A practical reference on half-life: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-01-26. Anything still debated is marked as such rather than presented as settled.
CJC-1295 belongs to a class of synthetic peptides modeled on growth hormone releasing hormone, a forty-four amino acid signal produced by the hypothalamus. The compound is built from the first twenty-nine residues of the natural sequence, with four substitutions introduced at positions 2, 8, 15 and 27. These changes were designed to slow enzymatic breakdown while preserving receptor activation. The result is a peptide that is shorter than native GHRH and considerably more resistant to ordinary clearance pathways in circulation.
Two related forms appear under the CJC-1295 name. The simpler analogue, commonly written as modified GRF(1-29), carries the four substitutions but no additional conjugation. The second form attaches a maleimidopropionic acid linker to a lysine residue, a modification frequently called the drug affinity complex. That linker reacts with the free thiol on serum albumin to form a covalent bond. Because albumin has a long residence time in blood, the conjugated peptide stays in circulation far longer than the unconjugated analogue.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic GHRH analogue | Built on a 29 residue sequence |
| Primary target | GHRH receptor (GHRHR) | Class B G protein coupled receptor |
| Unconjugated half life | Minutes | Limited by protease degradation |
| Key modification | Four residue substitutions | Positions 2, 8, 15 and 27 |
| Common synonym | Modified GRF(1-29) | Usually denotes the form without DAC |
Binding of the peptide to the growth hormone-releasing hormone receptor on pituitary somatotrophs triggers a G protein coupled cascade that raises cyclic AMP and opens calcium channels. The result is greater secretion of growth hormone into the bloodstream. Because the peptide acts at the same receptor as the natural hypothalamic hormone, its effect is amplified pulse size rather than an entirely separate release pathway. Receptor binding alone does not determine the response, since somatostatin tone and other inputs modulate the final output.
The albumin-binding version stays in circulation for days, because covalent attachment to serum albumin shields the peptide from rapid filtration and degradation. Reported half-lives for this form fall in the range of several days. The version without the linker is cleared in minutes, with estimates often near thirty minutes in animal work. These figures come from small studies and vary with assay method, species, and route, so they are best read as approximate rather than fixed constants.
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.
The attached maleimide group explains the unusual duration of the DAC version. After injection it reacts with the thiol of cysteine-34 on serum albumin, forming a stable covalent bond. The resulting conjugate is too large for rapid kidney filtration and is shielded from many peptidases. Reported half-lives for this form reach several days, whereas the version without the group is cleared in roughly half an hour. That gap is the main pharmacological difference between the two.
Two related forms circulate in technical discussion under the same family name. The original version carries a drug affinity complex (DAC) that binds covalently to serum albumin after administration, and this linkage substantially extends circulation time. A second form, frequently written as modified GRF(1-29) or CJC-1295 without DAC, lacks that linker and clears much faster. The naming is a frequent source of confusion because the shorthand CJC-1295 can refer to either form depending on the source. Reports sometimes fail to specify which variant was studied.
The peptide backbone includes a D-alanine at position two, which resists cleavage by dipeptidyl peptidase IV, and several other substitutions that reduce degradation. Its molecular weight is roughly 3.4 kDa without the linker and about 3.6 kDa with it. The molecule is water soluble and is normally supplied as a lyophilized powder. Precise sequence and mass values depend on which variant is described, so technical documents usually state the exact form being referenced.
The body or shaft of the penis is the free portion of the human penis that is located outside of the pelvic cavity. It is the suspended middle portion of the organ, continuous proximally with the internal root and distally with the glans. Unlike the root, the body contains no muscle, consisting mostly of the corpora cavernosa, the corpus spongiosum and the spongy urethra, together with supporting skin, connective tissue, blood and lymphatic vessels and fascia. The corpora cavernosa are intimately bound to one another with a dorsally fenestrated septum, which becomes a complete one before the penile crura. The body of the penis is homologous to the female clitoral body.
== Further reading == Ellington, W Ross (2001). "Evolution and Physiological Roles of Phosphagen Systems". Annual Review of Physiology. 63 (1): 289–325. doi:10.1146/annurev.physiol.63.1.289. PMID 11181958. Eggleton, Philip; Eggleton, Grace Palmer (1927). "The physiological significance of "phosphagen"". Journal of Physiology. 63 (2): 155–161. doi:10.1113/jphysiol.1927.sp002391. PMC 1514923. PMID 16993876. Eggleton, Philip; Eggleton, Grace Palmer (1928). "Further observations on phosphagen". Journal of Physiology. 65 (1): 15–24. doi:10.1113/jphysiol.1928.sp002457. PMC 1515019. PMID 16993934. Baldwin, Ernest (1933). "PHOSPHAGEN". Biological Reviews. 8 (1): 74–105. doi:10.1111/j.1469-185X.1933.tb01088.x. ISSN 1464-7931. S2CID 221532329.
This principle of self-determination had been declared on numerous occasions subsequent to the declaration – President Wilson's January 1918 Fourteen Points, Sykes's Declaration to the Seven in June 1918, the November 1918 Anglo-French Declaration, and the June 1919 Covenant of the League of Nations that had established the mandate system. In an August 1919 memo Balfour acknowledged the inconsistency among these statements, and further explained that the British had no intention of consulting the existing population of Palestine. The results of the ongoing American King–Crane Commission of Enquiry consultation of the local population – from which the British had withdrawn – were suppressed for three years until the report was leaked in 1922. Subsequent British governments have acknowledged this deficiency, in particular the 1939 committee led by the Lord Chancellor, Frederic Maugham, which concluded that the government had not been "free to dispose of Palestine without regard for the wishes and interests of the inhabitants of Palestine", and the April 2017 statement by British Foreign Office minister of state Baroness Anelay that the government acknowledged that "the Declaration should have called for the protection of political rights of the non-Jewish communities in Palestine, particularly their right to self-determination."
Sources: en.wikipedia.org
== Other roles == Thy-1 knock out mice also show impaired cutaneous immune responses and abnormal retinal development: thinning of the inner nuclear, inner plexiform, ganglion cell, and outer segment layers of the retina.
=== Availability === Flutamide is marketed widely throughout the world, including in the United States, Canada, Europe, Australia, New Zealand, South Africa, Central and South America, East and Southeast Asia, India, and the Middle East.
==== United States ==== The U.S. Food and Drug Administration (FDA) is the agency responsible for regulation of radiation sources in the United States. Irradiation, as defined by the FDA is a "food additive" as opposed to a food process and therefore falls under the food additive regulations. Each food approved for irradiation has specific guidelines in terms of minimum and maximum dosage as determined safe by the FDA. Packaging materials containing the food processed by irradiation must also undergo approval. The United States Department of Agriculture (USDA) amends these rules for use with meat, poultry, and fresh fruit. The United States Department of Agriculture (USDA) has approved the use of low-level irradiation as an alternative treatment to pesticides for fruits and vegetables that are considered hosts to a number of insect pests, including fruit flies and seed weevils. Under bilateral agreements that allows less-developed countries to earn income through food exports agreements are made to allow them to irradiate fruits and vegetables at low doses to kill insects, so that the food can avoid quarantine. The U.S. Food and Drug Administration and the U.S. Department of Agriculture have approved irradiation of the following foods and purposes:
Sources: en.wikipedia.org
The names are often used interchangeably in casual writing, but they are not strictly identical. Modified GRF(1-29) refers to the unconjugated analogue carrying only the four substitutions. The version sold as CJC-1295 with DAC includes the albumin binding linker and clears much more slowly.
DAC stands for drug affinity complex, a term describing the maleimidopropionic acid linker. This group forms a covalent bond with the cysteine residue on serum albumin after administration. The resulting adduct is what extends the circulating half life from minutes to days.
No. It is entirely synthetic and does not correspond to any known endogenous peptide. The design starts from human growth hormone releasing hormone and introduces deliberate substitutions. Any biological effect comes from mimicking the natural hormone at its receptor.
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.