If you have been reading about mass spectrometry 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.
Updated 2026-01-21. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Lyophilized peptide powder is comparatively stable when kept dry, cold, and protected from light. Once dissolved, the molecule is vulnerable to deamidation, oxidation, and aggregation, with the rate depending on pH, buffer composition, and temperature. Alkaline conditions and repeated freeze-thaw cycles accelerate loss of the intact peptide. The methionine present in the native sequence is a known oxidation site, which is one reason it was replaced in the modified fragment. Suppliers typically recommend cold storage of solutions and use within a short window.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular mass | Approximately 3.4 to 3.6 kDa | Depends on whether the affinity complex is attached |
| Appearance | White to off-white lyophilized powder | Freeze-dried solid, often in a sealed vial |
| Solubility | Soluble in water and aqueous buffers | Dissolution rate varies with pH and buffer salt |
| Typical storage | Below minus 20 degrees Celsius, dry and dark | Dissolved material is usually kept cold and used promptly |
| Common analytical methods | Reversed-phase HPLC and mass spectrometry | Peptide mapping and amino acid analysis add sequence detail |
The peptide backbone corresponds to GRF(1-29), the first 29 residues of native growth hormone-releasing hormone, which retains most of the receptor-activating activity of the full-length molecule. Four substitutions distinguish the analog from the natural sequence: D-alanine at position 2, glutamine at position 8, alanine at position 15, and leucine at position 27. These changes slow cleavage by dipeptidyl peptidase IV, the enzyme that degrades native hormone in plasma within minutes. The outcome is improved enzymatic stability combined with a still brief residence time when no additional modification is present.
Naming in this area is inconsistent, and readers should treat product labels with care. In much of the literature and in vendor catalogs, the unqualified term refers to the albumin-binding version, while the version lacking the DAC group appears as modified GRF(1-29), mod GRF(1-29), or the same name with a without-DAC qualifier. Because one abbreviation has been applied to both materials, the only reliable way to identify a sample is to check the stated sequence and the presence of the linker.
Lyophilised powder is the usual supplied form. The material is hygroscopic, so vials are typically equilibrated to room temperature before opening in order to prevent condensation on the contents. Long-term storage is generally described at minus twenty degrees Celsius or colder, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of soluble material. A reconstituted solution is considerably less stable than the dry powder and is normally kept refrigerated for short periods only.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography combined with mass spectrometry. The chromatographic separation resolves the target peptide from truncation products and from species carrying oxidised residues, while mass measurement confirms the expected molecular mass. Because the two common variants differ by roughly 280 daltons, a mass determination distinguishes them unambiguously. Purity is often quoted as a percentage of total peak area, although that figure depends on the detection wavelength and the integration method applied.
Reported half-lives differ widely between the two variants and between species. Values for the albumin-binding form are usually expressed in days, while the unconjugated form is measured in minutes to a few hours. Sampling schedules, assay sensitivity, and route of administration all influence the numbers, which limits direct comparison across studies. Whether sustained receptor occupancy produces different downstream effects from pulsatile stimulation remains an open question in the published work. Claims about relative potency should therefore be read alongside the specific study design that produced them.
The compound emerged from work at a Canadian biotechnology firm in the early 2000s. Early human studies examined its effect on growth hormone and insulin-like growth factor 1 in healthy volunteers and in people with HIV-associated fat redistribution. Reports described sustained increases in both markers after a single injection. Development did not advance to regulatory approval, and the clinical programme was later discontinued. The molecule is now encountered mainly as a research chemical rather than a marketed medicine.
Two forms circulate in research settings and are frequently confused. One carries the drug affinity complex and is often written as CJC-1295 with DAC; the other lacks that group and is usually called modified GRF(1-29). The two share the same core sequence but differ sharply in how long they persist in blood. Products labelled only as CJC-1295 normally refer to the version carrying the complex. Documentation that omits the distinction leaves the intended molecule ambiguous.
CJC-1295 is a synthetic peptide built as a long-acting analogue of growth hormone-releasing hormone. Its backbone matches the first twenty-nine residues of the natural human hormone, with four amino acid substitutions added to slow enzymatic breakdown. A reactive maleimide group, commonly termed the drug affinity complex, allows the peptide to attach to circulating albumin after administration. That albumin attachment keeps the molecule in the bloodstream for an extended period instead of being cleared within minutes.
ectopic Occurring or developing in an abnormal place or position or in an unusual form or manner; displaced, malpositioned, or produced in an unnatural context. For example, ectopic expression refers to the expression of a particular gene product in a cell or tissue where it is not normally expressed. Contrast entopic.
Morphine, formerly known as morphium, is an opiate found naturally in opium, a dark brown resin produced by drying the latex of opium poppies (Papaver somniferum). It is mainly used as an analgesic (pain medication). There are multiple methods used to administer morphine: oral; sublingual; via inhalation; injection into a muscle, injection under the skin, or injection into the spinal cord area; transdermal; intravenously; or via rectal suppository. It acts directly on the central nervous system (CNS) to induce analgesia and alter perception and emotional response to pain. Physical and psychological dependence and tolerance may develop with repeated administration. It can be taken for both acute pain and chronic pain and is frequently used for pain from myocardial infarction, kidney stones, and during labor. Its maximum effect is reached after about 20 minutes when administered intravenously and 60 minutes when administered by mouth, while the duration of its effect is 3–7 hours. Long-acting formulations of morphine are sold under the brand names MS Contin and Kadian, among others. Generic long-acting formulations are also available. Common side effects of morphine include drowsiness, euphoria, nausea, dizziness, sweating, and constipation. Potentially serious side effects of morphine include decreased respiratory effort, vomiting, and low blood pressure. Morphine is highly addictive and prone to abuse. If one's dose is reduced after long-term use, opioid withdrawal symptoms may occur.
Microchimerism is the presence of a small number of cells in an individual that have originated from another individual and are therefore genetically distinct. This phenomenon may be related to certain types of autoimmune diseases although the responsible mechanisms are unclear. The term comes from the prefix "micro" + "chimerism" based on the hybrid Chimera of Greek mythology. The concept was first discovered in the 1960s with the term gaining usage in the 1970s.
Sources: en.wikipedia.org
=== Differential diagnosis === Cervical radiculopathy can also cause paresthesia and abnormal sensibility in the hands and wrist. The distribution usually follows the nerve root, and the paresthesia may be provoked by neck movement. Electromyography and imaging of the cervical spine can help to differentiate cervical radiculopathy from carpal tunnel syndrome if the diagnosis is unclear. Carpal tunnel syndrome is sometimes applied as a label to anyone with pain, numbness, swelling, or burning in the radial side of the hands or wrists. When pain is the primary symptom, carpal tunnel syndrome is unlikely to be the source of the symptoms. When the symptoms and signs point to atrophy and muscle weakness more than numbness, consider neurodegenerative disorders such as Amyotrophic Lateral Sclerosis or Charcot-Marie Tooth.
== L == Larock indole synthesis Lawesson's reagent Lebedev process Lehmstedt–Tanasescu reaction Leimgruber–Batcho indole synthesis Letts nitrile synthesis Leuckart reaction Leuckart thiophenol reaction Leuckart–Wallach reaction Leuckart amide synthesis Levinstein process Ley–Griffith oxidation, Ley oxidation Lieben iodoform reaction, Haloform reaction Liebeskind–Srogl coupling Liebig melamine synthesis Lindlar catalyst Lobry de Bruyn–Van Ekenstein transformation Lombardo methylenation Lossen rearrangement Lucas' reagent Luche reduction
== Research == Baclofen is being studied for the treatment of alcoholism. Evidence as of 2019 is not conclusive enough to recommend its use for this purpose. In 2014, the French drug agency ANSM issued a three-year temporary recommendation allowing the use of baclofen in alcoholism. In 2018, baclofen received a Marketing Authorization for use in alcoholism treatment from the agency if all other treatments are not effective. It is being studied along with naltrexone and sorbitol for Charcot–Marie–Tooth disease (CMT), a hereditary disease that causes peripheral neuropathy. It is also being studied for cocaine addiction. Baclofen and other muscle relaxants are being studied for potential use for persistent hiccups. From 2014 to 2017, baclofen misuse, toxicity and use in suicide attempts among adults in the US increased. In his 2008 book, Le Dernier Verre (translated literally as The Last Glass or The End of My Addiction), French-American cardiologist Olivier Ameisen described how he treated his alcoholism with baclofen. Inspired by this book, an anonymous donor gave $750,000 to the University of Amsterdam in the Netherlands to initiate a clinical trial of high-dose baclofen, which Ameisen had called for since 2004. The researchers concluded, "In summary, the current study did not find evidence of a positive effect of either low or high doses of baclofen in AD patients. However, we cannot exclude the possibility that baclofen is an effective medication for the treatment of severe, heavy drinking AD patients not responding to or not accepting routine psychosocial interventions."
== External links == AmBisome Summaries of Product Characteristics (United Kingdom) Amphotericin B "Amphotericin B Liposomal Injection". MedlinePlus. "Amphotericin B Lipid Complex Injection". MedlinePlus.
Sources: en.wikipedia.org
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.
In common usage the name without the affinity complex is often equated with MOD GRF 1-29, a fragment carrying four stabilizing substitutions. Strictly speaking, the term originally referred to the albumin-binding version. The overlap in naming causes frequent ambiguity in both informal and technical writing.
Reversed-phase chromatography separates the peptide from related impurities and yields a purity estimate. Mass spectrometry confirms the molecular mass and detects modifications such as oxidation. Sequence-level checks rely on peptide mapping or amino acid analysis when stronger confirmation is needed.
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.