LC-MS/MS raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Detection of GW501516 in biological samples generally relies on liquid chromatography coupled with tandem mass spectrometry. Urine is a common matrix in anti-doping analysis, while blood or plasma may be used in research settings. Sample preparation can involve enzymatic hydrolysis, protein precipitation, or solid-phase extraction before instrumental analysis. Because the compound undergoes metabolism, assays may target the parent molecule, one or more metabolites, or both. Detection windows are not fixed; they depend on factors such as dose, route, individual metabolism, and assay sensitivity. Reference standards are required for accurate identification and quantification.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s methods.
GW501516 acts as an agonist at the peroxisome proliferator-activated receptor delta, a nuclear receptor that regulates gene expression. Activation shifts transcription toward genes involved in fatty acid uptake, oxidation, and energy expenditure. The compound does not bind the androgen receptor and therefore differs from anabolic steroids and SARMs. In rodent models, this metabolic shift has been linked to increased running endurance and reduced fat accumulation. The exact downstream pathways in humans remain incompletely characterized.
Early clinical research explored GW501516 for lipid disorders, obesity, and diabetes. Some short-term human studies reported changes in HDL cholesterol, LDL cholesterol, and triglycerides. The development program was discontinued after rodent studies showed dose-dependent tumor formation in multiple tissues, including liver, bladder, stomach, and skin. These findings raised concerns about long-term cancer risk in humans. Because human exposure data are limited, the clinical significance of the rodent tumors remains uncertain.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Visual description for typical solid reference material. |
| Solubility | Poorly soluble in water; soluble in DMSO | Solubility depends on solvent, purity, and form. |
| Storage | Cool, dry, protected from light | Long-term storage often uses low temperature and desiccant. |
| Common analytical method | LC-MS/MS | Used for detection and quantification in biological matrices. |
| Common synonyms | GW-501516; GW501516; endurobol | Naming varies among literature, vendors, and databases. |
Cardarine is a synthetic compound also known as GW501516, GW-501516, and sometimes endurobol. It was developed as a selective agonist of peroxisome proliferator-activated receptor delta, a nuclear receptor involved in fatty acid oxidation and energy metabolism. The compound was studied in preclinical models for metabolic and cardiovascular conditions, but it did not become a marketed human medicine. In regulatory and anti-doping contexts, it is treated as a prohibited substance rather than a licensed medicine.
The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.
Safety discussions about cardarine frequently cite rodent carcinogenicity findings reported in the 2000s. In those studies, treated animals developed tumors at multiple sites, leading sponsors to discontinue clinical development. The relevance of these findings to humans has not been resolved, but they are a major reason the compound is not approved. Current literature emphasizes uncertainty about long-term effects and the risks of unregulated use. Regulators and health agencies have not established a safe human exposure level.
Laboratory studies indicate that GW501516 activates PPARδ, a nuclear receptor involved in fatty acid oxidation and energy metabolism. In rodent experiments, treated animals often showed increased endurance and reduced fat mass. These effects were observed under controlled conditions and do not establish safe or effective use in humans. The exact dose-response relationship in humans remains poorly characterized. Species differences in metabolism can affect how results translate across animals and people.
Safety concerns emerged from long-term animal studies. In rodents given the compound for extended periods, researchers found an increased incidence of certain cancers, including liver and bladder tumors. These findings contributed to the discontinuation of clinical development. Whether similar risks apply to short-term or low-level exposure in humans is not established, and controlled human safety data are limited. The relevance of high-dose rodent carcinogenicity findings to human use remains a subject of debate.
==== Lieutenant of the Royal Victorian Order (LVO) ==== Ian Scott Anderson, , Director, The Duke of Edinburgh's Commonwealth Study Conferences. Mark Appleby, Crown Jeweller. Colonel Jeremy David Bagshaw, , Late Coldstream Guards, 534873; lately Chief of Staff, London District, on the occasion of the Coronation of Their Majesties The King and The Queen. Major Grant Vincent Ashley Baker, Gentleman Usher to His Majesty The King. Paul David Baumann, , Receiver-General, Westminster Abbey, on the occasion of the Coronation of Their Majesties The King and The Queen. Charles Harcourt James Davies, , Private Secretary to The Princess Royal. Karen Ross Findlay, Commander, Metropolitan Police Service, on the occasion of the Coronation of Their Majesties The King and The Queen. Dr Michael Terence Isaac, Occupational Health Advisor to the Royal Household. Air Vice-Marshal Richard Howard Lacey, , lately Gentleman Usher to His Majesty The King. Charlotte Elizabeth Martin, , Deputy Head of Ceremonial, Royal Household. Jonathan David Rogerson Martin, Director of Ceremonials, Department for Culture, Media and Sport, on the occasion of the Coronation of Their Majesties The King and The Queen. Ian Donald McCowan, lately Secretary to the Governor-General of Canada. Professor Paul Mealor, Music Advisor, Honours of Scotland Service. Graham Paul Midgley, Head of Royal Travel, Royal Household. Gavin Donald Reid, Music Advisor, Honours of Scotland Service. Paul John Sedwick, Deputy Ranger, Windsor Great Park.
was renamed Merck Sharp & Dohme, and Schering-Plough renamed as "Merck & Co., Inc." The maneuver was an attempt to avoid a "change-of-control" in order to preserve Schering-Plough's rights to market Remicade. A settlement with Johnson & Johnson was reached in 2011, in which Merck agreed to pay $500 million. Merck Sharp & Dohme remains a subsidiary of the Merck & Co. parent. Richard Clark retired as CEO and company president in October 2011 and Kenneth Frazier became CEO. In October 2013, Merck announced it would cut 8,500 jobs in an attempt to cut $2.5 billion from its costs by 2015. Combined with 7,500 job cuts announced in 2011 and 2012, the layoffs amounted to 20% of its workforce. By 2014, research performed at Merck has led to U.S. FDA approval of 63 new molecular entities. In August 2014, Merck acquired Idenix Pharmaceuticals for $3.85 billion. In September 2014, the US Food and Drug Administration (FDA) approved Pembrolizumab (MK-3475) as a breakthrough therapy for melanoma treatment. In clinical trials, pembrolizumab provided partial tumor regression in about one quarter of patients, many of whom have not seen further progression of their disease in over 6 months of follow-up. In December 2014, the company acquired Swiss biotechnology company OncoEthix for up to $375 million. Between 2010 and 2015, the company cut around 36,450 jobs. During that time, the company sold its consumer health business to Bayer and narrowed the company's focus to immunology, vaccines, diabetes, emerging markets and medicines used in hospitals, like certain antibiotics.
== Trials == Howard Florey's team at Oxford showed that Penicillium extract killed many kinds of bacteria. Gardner and Orr-Ewing tested it against gonococcus (against which it was most effective), meningococcus, streptococcus, staphylococcus, Bacillus anthracis, actinomyces and tetanus bacterium (Clostridium tetani) and the bacteria that cause gangrene. They observed bacteria attempting to grow in the presence of penicillin, and noted that penicillin was neither an enzyme that broke the bacteria down, nor an antiseptic that killed them; rather, it was a chemical that interfered with the process of cell division. Jennings observed that it had no effect on white blood cells, and would therefore reinforce rather than hinder the body's natural defences against bacteria. She also found that unlike sulphonamides, the first and only effective broad-spectrum antibiotic available at the time, it was not destroyed by pus. Medawar found that it did not affect the growth of tissue cells.
Sources: en.wikipedia.org
=== Category:EC 5.1 (racemases and epimerases) === Category:EC 5.1.1 Amino-acid racemase: Phenylalanine racemase (ATP-hydrolysing) Serine racemase Category:EC 5.1.2 Mandelate racemase Category:EC 5.1.3 UDP-glucose 4-epimerase Category:EC 5.1.99 Methylmalonyl CoA epimerase
=== Paracetamol === Mechanism of action: Paracetamol acts to inhibit COX enzyme, which is responsible for prostaglandin synthesis. Prostaglandins increase the perception of pain. Inhibition of prostaglandin production helps to alleviate pain. Absorption/distribution: The half-life of oral paracetamol is 1.25 to 3 hours and peak level is reached by 10–60 minutes after ingestion. Metabolism/excretion: Paracetamol is metabolized primarily in the liver via glucuronidation and sulfation to mostly non-toxic metabolites and some highly reactive metabolites, which is inactivated by glutathione. 85% of the oral dose is excreted via the kidneys. At high doses, the supply of glutathione cannot meet its demand, thus resulting in the accumulation of highly reactive compounds leading to liver damage.
The monoepoxide of treosulfan (EBDM) exhibited greater brain penetration than the parent compound, with tissue-to-plasma ratios of 0.25 in young adult rats and 0.50 in juvenile rats. The elimination half-life of treosulfan in patients is short, averaging 1.5–2.0 h. The apparent elimination half-life of the biologically active epoxides is similar to that of treosulfan, reflecting the phenomenon of formation rate-limited elimination. The most common side effects include infections, nausea (feeling sick), stomatitis (inflammation of the lining of the mouth), vomiting, diarrhea, and abdominal pain (belly ache). Tiredness, febrile neutropenia (low white blood cell counts with fever) and high blood levels of bilirubin (a breakdown product of red blood cells) are also seen in more than 1 in 10 adults, and rash also affects more than 1 in 10 children. The most common adverse reactions include musculoskeletal pain, stomatitis, pyrexia, nausea, edema, infection, and vomiting. Selected grade 3 or 4 nonhematological laboratory abnormalities include increased GGT, increased bilirubin, increased ALT, increased AST, and increased creatinine. Treosulfan was authorized for medical use in the European Union in June 2019, and approved for medical use in the United States in January 2025.
Sources: en.wikipedia.org
==== Mass-sensitive peptide biosensors ==== Mass-sensitive Peptide Biosensors make use of platforms like quartz crystal microbalance (QCM) or piezoelectric sensors. These biosensors detect changes in mass or resonance frequency upon target binding, providing a label-free detection in real time. Because they function label-free and are efficient in identifying cells, virion, poisons, and large biomacromolecules since the signal is directly dependent on mass accumulation.
The canonical example of a ligand-binding protein is haemoglobin, which transports oxygen from the lungs to other organs and tissues in all vertebrates and has close homologs in every biological kingdom. Lectins are sugar-binding proteins which are highly specific for their sugar moieties. Lectins typically play a role in biological recognition phenomena involving cells and proteins. Receptors are highly specific binding proteins, and many hormones act by binding specifically to their receptors. Transmembrane proteins can serve as ligand transport proteins that alter the permeability of the cell membrane to small molecules and ions. The membrane alone has a hydrophobic core through which polar or charged molecules cannot diffuse. Membrane proteins contain internal channels that allow such molecules to enter and exit the cell. Many ion channel proteins are specialized to select for only a particular ion; for example, potassium and sodium channels often discriminate for only one of the two ions.
== Diagnosis == The disease may be diagnosed based on a clinical examination, which identifies signs and symptoms generally associated with the people who have the condition. Genetic testing for known pathological variants is preferred, by testing of the COL6A1, COL6A2, COL6A3 and COL12A1 genes. In the case of a VUS, testing of dermal fibroblast culture is used for an accurate diagnosis. Additional laboratory tests may be performed before genetic testing, such as creatine kinase (CK) blood test, MRI of the muscles, and electromyography (EMG). Phenotypes of overlap between Ullrich congenital muscular dystrophy (UCMD) and Bethlem can be assumed. In the differential diagnosis of UCMD, even in patients without finger contractures, Bethlem myopathy could be considered.
Sources: en.wikipedia.org
Cardarine targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not bind the androgen receptor in the way SARMs do.
Most methods use liquid chromatography with tandem mass spectrometry. Urine is common in anti-doping testing, and blood or plasma may be used in research.
Typical guidance is cool, dry, dark storage, often at low temperature and with desiccant. Stability data are limited, so storage conditions should be verified for each batch or supplier.
It targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not act primarily on androgen receptors. This distinction separates it from SARMs.