If you have been reading about drug affinity complex and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
The drug affinity complex is a maleimidopropionic acid group attached to a lysine side chain. It reacts with the free thiol of cysteine-34 on circulating albumin, forming a covalent bond. This conjugation keeps the peptide in the bloodstream and shields it from rapid renal filtration and proteolysis. Reported circulation half-lives for the albumin-bound form fall in the range of roughly six to nine days in early human studies.
Binding to GHRH receptors on pituitary somatotroph cells triggers cyclic AMP signaling and stimulates growth hormone synthesis and release. Because the peptide acts upstream of the pituitary, effects are mediated through endogenous growth hormone rather than direct receptor activation in peripheral tissues. Increases in insulin-like growth factor 1 are generally described as a downstream consequence. Most published human exposure data come from small early-stage studies, and the clinical significance of the pharmacokinetic profile remains incompletely characterized.
CJC-1295 is a synthetic analogue of growth hormone-releasing hormone, built on the 29-amino-acid GHRH(1-29) fragment. Four substitutions distinguish it from the natural sequence: D-alanine at position 2, glutamine at position 8, alanine at position 15, and leucine at position 27. These changes reduce enzymatic cleavage and extend the peptide's persistence in circulation. The compound is discussed in two forms, one carrying a drug affinity complex and one without it.
Analytical confirmation usually relies on reversed-phase high-performance liquid chromatography for purity and on liquid chromatography coupled to mass spectrometry for identity. Mass data reveal the expected molecular mass and can flag truncated or oxidized species. Amino acid analysis and peptide mapping provide sequence-level verification. Immunoassays are used in some biological matrices, but antibodies raised against one releasing-hormone analog may cross-react with another. Reported purity figures depend heavily on the method used, so comparisons between suppliers require matching the analytical approach.
The two variants differ dramatically in how long they persist in circulation. The form lacking the albumin-binding group has a plasma half-life measured in tens of minutes, comparable to the natural hormone fragment. The version carrying the drug affinity complex binds albumin and shows a half-life of roughly six to eight days in human studies. That figure comes from small trials that tracked hormone levels over extended periods. The physiological consequences of sustained versus pulsatile stimulation are still debated and the literature does not settle the point.
| Property | Value | Notes |
|---|---|---|
| Physical form | Lyophilized white powder | Supplied as a freeze-dried solid for research use |
| Molecular weight | Approximately 3,647 Da (DAC form) | Lower for the variant lacking the albumin-binding moiety |
| Solubility | Soluble in water and aqueous buffer | Typically dissolved in sterile or bacteriostatic water |
| Typical storage temperature | −20 °C or below | Dry powder, desiccated and protected from light |
| Common analytical method | Reversed-phase HPLC with mass spectrometry | Used for purity estimation and identity confirmation |
Two principal forms appear in the literature and in research supply. One carries a drug affinity complex, a maleimide-based group that forms a covalent bond with circulating albumin. This linkage slows clearance and produces a long-lasting elevation of peptide levels. The other form lacks that group and is often labeled MOD GRF(1-29). It has a much shorter circulation time. Both variants retain the same core receptor-binding sequence. Reported half-lives differ substantially between the two.
At the pituitary, the peptide binds the growth hormone-releasing hormone receptor on somatotroph cells. Receptor activation raises intracellular cyclic AMP and triggers release of stored growth hormone. Somatostatin and other hypothalamic signals modulate this response. Negative feedback from insulin-like growth factor 1 also influences output. The same regulatory architecture operates with the native hormone. Whether the synthetic analog alters feedback dynamics over repeated exposure remains an open question. Most published receptor work uses cell models rather than intact human systems.
Four amino acid substitutions separate the modified backbone from the parent GRF(1-29) sequence. These changes reduce recognition by dipeptidyl peptidase IV and related proteases, extending the interval before degradation. Development work in this area sought longer-acting GHRH analogs for endocrine investigation. Published descriptions treat the substitution set as a defining property of the core sequence, while the albumin-binding linker is described separately as an optional addition to that same backbone.
CJC-1295 is a synthetic peptide analog of growth hormone-releasing hormone, constructed on the 29-amino-acid fragment designated GRF(1-29). The name began as an internal development code during the 1990s and later spread through research supply catalogs and discussion forums. The molecule does not occur in nature; its sequence is engineered rather than isolated from tissue. Two related compounds are sold under this single label, and they differ by one appended chemical group that strongly influences how long the peptide remains in circulation.
Downstream of growth hormone, the liver and other tissues increase production of insulin-like growth factor 1, a mediator of many growth-promoting effects. Studies have documented elevated levels of both hormones after dosing, and the rise from the long-acting form persists longer than that produced by shorter-acting analogues. What remains unclear is whether sustained elevation of these markers translates into meaningful clinical benefit, and whether prolonged exposure carries risks that short trials could not detect.
CJC-1295 acts at the growth hormone-releasing hormone receptor, a G-protein-coupled receptor found on somatotroph cells in the anterior pituitary. Binding triggers a rise in cyclic AMP and calcium entry, which promotes release of stored growth hormone. Because the peptide mimics the body's own releasing hormone, it amplifies existing secretory pulses rather than driving continuous output. The size of the response therefore depends partly on the subject's own hormonal rhythm and feedback state.
Two related peptides circulate under the CJC-1295 label, and they differ mainly in how long they persist in circulation. The version carrying a drug affinity complex includes a maleimidopropionic acid linker that forms a covalent bond with serum albumin. The other version, usually written as modified GRF(1-29) or tetrasubstituted GRF(1-29), lacks that linker and is cleared quickly. Mixing the two produces inconsistent readings of published half-life values, because the linker rather than the receptor-facing sequence drives most of the difference.
The core sequence keeps the receptor-binding region of GHRH while replacing four positions that are vulnerable to dipeptidyl peptidase-4 and other proteases. Substitutions at positions 2, 8, 15, and 27 raise metabolic stability relative to the natural hormone. The N-terminal residues remain essential for activity, so changes there generally lower potency. Molecular weight sits near 3368 daltons for the tetrasubstituted analog without the linker, while the albumin-binding form is heavier because of the added maleimide group.
CJC-1295 is a synthetic peptide modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. Its sequence corresponds to the first twenty-nine residues of human GHRH, with four substitutions that slow enzymatic breakdown. Early descriptions placed the compound in research on growth hormone deficiency and related conditions, and later literature groups it with the long-acting GHRH analogs. The name appears in both laboratory and popular fitness writing, where it sometimes labels chemically different peptides.
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==== Recombinant DNA ==== Biotechnology in the modern sense of genetic engineering began in the 1970s, with the invention of recombinant DNA techniques. Restriction enzymes were discovered and characterized in the late 1960s, following on the heels of the isolation, then duplication, then synthesis of viral genes. Beginning with the lab of Paul Berg in 1972 (aided by EcoRI from Herbert Boyer's lab, building on work with ligase by Arthur Kornberg's lab), molecular biologists put these pieces together to produce the first transgenic organisms. Soon after, others began using plasmid vectors and adding genes for antibiotic resistance, greatly increasing the reach of the recombinant techniques. Wary of the potential dangers (particularly the possibility of a prolific bacteria with a viral cancer-causing gene), the scientific community as well as a wide range of scientific outsiders reacted to these developments with both enthusiasm and fearful restraint. Prominent molecular biologists led by Berg suggested a temporary moratorium on recombinant DNA research until the dangers could be assessed and policies could be created. This moratorium was largely respected, until the participants in the 1975 Asilomar Conference on Recombinant DNA created policy recommendations and concluded that the technology could be used safely. Following Asilomar, new genetic engineering techniques and applications developed rapidly. DNA sequencing methods improved greatly (pioneered by Frederick Sanger and Walter Gilbert), as did oligonucleotide synthesis and transfection techniques.
Adverse effects have been documented from vitamin B6 dietary supplements, but never from food sources. Even though it is a water-soluble vitamin and is excreted in the urine, doses of pyridoxine in excess of the dietary upper limit (UL) over long periods cause painful and ultimately irreversible neurological problems. The primary symptoms are pain and numbness of the extremities. In severe cases, motor neuropathy may occur with "slowing of motor conduction velocities, prolonged F wave latencies, and prolonged sensory latencies in both lower extremities", causing difficulty in walking. Sensory neuropathy typically develops at doses of pyridoxine in excess of 1,000 mg per day. As noted above, in 2023 the European Food Safety Commission set an adult UL at 12 mg/day. While Australia has set an upper limit of 50 mg/day, the Therapeutic Goods Administration requires a label warning about peripheral neuropathy if the daily dose is predicted to exceed 10 mg/day.
=== Incidents === The 1981 Louisville sewer explosions, which destroyed over 13 mi (21 km) of sewer lines and streets in the Kentucky city, were caused by ignition of hexane vapors which had been illegally discharged from a soybean processing plant owned by Ralston-Purina. Hexane was attributed as the cause of an explosion that occurred in the National University of Río Cuarto, Argentina on 5 December 2007, due to a hexane spill near a heat-producing machine that exploded, producing a fire that killed one student and injured 24 more. Occupational hexane poisoning has occurred with Japanese sandal workers, Italian shoe workers, Taiwan press proofing workers, and others. Analysis of Taiwanese workers has shown occupational exposure to substances including n-hexane. In 2010–2011, Chinese workers manufacturing iPhones were reported to have suffered hexane poisoning.
A hormone can perform functions over a larger spatial and temporal scale than can a neurotransmitter, which often acts in micrometer-scale distances. Hormonal signals can travel virtually anywhere in the circulatory system, whereas neural signals are restricted to pre-existing nerve tracts. Assuming the travel distance is equivalent, neural signals can be transmitted much more quickly (in the range of milliseconds) than can hormonal signals (in the range of seconds, minutes, or hours). Neural signals can be sent at speeds up to 100 meters per second. Neural signalling is an all-or-nothing (digital) action, whereas hormonal signalling is an action that can be continuously variable as it is dependent upon hormone concentration. Neurohormones are a type of hormone that share a commonality with neurotransmitters. They are produced by endocrine cells that receive input from neurons, or neuroendocrine cells. Both classic hormones and neurohormones are secreted by endocrine tissue; however, neurohormones are the result of a combination between endocrine reflexes and neural reflexes, creating a neuroendocrine pathway. While endocrine pathways produce chemical signals in the form of hormones, the neuroendocrine pathway involves the electrical signals of neurons. In this pathway, the result of the electrical signal produced by a neuron is the release of a chemical, which is the neurohormone. Finally, like a classic hormone, the neurohormone is released into the bloodstream to reach its target.
Sources: en.wikipedia.org
In contrast to his father, Carl saw his mother as unreliable and inconsistent, which caused him to associate women more broadly as having an "innate unreliability" (Later, these early impressions were revised: "I have trusted men friends and been disappointed by them, and I have mistrusted women and was not disappointed."). Emilie was an eccentric and depressed woman; she spent considerable time in her bedroom, where she said spirits visited her at night. Though she was normal during the day, Jung recalled that at night, his mother became strange and mysterious. He said that one night, he saw a faintly luminous and indefinite figure coming from her room, with a head detached from the neck and floating in the air in front of the body. Jung had a better relationship with his father.
Baechu-kimchi (배추김치) spicy napa cabbage kimchi, made from whole cabbage leaves Baechu-geotjeori (배추겉절이) unfermented napa cabbage kimchi Bossam-kimchi (보쌈김치) wrapped kimchi Baek-kimchi (백김치) white kimchi, made without chili pepper Dongchimi (동치미) a non-spicy watery kimchi Nabak-kimchi (나박김치) a mildly spicy watery kimchi Chonggak-kimchi (총각김치) cubed chonggak "ponytail" radish, a popular spicy kimchi Kkakdugi (깍두기) spicy cubed Korean radish strongly-scented kimchi containing fermented shrimp Oi-sobagi (오이소박이) cucumber kimchi that can be stuffed with seafood and chili paste, and is a popular choice during the spring and summer seasons Pa-kimchi (파김치) spicy green onion kimchi Yeolmu-kimchi (열무김치) is also a popular choice during the spring and summer, and is made with yeolmu radishes, and does not necessarily have to be fermented. Gat-kimchi (갓김치), made with Indian mustard Yangbaechu-kimchi (양배추 김치) spicy cabbage kimchi, made from "headed" cabbage leaves (as opposed to napa cabbage) Kimchi from the northern parts of Korea tend to have less salt and red chili and usually do not include brined seafood for seasoning. Northern kimchi often has a watery consistency. Kimchi made in the southern parts of Korea, such as Jeolla Province and Gyeongsang Province, uses salt, chili peppers and myeolchijeot (멸치젓, brined anchovy allowed to ferment) or saeujeot (새우젓, brined shrimp allowed to ferment), myeolchiaekjeot (멸치액젓), anchovy fish sauce, kkanariaekjeot (까나리액젓), liquid anchovy jeot, similar to fish sauce used in Southeast Asia, but thicker.
== Regulation == Protein concentration, which in turn are affected by expression levels and degradation rates; Protein affinity for proteins or other binding ligands; Ligands concentrations (substrates, ions, etc.); Presence of other proteins, nucleic acids, and ions; Electric fields around proteins. Occurrence of covalent modifications;
MD-derived structure predictions can be tested through community-wide experiments in Critical Assessment of Protein Structure Prediction (CASP), although the method has historically had limited success in this area. Michael Levitt, who shared the Nobel Prize partly for the application of MD to proteins, wrote in 1999 that CASP participants usually did not use the method due to "... a central embarrassment of molecular mechanics, namely that energy minimization or molecular dynamics generally leads to a model that is less like the experimental structure". Improvements in computational resources permitting more and longer MD trajectories, combined with modern improvements in the quality of force field parameters, have yielded some improvements in both structure prediction and homology model refinement, without reaching the point of practical utility in these areas; many identify force field parameters as a key area for further development. MD simulation has been reported for pharmacophore development and drug design. For example, Pinto et al. implemented MD simulations of Bcl-xL complexes to calculate average positions of critical amino acids involved in ligand binding. Carlson et al. implemented molecular dynamics simulations to identify compounds that complement a receptor while causing minimal disruption to the conformation and flexibility of the active site. Snapshots of the protein at constant time intervals during the simulation were overlaid to identify conserved binding regions (conserved in at least three out of eleven frames) for pharmacophore development.
Sources: en.wikipedia.org
The two share the same 29-amino-acid backbone. CJC-1295 carries an additional albumin-binding moiety that markedly extends its residence time in circulation, while the form without that moiety clears faster. Literature sometimes applies the name loosely to either variant.
It has not been approved by major regulatory agencies for any therapeutic indication. Material sold under this name is typically distributed for laboratory research only. Clinical use is not supported by large controlled trials.
Early human studies of the albumin-binding form reported circulation half-lives on the order of several days. The value depends on assay method and study design. Estimates for the form without the binding moiety are considerably shorter.
The version carrying the affinity complex bears a maleimide group that binds serum albumin, which extends its circulation time to several days. The version without it lacks this group and clears within roughly half an hour. The two are chemically related but behave very differently once in the body.