If you have been reading about LC-MS/MS 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 2025-08-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
Anti-doping laboratories identify GW501516 and related metabolites using liquid chromatography coupled with tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be analyzed. The method targets the parent compound and phase I and phase II metabolites, which extend the detection window. Because the substance is prohibited at all times, athletes can be tested outside competition. Detection limits and windows depend on the assay, sample type, and individual metabolism.
Cardarine is frequently described as a fat-burning or endurance-enhancing supplement, but these claims exceed the available evidence. The compound is not a hormone, steroid, or selective androgen receptor modulator. Research articles discuss it as a tool compound for studying PPARδ biology, while anti-doping literature focuses on its abuse and detection. Quality of unapproved products is uncertain, and independent analyses have found impurities or incorrect labeling. Open questions include whether human cancer risk resembles that seen in rodents and how often non-athletes use the substance.
Cardarine has no approved therapeutic indication and is not marketed as a medicine. The World Anti-Doping Agency lists GW501516 as a prohibited substance at all times, covering both in-competition and out-of-competition periods. National laws vary: some countries treat it as an unapproved drug subject to import controls, while others have specific restrictions on sale for human consumption. It is often sold as a research chemical, a label that does not imply safety or legality. Enforcement actions have targeted online vendors and shipments.
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 |
|---|---|---|
| Regulatory status | Prohibited in sport; not approved as medicine | Listed by WADA at all times. |
| Common synonyms | GW501516, GW-501516, endurobol | Cardarine is a colloquial name. |
| Typical analytical method | LC-MS/MS | Detects parent compound and metabolites. |
| Common test matrix | Urine | Blood and dried blood spots also possible. |
| Legal classification | Varies by country | Often treated as unapproved drug or research chemical. |
Cardarine is a common name for GW501516, a synthetic compound first described in the 1990s as a selective agonist of the peroxisome proliferator-activated receptor delta. It was studied in preclinical models for metabolic and cardiovascular conditions, but it has not been approved as a medicine in the United States, Europe, or other major jurisdictions. Retail products labeled as cardarine are generally research chemicals or supplements, not pharmaceutical formulations. Because human safety and efficacy data remain limited, regulatory agencies treat it as an unapproved substance rather than a therapeutic product.
Sporting authorities added GW501516 to prohibited lists after it appeared in athlete samples and online markets. The World Anti-Doping Agency classifies it as a hormone and metabolic modulator, and its use can lead to an anti-doping rule violation. Some early laboratory work suggested effects on fatty acid oxidation and endurance-related metabolism in animals, but those findings do not establish safe or effective use in people. Reports of adverse events in humans are scarce and often anecdotal, which complicates risk assessment.
Legal status varies by country. In some places, cardarine is controlled under medicines or psychoactive substances laws; in others, it may be sold with minimal oversight as a research chemical. Customs agencies have intercepted shipments, and several national health agencies have issued warnings about products marketed for bodybuilding or performance enhancement. The lack of a standardized pharmaceutical supply means identity, purity, and contamination levels can differ widely between samples. These factors make cardarine a regulatory and public health concern rather than a conventional prescription drug.
Stability of GW501516 depends on form, temperature, light exposure, and moisture. Solid reference material is typically stored frozen or refrigerated in a desiccator and protected from light. Solutions in organic solvents such as dimethyl sulfoxide are often kept frozen in aliquots to reduce freeze-thaw cycling. Aqueous solubility is low, so aqueous stock solutions can be difficult to prepare without cosolvents. Degradation may appear as changes in chromatographic purity or mass spectral signal. Stability studies are needed to establish shelf life for any specific preparation.
Quality assessment for cardarine samples usually combines identity, purity, and impurity testing. Nuclear magnetic resonance spectroscopy and mass spectrometry can confirm molecular structure, while high-performance liquid chromatography estimates purity. Certificates of analysis from testing laboratories may list these results, but they do not establish safety or legality. In the absence of approved manufacturing, products sold online may contain the wrong compound, variable amounts, or unlisted contaminants. Independent verification is therefore central to analytical work and to interpreting any reported biological activity.
Cardarine is a common name for GW501516, also GW-1516, a synthetic compound developed as a peroxisome proliferator-activated receptor delta (PPARδ) agonist. It belongs to a class of agents that modulate gene transcription related to lipid and energy metabolism. The compound was studied in preclinical and early clinical research for metabolic and cardiovascular conditions, but it did not progress to approved therapeutic use. Its name appears in fitness and sports contexts despite not being approved as a drug.
PPARδ is a nuclear receptor that influences transcription of genes involved in fatty acid oxidation, lipid transport, and energy homeostasis. GW501516 binds and activates this receptor with high selectivity relative to PPARα and PPARγ in laboratory assays. Activation alters expression of target genes in skeletal muscle, liver, and adipose tissue in animal models. The exact clinical consequences of these changes in humans remain incompletely characterized, and observed effects in animals do not establish therapeutic benefit or safety.
Published studies have examined GW501516 in animal models of obesity, insulin resistance, and exercise endurance. Early human trials reportedly ended, and development was discontinued after preclinical findings raised concerns about cancer in some rodent studies. Regulatory agencies have not approved cardarine for any medical use. Its availability through non-pharmaceutical channels raises questions about identity, purity, and legal status that are separate from its laboratory pharmacology. Those questions are often addressed through analytical testing rather than assumptions about product labels.
Laboratory detection of cardarine typically involves sample preparation followed by chromatographic separation and mass spectrometric identification. Urine is the most common matrix for anti-doping tests, though blood and hair have also been explored. Methods can target the parent compound or its metabolites, depending on the expected window of detection. Reference standards are required for accurate quantification. Matrix effects and dilution can influence results, so laboratories use internal standards and validation protocols. The exact detection window varies with dose, route, and individual metabolism.
A common misconception is that cardarine has been proven safe for human use. In reality, human clinical data are limited, and long-term animal studies have raised concerns about cancer. Another misconception is that it is a supplement or vitamin-like compound. It is a synthetic research chemical with no approved medical indication. Scientific discussion often focuses on its mechanism and detection rather than therapeutic use. Regulatory and anti-doping literature treats it primarily as a prohibited substance.
Cardarine is explicitly prohibited by the World Anti-Doping Agency under the class of PPARδ agonists. Its presence in urine or blood samples can be detected using mass spectrometry-based methods, often liquid chromatography-tandem mass spectrometry. Athletes who test positive may face sanctions, including bans from competition. The compound is also regulated as a prescription-only or unapproved drug in many countries. Enforcement varies by jurisdiction, and some regions treat it as a controlled substance. Online sales may occur despite these restrictions, creating quality and legal risks.
Ergothioneine (EGT) is a naturally occurring amino acid and is a thiourea derivative of histidine, containing a sulfur atom on the imidazole ring. This compound occurs in relatively few organisms, notably actinomycetota, cyanobacteria, and certain fungi. Ergothioneine was discovered by Charles Tanret in 1909 and named after the ergot fungus from which it was first purified, with its structure being determined in 1911. Unlike other ergot alkaloids, ergothioneine is not an ergoline derivative. In humans, ergothioneine is acquired exclusively through the diet and accumulates in erythrocytes, bone marrow, liver, kidney, seminal fluid, and eyes. Although the effect of ergothioneine in vivo is under preliminary research, its physiological role in humans is unknown. Ergothioneine is sold as a dietary supplement.
Before submitting their final squad for the World Cup, teams named a provisional squad of between 35 and 55 players one month prior to the tournament. Teams were required to name their final squads by June 2. If a player became too injured or ill to participate in the tournament, he could be replaced by another player from the provisional squad until 24 hours before the team's first match. However, an injured or ill goalkeeper could be replaced by another goalkeeper from the provisional squad at any time during the tournament.
==== Clostridioides difficile diarrhea ==== The first study on dogs used for the detection of infectious diseases was conducted by Bomers et al. in 2012. The dogs were trained with food rewards to detect individuals with C. difficile diarrhea, and the results showed 100% specificity and sensitivity in the detection in stool samples. They were also capable of surveilling C. difficile in the environment with 92.3% sensitivity and 95.4% specificity for both odor detection and the ability to locate the source. Vancouver Canada hospital's canine scent recognition program also reported observing dogs' promising ability to detect C. difficile on hospital surfaces, equipment, and C. difficile reservoirs. The advantage of using trained dogs to detect C. difficile compared to the traditional culture-based diagnostic method is the fast detection speed, which only takes a few minutes. Whether sniffing dogs could be universally employed for diagnosing C. difficile is dubious as although it yields the results faster than the preexisting nucleic amplification test, its responsiveness is significantly lower.
Sources: en.wikipedia.org
X.906|ISO/IEC 19793: Information technology - Open distributed processing - Use of UML for ODP system specifications". This document (usually referred to as UML4ODP) defines use of the Unified Modeling Language 2 (UML 2; ISO/IEC 19505), for expressing the specifications of open distributed systems in terms of the viewpoint specifications defined by the RM-ODP. It defines a set of UML Profiles, one for each viewpoint language and one to express the correspondences between viewpoints, and an approach for structuring them according to the RM-ODP principles. The purpose of "UML4ODP" to allow ODP modelers to use the UML notation for expressing their ODP specifications in a standard graphical way; to allow UML modelers to use the RM-ODP concepts and mechanisms to structure their large UML system specifications according to a mature and standard proposal; and to allow UML tools to be used to process viewpoint specifications, thus facilitating the software design process and the enterprise architecture specification of large software systems. In addition, ITU-T Rec. X.906 | ISO/IEC 19793 enables the seamless integration of the RM-ODP enterprise architecture framework with the Model-Driven Architecture (MDA) initiative from the OMG, and with the service-oriented architecture (SOA).
=== Synthesis using macroscopic units of solid support === Modifications had been developed enabling the split and pool synthesis to produce known compounds in larger quantities than the content of a bead of solid support and retain the high efficiency of the original method. As published by Moran et al. and Nicolau et al. the resin normally used in the solid phase synthesis was enclosed into permeable capsules including a radiofrequency label recording the BBs in order of their coupling. Both manual and automatic machine was constructed to sort the capsules into the appropriate reaction vessels. A different kind of labeled macroscopic solid support unit was introduced by Xiao et al. The supports are 1x1 cm polystyrene grafted square plates. The medium carrying the code is a 3x3 mm ceramic plate in the center of the synthesis support The code is etched into the ceramic support by a CO2 laser in the form of a two-dimensional bar code that can be read by a special scanner.
=== Os cordis === In some animals, the fibrous trigone can undergo increasing mineralization with age, leading to the formation of a significant os cordis (heart bone), or two (os cordis sinistrum and os cordis dextrum, the latter being the larger one). The os cordis is thought to serve mechanical functions. In humans, two paired trigones (left and right) are seen in this essential view of anatomy. As a surgical purchase point, the Trigones risk much in AV propagation. It has been known since Classical times in deer and oxen and was thought to have medicinal properties and mystical properties. It is occasionally observed in many other artiodactyls including goats, sheep, giraffes, camels, water buffalo, and antelopes but also in carnivorans such as otters, dogs, cats, and sea lions and in the horse. It has also been discovered in chimpanzees, the first known great ape to have an os cordis; it has subsequently been reported in a human, though its etiology is unknown. Against the opinion of his time, Galen wrote that the os cordis was also found in elephants. While it is unclear if Galen actually observed the bone, it has since been identified in Asian elephants.
Sources: en.wikipedia.org
==== Collagen deposition ==== One of fibroblasts' most important duties is the production of collagen. Collagen deposition is important because it increases the strength of the wound; before it is laid down, the only thing holding the wound closed is the fibrin-fibronectin clot, which does not provide much resistance to traumatic injury. Also, cells involved in inflammation, angiogenesis, and connective tissue construction attach to, grow and differentiate on the collagen matrix laid down by fibroblasts. Type III collagen and fibronectin generally begin to be produced in appreciable amounts at somewhere between approximately 10 hours and 3 days, depending mainly on wound size. Their deposition peaks at one to three weeks. They are the predominating tensile substances until the later phase of maturation, in which they are replaced by the stronger type I collagen. Even as fibroblasts are producing new collagen, collagenases and other factors degrade it. Shortly after wounding, synthesis exceeds degradation so collagen levels in the wound rise, but later production and degradation become equal so there is no net collagen gain. This homeostasis signals the onset of the later maturation phase. Granulation gradually ceases and fibroblasts decrease in number in the wound once their work is done. At the end of the granulation phase, fibroblasts begin to commit apoptosis, converting granulation tissue from an environment rich in cells to one that consists mainly of collagen.
== Integrins == Integrins function as the major cell receptor for extracellular matrix protein. These receptors comprise an α and β transmembrane subunit, which are noncovalently bound. Collagen binding is primarily provided by integrins α1β1, α2β1, α10β1 and α11β1. Integrin α1β1 binds to collagen via the MIDAS motif in the α subunit I domain. It preferentially binds collagens IV, VI and type XIII collagen, but also fibril-forming collagens. Specific binding sites in collagen I and IV have been identified. This receptor is situated mainly on mesenchymal cells. Functions include: fibroblast proliferation; regulation of collagen synthesis and MMP expression; response to renal injury. Integrin α2β1 preferentially binds fibril-forming collagens. Specific binding sites in collagen I and III have been identified. Integrin α2β1 is expressed mainly on epithelial cells and platelets. Functions include: platelet adhesion - the most abundant receptor for collagen in platelets; branching morphogenesis; mast cell activation; keratinocyte adhesion and it is the main regulator of cell migration. Integrin α10β1 preferentially binds collagens IV and VI, but also collagen II. It is expressed on chondrocytes and cardiac muscle. Involved in growth plate morphogenesis and function. Integrin α11β1 is expressed by mesenchymal cells in some parts of embryo during its development and also in muscles in adults: it preferably binds fibrillar collagen. Integrin receptors capable of collagen binding could, according to results of (Garnotel R et al.
=== Collagen hybridizing peptides === Collagen, the major structural component of nearly all mammalian tissues, undergoes extensive proteolytic remodeling during developmental states and a variety of life-threatening diseases such as cancer, myocardial infarction, and fibrosis. While degraded collagen could be an important marker of tissue damage, it is difficult to detect and target using conventional tools. As a result, a collagen hybridizing peptide is specifically hybridized to the degraded, unfolded collagen chains, can be used to image degraded collagen and inform tissue remodeling activity in various tissues. Labeled with 5-carboxyfluorescein and biotin, the collagen hybridizing peptide can enable direct localization and quantification of collagen degradation in isolated tissues within pathologic states ranging from osteoarthritis and myocardial infarction, to glomerulonephritis and pulmonary fibrosis, as well as in normal tissues during developmental programs associated with embryonic bone formation and skin aging. The general correlation between the level of collagen remodeling and the amount of denatured collagen in tissue, show that the collagen hybridizing peptide probes can be used across species and collagen types (including type IV collagen), providing a versatile tool for not only pathology and developmental biology research, but also disease diagnosis via histology.
During the initial 4 to 6 hours following the power change, the magnitude and the rate of change of concentration is dependent upon the initial power level and on the amount of change in power level; the 135Xe concentration change is greater for a larger change in power level. When reactor power is decreased, the process is reversed. Iodine-135 is a fission product of uranium with a yield of about 6% (counting also the 135I produced almost immediately from decay of fission-produced tellurium-135). This 135I decays with a 6.58 hour half-life to 135Xe. Thus, in an operating nuclear reactor, 135Xe is being continuously produced. 135Xe has a very large neutron absorption cross-section, so in the high-neutron-flux environment of a nuclear reactor core, the 135Xe soon absorbs a neutron and becomes effectively stable 136Xe. (The half-life of 136Xe is >1021 years, and it is not treated as a radioisotope.) Thus, in about 50 hours, the 135Xe concentration reaches equilibrium where its creation by 135I decay is balanced with its destruction by neutron absorption. When reactor power is decreased or shut down by inserting neutron-absorbing control rods, the reactor neutron flux is reduced and the equilibrium shifts initially towards higher 135Xe concentration. The 135Xe concentration peaks about 11 hours after reactor power is decreased. Since 135Xe has a 9.14 hour half-life, the 135Xe concentration gradually decays back to low levels over 72 hours.
Sources: en.wikipedia.org
Legal status varies by country. It is not approved as a medicine, and it is prohibited in sport. Some jurisdictions restrict import, sale, or possession.
Laboratories use liquid chromatography-tandem mass spectrometry to detect GW501516 and its metabolites. Urine is commonly tested, and testing can occur in and out of competition.
No, cardarine is not a SARM. It is a PPARδ agonist, which acts on a different receptor. The two classes are often confused in online discussions.
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.