches itself to a blood protein
CJC-1295 has a tiny chemical hook on one end. That hook grabs onto a specific spot on albumin — the most common protein in your blood — and forms a permanent bond. Once stuck together, the combo is too big for your kidneys to filter out and too protected for enzymes to chew up. That's the whole reason it lasts almost a week instead of minutes.
- 03
Sustained (tonic) vs pulsatile GH exposure
Native GHRH drives pulsatile GH secretion every 3–4 hours, modulated by somatostatin and IGF-1 negative feedback. CJC-1295 DAC replaces that pattern with a sustained, tonic elevation of GH over 6+ days per injection (Teichman 2006: 2–10× mean GH over 6+ days at 30–90 μg/kg). Whether chronic tonic elevation produces the same downstream phenotype as pulsatile elevation is an open question — pulsatile GH is more effective at some transcriptional targets (e.g., sexually dimorphic hepatic gene expression in rodents), and the clinical consequences of the substitution in humans are not characterized.
In plain English
It replaces normal GH pulses with a steady flow
Normally, your body releases GH in quick bursts every 3 to 4 hours. CJC-1295 replaces those bursts with a steady, elevated level that lasts 6+ days after each shot. Whether a steady flow does the same good things as the natural pulse pattern is an open question. Some body systems (at least in rodents) only respond to the pulses, not a flat level. What this means for people over the long term is not known.
- 04
Downstream GH/IGF-1 axis activation
GH released from somatotrophs drives hepatic IGF-1 production, which mediates most of the anabolic and metabolic downstream effects attributed to the axis: adipocyte lipolysis, hepatic gluconeogenesis, skeletal-muscle amino-acid uptake and protein synthesis via PI3K/Akt/mTOR, and chondrocyte proliferation. Teichman 2006 documented a 1.5- to 3-fold rise in IGF-1 for 9–11 days per dose, with cumulative elevation persisting up to 28 days on a repeat-dose schedule. Somatostatin and IGF-1 negative feedback remain intact, which is part of the theoretical safety argument for the compound.
In plain English
More GH means more IGF-1, which drives muscle and fat effects
When GH goes up, your liver makes more of a hormone called IGF-1, which is what actually drives most of the downstream effects — fat-burning, muscle protein-building, and cartilage growth. The 2006 trial saw IGF-1 rise 1.5 to 3 times above normal for 9 to 11 days per shot, stacking up to 28 days with repeat dosing. The body's own off-switches (other hormones that lower GH when IGF-1 gets too high) still work, which is part of the argument that CJC-1295 is safer than giving GH directly.
- 05
Trophic effects on somatotrophs
In GHRH-knockout mice, Modzsergi 2006 (Am J Physiol Endocrinol Metab) showed that daily CJC-1295 from 1 week of age for 5 weeks normalized body weight and length, increased total pituitary RNA and GH mRNA, and drove somatotroph proliferation on immunohistochemistry. Dosing every 48 or 72 hours was less effective, suggesting the trophic response depends on dose-frequency as well as exposure. This is the preclinical basis for the claim that CJC-1295 can restore functional pituitary output in states of upstream GHRH deficiency — it is not evidence for efficacy in adults with an intact GHRH axis.
In plain English
In animals missing natural GHRH, it grows the pituitary back
In mice genetically engineered to have no natural GHRH, daily CJC-1295 starting at one week old brought their body size back to normal and made their pituitary glands grow more GH-making cells. Dosing every 2 or 3 days worked less well. This shows it can rebuild function in animals missing the natural signal — but it does NOT prove anything about healthy adults who already have a normal system.
- 06
cAMP-driven DNA damage — the somatotroph proliferation caveat
Chesnokova 2019 (Endocrinology) documented dose-dependent DNA damage in pituitary somatotrophs under sustained GHRH-R/cAMP stimulation, both ex vivo and in vivo. The mechanism is consistent with the observation that GHRH-overexpressing transgenic mice develop somatotroph adenomas. This does not demonstrate that therapeutic CJC-1295 dosing causes pituitary tumors — but it is the most concrete mechanistic reason to be cautious about chronic tonic GHRH-R stimulation, and it has not been tested in humans.
In plain English
The safety catch: non-stop signaling can damage cell DNA
A 2019 study found that when pituitary GH-making cells get pushed non-stop (the way CJC-1295 pushes them), their DNA gets damaged in a dose-related way. This fits with a known finding: mice that genetically overproduce GHRH develop pituitary tumors. This doesn't prove that people taking CJC-1295 will get tumors — but it's the most specific safety warning we have, and it's never been tested in humans.
- 07
What is NOT known about the mechanism
Whether sustained-exposure GH (tonic) produces the same downstream clinical effects as pulsatile GH at equivalent AUC is not settled. Human pharmacokinetics of the albumin conjugate beyond the Teichman 2006 dataset are thin — tissue distribution, free vs albumin-bound fraction under disease states (hypoalbuminemia, inflammation), and drug-drug interactions with other albumin-binding drugs have not been characterized. The relationship between chronic IGF-1 elevation and long-term oncologic risk (particularly given the Chesnokova 2019 somatotroph signal) is untested in this specific compound.
In plain English
What we still don't know
We don't know if a steady-flow GH exposure does the same good work as the body's pulse pattern, even at the same total amount. Beyond the 2006 trial, there's very little human data on how it moves through the body — especially in people with low albumin (from liver disease, kidney problems, or inflammation), or how it interacts with other drugs that also ride on albumin. And the long-term cancer risk from keeping IGF-1 elevated — especially given the 2019 pituitary DNA-damage warning — has never been tested for this specific drug.