If you have been reading about Nuclear receptor 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 2026-05-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
Cardarine is the common name for GW501516, a synthetic compound studied as a peroxisome proliferator-activated receptor delta agonist. Researchers developed it to explore treatments for lipid disorders and metabolic conditions. It is not an approved medicine in any country. Early clinical work examined changes in HDL cholesterol and triglycerides, but development was discontinued after animal studies raised concerns about cancer. The compound remains available as a research chemical and appears in discussions of performance enhancement.
At the molecular level, GW501516 binds and activates PPARδ, a nuclear receptor that regulates transcription. Activation shifts expression of genes involved in fatty acid oxidation, energy expenditure, and lipid transport in skeletal muscle and liver. Animal studies report increased endurance and altered lipid profiles after exposure. Human data are limited to small trials and do not establish long-term safety or efficacy. PPARδ also has roles in cell proliferation, so the relationship between activation and cancer risk remains an open question.
Published literature on cardarine includes in vitro assays, rodent experiments, and a small number of human studies. Reports describe effects on exercise capacity and lipid metabolism in animals, while human evidence is sparse. Many online descriptions present the compound as a proven endurance aid, a claim not supported by regulatory approval or large clinical trials. Analytical studies focus on identifying the parent compound and its metabolites in biological samples. Important uncertainties include species differences, dose-response relationships, and the relevance of rodent tumor findings to humans.
Cardarine can be detected in biological samples and product materials using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method separates compounds by chromatography and identifies them by mass-to-charge transitions, allowing low-level detection in urine or blood. Sample preparation often involves enzymatic hydrolysis, solid-phase extraction, or protein precipitation. Certified reference materials and isotope-labeled internal standards improve quantification. Detection windows depend on metabolism, matrix, and assay sensitivity, so no single universal window applies.
Regulatory treatment of cardarine differs by context and jurisdiction. In competitive sport, the World Anti-Doping Agency lists PPARδ agonists, including GW501516, as prohibited at all times. Outside sport, it lacks approval as a prescription medicine in major drug markets, and products sold for human consumption may be treated as unapproved drugs. Some countries also restrict importation or sale through general consumer protection and medicines laws. These classifications affect availability, testing, and legal risk without establishing therapeutic value.
Because cardarine is not an approved medicine, no pharmacopeial monograph defines its identity, purity, or storage requirements. Laboratories typically rely on in-house methods and reference standards when testing materials labeled as GW501516. Certificates of analysis may report purity and identity for a specific batch, but their scope varies and they do not guarantee safety or legal status. Independent verification can include high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance, and elemental analysis. The distinction between research chemical labeling and human use is significant because quality standards and oversight differ.
| Property | Value | Notes |
|---|---|---|
| Common name | Cardarine | Also called GW501516 and endurobol. |
| Chemical formula | C21H18F3NO3S2 | Molecular weight about 453.5 g/mol. |
| Appearance | White to off-white solid | Form depends on synthesis and purity. |
| Solubility | Soluble in DMSO and ethanol | Low solubility in water. |
| Typical storage | -20 °C, desiccated, protected from light | Common for research chemicals. |
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.
Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.
A persistent misconception is that cardarine is a fat-burning drug or a safe alternative to anabolic steroids. No approved therapeutic product exists, and human safety data are limited. The tumor findings in rodents remain a central concern in scientific reviews. Products sold online may contain inaccurate labels, impurities, or different compounds entirely, which complicates any assessment of effects. Independent testing of such products has reported frequent mislabeling. For these reasons, discussions in the literature emphasize risks and unknowns rather than benefits.
Cardarine is not approved for human therapeutic use in any major jurisdiction. It appears on the World Anti-Doping Agency Prohibited List as a PPARδ agonist within the hormone and metabolic modulators category. Sports organizations test for it because it has been detected in athlete samples and seized products. Regulatory actions against marketed research chemical versions have occurred in several countries, though enforcement varies. Availability through unregulated channels complicates oversight.
Analytical laboratories typically identify cardarine and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is a common matrix in anti-doping testing, while blood and tissue may be used in research settings. Detection windows depend on the assay, the sample matrix, and the compound's metabolism. Because cardarine is extensively metabolized, laboratories often target specific metabolites to improve sensitivity and confirmation. Reference standards are required for reliable quantification. Method validation includes checks for selectivity, linearity, and carryover.
== Alternatives == A variety of other calculations have been done based on similar parameters to determine the risk of mortality in acute liver failure. The Acute Physiology and Chronic Health Evaluation II (APACHE II) score has a comparable sensitivity to the King's College Criteria in determining prognosis.
=== Ionic crystal structures === In 1929, Pauling published five rules which help to predict and explain crystal structures of ionic compounds. These rules concern (1) the ratio of cation radius to anion radius, (2) the electrostatic bond strength, (3) the sharing of polyhedron corners, edges and faces, (4) crystals containing different cations, and (5) the rule of parsimony.
== Evolutionary history == It was found that pyruvate dehydrogenase enzyme found in the mitochondria of eukaryotic cells closely resembles an enzyme from Geobacillus stearothermophilus, which is a species of gram-positive bacteria. Despite similarities of the pyruvate dehydrogenase complex with gram-positive bacteria, there is little resemblance with those of gram-negative bacteria. Similarities of the quaternary structures between pyruvate dehydrogenase and enzymes in gram-positive bacteria point to a shared evolutionary history which is distinctive from the evolutionary history of corresponding enzymes found in gram-negative bacteria. Through an endosymbiotic event, pyruvate dehydrogenase found in the eukaryotic mitochondria points to ancestral linkages dating back to gram-positive bacteria. Pyruvate dehydrogenase complexes share many similarities with branched chain 2-oxoacid dehydrogenase (BCOADH), particularly in their substrate specificity for alpha-keto acids. Specifically, BCOADH catalyzes the degradation of amino acids and these enzymes would have been prevalent during the periods on prehistoric Earth dominated by rich amino acid environments. The E2 subunit from pyruvate dehydrogenase evolved from the E2 gene found in BCOADH while both enzymes contain identical E3 subunits due to the presence of only one E3 gene. Since the E1 subunits have a distinctive specificity for particular substrates, the E1 subunits of pyruvate dehydrogenase and BCOADH vary but share genetic similarities.
Sources: en.wikipedia.org
== Criticism == In a 2002 lawsuit against McDonald's, a judge commented that Chicken McNuggets are a "McFrankenstein" creation. The judge identified that rather than being merely chicken fried in a pan, McNuggets included elements not utilized by the home cook, including unusual sounding ingredients such as extracts of rosemary, vitamins (niacin, thiamine mononitrate, riboflavin, and folic acid) all of which are common in enriched flour, and leavening (baking soda, calcium lactate, etc.). The 2004 documentary Super Size Me states that "[o]riginally created from old chickens that can no longer lay eggs, McNuggets are now made from chickens with unusually large breasts. They're stripped from the bone, and ground-up into a sort of 'chicken mash', which is then combined with all sorts of stabilizers and preservatives, pressed into familiar shapes, breaded, deep-fried, freeze-dried, and then shipped to a McDonald's near you." Super Size Me also alleged inclusion of ingredients such as TBHQ, polydimethylsiloxane, and others not used by a typical home cook. This was subsequently restated by CNN. Marion Nestle, a New York University professor and author of What to Eat, says that the ingredients in McNuggets probably pose no health risks. Before August 2016, dimethylpolysiloxane and TBHQ were listed as ingredients in the McNuggets cooking process. According to Lisa McComb, a media relations representative for McDonald's, dimethylpolysiloxane is used as a matter of safety to keep the frying oil from foaming.
Hydrogen selenide is an extremely toxic, corrosive gas. Selenium also occurs in organic compounds, such as dimethyl selenide, selenomethionine, selenocysteine and methylselenocysteine, all of which have high bioavailability and are toxic in large doses. The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for selenium in the workplace at 0.2 mg/m3 over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 0.2 mg/m3 over an 8-hour workday. At levels of 1 mg/m3, selenium is immediately dangerous to life and health.
=== Generic names === Topilutamide is the generic name of the drug and its INNTooltip International Nonproprietary Name. It is also known more commonly as fluridil. Topilutamide is also known by its former developmental code name BP-766.
Historic England. "Bawdsey Chain Home Station (1309533)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "Great Bromley Chain Home Station (1476819)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "Canewdon Chain Home Station (1412472)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "Dunkirk Chain Home Station (1377189)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "High Street Chain Home Station (1476863)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "Pevensey Chain Home Station (1476551)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "Rye Chain Home Station (1476520)". Research records (formerly PastScape). Retrieved 9 October 2015. Historic England. "Ventnor Chain Home Station (1306901)". Research records (formerly PastScape). Retrieved 9 October 2015. Early Radar Memories Archived 2 September 2010 at the Wayback Machine Memories of Sgt. Jean Semple, one of Britain's pioneer radar operators RAF Bawdsey Chain Home Radar Station at Subterranean Britain RAF Radar Museum RAF High Street picture Life at Darsham Deprecated link archived 19 April 2013 at archive.today – BBC Great Baddow Chain Home Mast & Radar Anniversary Chain Home Radar – A Personal Reminiscence, M Scanlan, GEC Review, 1993 Early radar development in the UK at purbeckradar.co.uk 60 (Signals) Group, Fighter Command Archived 16 November 2017 at the Wayback Machine (pdf)
Sources: en.wikipedia.org
=== Criteria === Diabetic ketoacidosis is distinguished from other diabetic emergencies by the presence of large amounts of ketones in blood and urine, and marked metabolic acidosis. Hyperosmolar hyperglycemic state (HHS, sometimes labeled "hyperosmolar non-ketotic state" or HONK) is much more common in type 2 diabetes and features increased plasma osmolarity (above 320 mosm/kg) due to profound dehydration and concentration of the blood; mild acidosis and ketonemia may occur in this state, but not to the extent observed in DKA. There is a degree of overlap between DKA and HHS, as in DKA the osmolarity may also be increased. Ketoacidosis is not always the result of diabetes. It may also result from alcohol excess and from starvation; in both states the glucose level is normal or low. Metabolic acidosis may occur in people with diabetes for other reasons, such as poisoning with ethylene glycol or paraldehyde. The American Diabetes Association categorizes DKA in adults into one of three stages of severity:
=== Deficiency === Decreased AVP release (neurogenic — i.e. due to alcohol intoxication or tumour) or decreased renal sensitivity to AVP (nephrogenic, i.e. by mutation of V2 receptor or AQP) leads to diabetes insipidus, a condition featuring hypernatremia (increased blood sodium concentration), polyuria (excess urine production), and polydipsia (thirst).
==== Stability ==== A disadvantage of using nanocrystals for drug delivery is nanocrystal stability. Instability problems of nanocrystalline structures derive from thermodynamic processes such as particle aggregation, amorphization, and bulk crystallization. Particles at the nanoscopic scale feature a relative excess of Gibbs free energy, due to their higher surface area to volume ratio. To reduce this excess energy, it is generally favorable for aggregation to occur. Thus, individual nanocrystals are relatively unstable by themselves and will generally aggregate. This is particularly problematic in top-down production of nanocrystals. Methods such as high-pressure homogenization and bead milling, tend to increase instabilities by increasing surface areas; to compensate, or as a response to high pressure, individual particles may aggregate or turn amorphous in structure. Such methods can also lead to the reprecipitation of the drug by surpassing the solubility beyond the saturation point (Ostwald ripening). One method to overcome aggregation and retain or increase nanocrystal stability is by use of stabilizer molecules. These molecules, which interact with the surface of the nanocrystals and prevent aggregation via ionic repulsion or steric barriers between the individual nanocrystals, include surfactants and are generally useful for stabilizing suspensions of nanocrystals. Concentrations of surfactants that are too high, however, may inhibit nanocrystal stability and enhance crystal growth or aggregation.
== External links == Glycoproteins at the U.S. National Library of Medicine Medical Subject Headings (MeSH) "Biological Importance of the glycosylation of a protein". BiochemPages. 15 August 2015. Archived from the original on 30 November 2020. Retrieved 18 August 2015. "Carbohydrate Chemistry and Glycobiology: A Web Tour". Science. 291 (5512): 2263–2502. 23 March 2001. Archived from the original on 9 January 2008. Special Web Supplement "Glycan Recognizing Proteins". bioWORLD. "Structure of Glycoprotein and Carbohydrate Chain". Home Page for Learning Environmental Chemistry.
== Side effects and risks == Risks of an improperly performed dermal filler procedure commonly include bruising, redness, pain, or itching. Less commonly, there may be infections or allergic reactions, which may cause scarring and lumps that may require surgical correction. In 2024, a cluster of HIV infections was described amongst clients receiving microneedling facials at a spa. More rarely, serious adverse effects such as blindness due to retrograde (opposite the direction of normal blood flow) embolization into the ophthalmic and retinal arteries can occur. Delayed skin necrosis can also occur as a complication of embolization. Embolic complications are more frequently seen when autologous fat is used as a filler, followed by hyaluronic acid. Though rare, when vision loss does occur, it is usually permanent.
Sources: en.wikipedia.org
Cardarine is a common name for the investigational compound GW501516. It acts as a PPARδ agonist and is not approved for human use. It is prohibited in sport.
It activates PPARδ, a nuclear receptor that influences gene expression related to lipid and energy metabolism. Animal studies show changes in endurance and lipid levels. Human effects and risks are not well established.
No, cardarine is not a steroid. It belongs to a different chemical class, the PPARδ agonists. It is also not a selective androgen receptor modulator.
Anti-doping laboratories typically use LC-MS/MS to detect GW501516 and its metabolites in urine. The method is sensitive and can identify the compound at low concentrations. Detection depends on sample timing, metabolism, and the specific assay.