A practical reference on fatty acid oxidation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| IUPAC name | {4-[({4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-5-yl}methyl)sulfanyl]phenoxy}acetic acid | Systematic name for GW501516 |
| CAS Registry Number | 317318-70-0 | Unique identifier for the parent compound |
| Molecular formula | C21H18F3NO3S2 | Includes carbon, hydrogen, fluorine, nitrogen, oxygen, and sulfur |
| Molecular weight | 453.5 g/mol | Approximate value for the neutral form |
| Appearance | White to off-white powder | Typical description for purified laboratory material |
Anti-doping laboratories detect GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be used in some programs. Detection depends on factors such as dose, timing, metabolism, and the sensitivity of the assay. Published methods describe limits of detection in the low nanogram per milliliter range for related compounds. Exact detection windows are not fixed for all situations and remain an area of ongoing study.
Products sold as cardarine have been found to contain incorrect compounds, variable amounts, or no active ingredient at all. Independent testing is required to verify identity and purity. Common analytical approaches include high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance for structural confirmation. These methods can distinguish GW501516 from related PPAR agonists and from unrelated steroids. For regulators and researchers, such verification is central to interpreting both biological results and adverse event reports.
Human trials of GW501516 were small and short in duration. They examined lipid levels, glucose handling, and other metabolic markers, but the programs were halted after the animal cancer findings. No approved therapeutic product exists, and published human data are insufficient for establishing long-term safety. Reports of use for athletic performance come mainly from non-clinical settings and cannot be verified through controlled trials. Independent testing of products sold as cardarine has found inconsistent purity and labeling.
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.
PPARδ is a nuclear receptor that regulates gene expression related to fatty acid oxidation, glucose homeostasis, and mitochondrial function. GW501516 binds to this receptor with high affinity and activates downstream signaling in skeletal muscle and other tissues. Animal studies reported increased endurance and altered fuel preference, but human data remain limited and inconsistent. The precise relationship between receptor activation and observed physiological changes is still an area of active investigation. Researchers have also examined whether the compound affects inflammation or cell proliferation. No approved therapeutic indication exists for cardarine.
In laboratory settings, cardarine is studied as a tool compound for probing PPARδ biology. Published experiments often use cell cultures, rodent models, or isolated tissues. Some investigations focus on metabolic effects, while others assess potential risks such as carcinogenicity observed in long-term animal studies. Because human trials are sparse, most knowledge comes from preclinical work and adverse event reports. Scientific literature frequently notes the gap between animal findings and human outcomes. The compound is not a dietary supplement and is not intended for human consumption.
Vancomycin, an intravenous antibiotic for treatment of complicated skin infections, bloodstream infections, endocarditis, bone and joint infections, and meningitis. Alteplase, an intravenous "blood clot buster" used for treatment of ischemic stroke. Carmustine, a chemotherapy drug used for treatment of glioblastoma, brainstem glioma, and other brain tumors.
Human (and other eukaryote) cells can produce ATP from glucose without oxygen in a process called glycolysis. This is not as efficient as respiration, but provides a high instantaneous output, and is hence used by some muscle cells. Glycolysis consumes ADP, Pi, glucose, and NAD+ to produce ATP, pyruvate, and NADH. Through lactate fermentation, pyruvate and NADH are turned into lactate and NAD+, thereby regenerating the NAD+ required for more glycolysis. During the 1990s, the lactic acid hypothesis was created to explain why people experienced burning or muscle cramps that occurred during and after intense exercise. The hypothesis proposes that a lack of oxygen in muscle cells results in a switch from cellular respiration to fermentation. Lactic acid created as a byproduct of fermentation of pyruvate from glycolysis accumulates in muscles causing a burning sensation and cramps. Research from 2006 has suggested that acidosis isn't the main cause of muscle cramps. Instead cramps may be due to a lack of potassium in muscles, leading to contractions under high stress. Animals, in fact, do not produce lactic acid during fermentation. Despite the common use of the term lactic acid in the literature, the byproduct of fermentation in animal cells is lactate. Another change to the lactic acid hypothesis is that when sodium lactate is inside of the body, there is a higher period of exhaustion in the host after a period of exercise.
On 9 October 1945, General Leclerc arrived in Saigon, accompanied by French Colonel Massu's Groupement de marche unit. Leclerc's primary objectives were to restore public order in south Vietnam and to militarize Tonkin (northern Vietnam). Secondary objectives were to explore taking back Chinese-occupied Hanoi, and to negotiate with Việt Minh officials. While the Chinese soldiers occupied northern Indochina, Ho Chi Minh's Viet Minh tried to appease the Chinese soldiers with welcome parades in Hanoi and Haiphong, while reassuring the Vietnamese people that China supported Vietnam's independence. Viet Minh newspapers emphasized the common ancestry (huyết thống) and culture shared by Vietnamese and Chinese, and their common struggle against western imperialists, and expressed admiration for the 1911 revolution and anti-Japanese war which had made it "not the same as feudal China". In September 1945, Ho Chi Minh called on the people to contribute gold to purchase weapons for the Viet Minh and also gifts for the Chinese, presenting a golden opium pipe to the Chinese general Lu Han. Lu Han pressured Ho Chi Minh for rice to feed the Chinese occupation force. Rice sent to Cochinchina by the French in October 1945 was divided by Ho Chi Minh, with only one third to the northern Vietnamese and two thirds to the Chinese. After 18 December 1945, elections were postponed for 15 days in response to a demand by Chinese general Chen Xiuhe to allow the Dong Minh Hoi and VNQDD to prepare.
=== Activation === Toll-like receptors (TLRs) are signaling PRRs, capable of recognizing various bacterial proteins. Although bacteria have evolved means of evading host defense mechanisms, they express PAMPs, such as lipoglycans and lipoproteins that are recognized by cells of the innate immune system through the TLRs. Upon binding of PAMPs to TLRs, the TLR triggers inflammatory and defensive responses in the host cell, inducing actin polymerization in alveolar macrophages (a crucial component in endocytosis and motility). Actin polymerization in alveolar macrophages causes the suppression of integrin expression, which in turn causes the deactivation of TGF-β and the downregulation of the basal phosphorylation level of SMAD 2/3; subsequently leading to the activation and detachment of alveolar macrophages from the alveolar epithelial cells [15]. Upon activation, macrophages become primed for phagocytosis and begin to secrete proinflammatory cytokines (TNF-α and IL-6). The priming of macrophages involves the enhancement of respiratory burst activity by IFN-γ and TNF-α. IFNγ induces both an increased affinity of the NADPH oxidase for NADPH in macrophages, as well as an increased rate of gene transcription and message expression for gp91phox protein. TNF-α acts as an autocrine stimulus by increasing the expression of both p47phox and p67phox transcripts. The ROIs produced during the respiration burst response, in turn, enhance production of TNF-α by macrophages.
Extracellular polymeric substances (EPS) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPS establish the functional and structural integrity of biofilms, and are considered the fundamental component that determines the physicochemical properties of a biofilm. EPS in the matrix of biofilms provides compositional support and protection of microbial communities from the harsh environments. Components of EPS can be of different classes of polysaccharides, lipids, nucleic acids, proteins, lipopolysaccharides, and minerals.
Sources: en.wikipedia.org
=== Genome-scale screening === Genome-scale RNAi research relies on high-throughput screening (HTS) technology. RNAi HTS technology allows genome-wide loss-of-function screening and is broadly used in the identification of genes associated with specific phenotypes. This technology has been hailed as a potential second genomics wave, following the first genomics wave of gene expression microarray and single nucleotide polymorphism discovery platforms. One major advantage of genome-scale RNAi screening is its ability to simultaneously interrogate thousands of genes. With the ability to generate a large amount of data per experiment, genome-scale RNAi screening has led to an explosion of data generation rates. Exploiting such large data sets is a fundamental challenge, requiring suitable statistics/bioinformatics methods. The basic process of cell-based RNAi screening includes the choice of an RNAi library, robust and stable cell types, transfection with RNAi agents, treatment/incubation, signal detection, analysis and identification of important genes or therapeutical targets.
=== Antiphospholipid syndrome === Patients with anti-cardiolipin antibodies (Antiphospholipid syndrome) can have recurrent thrombotic events even early in their mid- to late-teen years. These events can occur in vessels in which thrombosis may be relatively uncommon, such as the hepatic or renal veins. These antibodies are usually picked up in young women with recurrent spontaneous abortions. In anti-cardiolipin-mediated autoimmune disease, there is a dependency on the apolipoprotein H for recognition.
On July 25, 2018, the Ford government passed Bill 2, which "put a severe dent into the operations of Hydro One", a former Crown corporation which went public in November 2015. The Toronto-based Hydro One is the province's "largest electricity transmission and distribution service provider" with "nearly 1.4 million customers". Hydro One was established under the Business Corporations Act Crown corporation under the Government of Ontario. Bill 2 places a cap on the compensation allowed for executive members of the board of directors, and gave Ford's provincial government a "direct say in the naming of directors" representing a major shift from what was agreed upon between shareholders and the government when Hydro One went public three years earlier. Under Premier Ford, the CEO and the entire board of directors were replaced. The former CEO, Mayo Schmidt was replaced by Tim Hodgson, a Ford appointee, who took on his new position in August 2019 with an annual salary of $120,000. Hydro One was in the process of acquiring American energy firm Avista Inc., when "U.S. regulators scuttled" the purchase "costing the Toronto-based company a $140 million termination penalty." The Washington Utilities and Transportation Commission said that they blocked the purchase of Avista because of concerns about the independence of Hydro One from the Ontario provincial government. Reducing Ontario consumer electricity costs by 12% was one of the campaign promises made by the Conservative Party. government had promised to cut consumers' electricity prices 12%.
=== Photo-biomodulation therapy (PBMT) mechanism === Photobiomodulation therapy (PBMT) uses low-power densities and is characterized by its non-heat producing effects, a feature previously associated only with laser light. Nowadays, low-level LED lights offer a cost-effective alternative, expanding the accessibility and application of this therapeutic approach. PBMT (low-level light) targets mitochondria and has impacts on, 1) raising ROS levels, 2) creating adenosine triphosphate (ATP); and 3) helping to turn on transcription factor. That can trigger biochemical change within the cells, involve photon emitting light absorbed by the photoreceptor and cascade reaction. When exposed to LED light, the cytochrome c oxidase (CCO) inside the electron transport chain (ETC) of mitochondria is targeted. Its two heme and two copper subunits are oxidized or reduced, enabling it to absorb light at various wavelengths. CCO is the main target of near-infrared and red(650-1000 nm) wavelengths. Cytochrome c oxidase (CCO) is a key protein in the Electron Transport Chain, responsible for transferring electrons to the final oxygen acceptor. This action helps build a substantial proton gradient across the inter-membrane space of mitochondria; a process critical for the synthesis of ATP (Adenosine Triphosphate). The increased production of ATP because of this activity. CCO is also a photoreceptor, the photon absorption of CCO can lead to enhanced enzyme activity, increased oxygen consumption and usage of ATP production and the release of NO (nitric oxide).
Sources: en.wikipedia.org
No. Major drug regulators have not approved GW501516 for treating any medical condition. Products sold as cardarine are typically unapproved research chemicals or supplements, so their contents and safety are not assured.
It is prohibited by the World Anti-Doping Agency as a hormone and metabolic modulator. Athletes who test positive for GW501516 can face sanctions, including suspensions and loss of results.
Cardarine is a common or trade-style name, while GW501516 is the research code for the same chemical entity. Some sources also use Endurobol or GSK-516. The names refer to the same compound, not distinct drugs.
Yes, WADA prohibits cardarine as a PPARδ agonist. It appears on the prohibited list and can be detected in urine or blood. Athletes using it risk sanctions.