Nuclear receptor comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-11-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Laboratory detection of GW501516 commonly uses liquid chromatography coupled with tandem mass spectrometry. The method can identify the parent compound or its metabolites in urine and blood after sample cleanup. Protein precipitation, solid-phase extraction, or enzymatic hydrolysis may precede analysis, depending on the matrix. Reference standards are required for accurate quantification and confirmation. Because the compound is not approved, testing often occurs in anti-doping, forensic, or research settings rather than routine clinical care. Results are reported with limits of detection and quantification.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Prohibited in sport | Listed by WADA as a PPARδ agonist. |
| Typical detection matrix | Urine | Most common sample for anti-doping analysis. |
| Common analytical method | LC-MS/MS | Liquid chromatography-tandem mass spectrometry. |
| Common synonyms | GW501516, GSK-516, endurobol | Names found in research and fitness contexts. |
| Typical detection window | Variable | Depends on dose, route, and individual metabolism. |
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.
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.
Regulatory treatment varies, but cardarine is not approved as a medicine. Sports authorities list GW501516 as a prohibited substance, and it is banned at all times under the World Anti-Doping Agency code. Many countries restrict sales for human consumption, while online vendors market it as a research chemical. Such products may lack purity data, and their actual contents can differ from the label. Purchasing or possessing cardarine may carry legal consequences depending on jurisdiction. The compound is not a dietary supplement ingredient in regulated markets.
Clinical development stopped after rodent studies showed tumors at multiple sites. Whether those findings predict human cancer risk remains an open question, but they led sponsors to discontinue programs. Human safety data are limited to small, short-term studies that were not designed to assess cancer risk. Reported effects in those studies included changes in blood lipids, but the evidence is insufficient for medical use. Long-term consequences of nonmedical use are not well characterized. Questions about dose, duration, and individual susceptibility remain unresolved.
Cardarine is a common name for GW501516, an investigational compound developed in the 1990s for metabolic conditions. It acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in lipid and energy metabolism. The compound is frequently mislabeled as a selective androgen receptor modulator, or SARM, but its molecular target is different. GW501516 reached early clinical testing before development was discontinued. It has no approved therapeutic use in any country. The name cardarine is not a formal international nonproprietary name.
Cardarine is a common name for GW501516, a synthetic compound studied for its effects on lipid and glucose metabolism. It functions as an agonist at peroxisome proliferator-activated receptor delta, or PPARδ, a nuclear receptor that influences gene expression. The molecule is not a steroid, nor is it a selective androgen receptor modulator. It is also known in research and sports literature as GW-501516 and endurobol. Early laboratory work examined its metabolic activity in cell cultures and animal models.
Activation of PPARδ changes transcription of genes involved in fatty acid transport, mitochondrial function, and skeletal muscle fuel preference. In rodent studies, pharmacological PPARδ activation was associated with increased endurance and altered body composition. These findings generated interest in performance enhancement, but species differences and study designs limit direct extrapolation to humans. Small human trials were conducted in the 2000s and later discontinued. The extent to which cardarine produces similar metabolic or performance effects in people remains an open question.
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.
Strychnine is a terpene indole alkaloid belonging to the Strychnos family of Corynanthe alkaloids, and it is derived from tryptamine and secologanin. The biosynthesis of strychnine was solved in 2022. The enzyme, strictosidine synthase, catalyzes the condensation of tryptamine and secologanin, followed by a Pictet-Spengler reaction to form strictosidine. Many steps have been inferred by isolation of intermediates from Strychnos nux-vomica. The next step is hydrolysis of the acetal, which opens the ring by elimination of glucose (O-Glu) and provides a reactive aldehyde. The nascent aldehyde is then attacked by a secondary amine to afford geissoschizine, a common intermediate of many related compounds in the Strychnos family. A reverse Pictet-Spengler reaction cleaves the C2–C3 bond, while subsequently forming the C3–C7 bond via a 1,2-alkyl migration, an oxidation from a Cytochrome P450 enzyme to a spiro-oxindole, nucleophilic attack from the enol at C16, and elimination of oxygen forms the C2–C16 bond to provide dehydropreakuammicine. Hydrolysis of the methyl ester and decarboxylation leads to norfluorocurarine. Stereospecific reduction of the endocyclic double bond by NADPH and hydroxylation provides the Wieland-Gumlich aldehyde, which was first isolated by Heimberger and Scott in 1973, although previously synthesized by Wieland and Gumlich in 1932. To elongate the appendage by two carbons, acetyl-CoA is added to the aldehyde in an aldol reaction to afford prestrychnine.
== Scientific work and contributions == Richardson's first forays into science were in the field of astronomy. By observing the position of Sputnik – at the time, the only artificial satellite – on two successive nights, she managed to calculate its predicted orbit. She submitted her results to the Westinghouse Science Talent Search, winning third place in 1958. Richardson joined her husband David C. Richardson, then completing his PhD work at MIT, in studying the 3-dimensional structure of the staphylococcal nuclease protein (1SNS) by X-ray crystallography for his doctoral thesis. Staphylococcal nuclease was among the first dozen protein structures solved. Classes in botany and evolution that she had taken while pursuing her degree shaped her thinking about the work she was doing in the chemistry laboratory. During her crystallographic studies, Jane Richardson had come to realize that a general classification scheme can be developed from the recurring structural motifs of the proteins. In the meantime, Jane and David Richardson had moved to Duke University in 1970, where they solved the first crystal structure of superoxide dismutase (2SOD). By 1977 she published her findings on protein relatedness in Nature, with a paper entitled "β-sheet topology and the relatedness of proteins".
== Chemistry == Pseudoephedrine, also known structurally as (1S,2S)-α,N-dimethyl-β-hydroxyphenethylamine or as (1S,2S)-N-methyl-β-hydroxyamphetamine, is a substituted phenethylamine, amphetamine, and β-hydroxyamphetamine derivative. It is a diastereomer of ephedrine. Pseudoephedrine is a small-molecule compound with the molecular formula C10H15NO and a molecular weight of 165.23 g/mol. It has an experimental log P of 0.89, while its predicted log P values range from 0.9 to 1.32. The compound is relatively lipophilic, but is also more hydrophilic than other amphetamines. The lipophilicity of amphetamines is closely related to their brain permeability. For comparison to pseudoephedrine, the experimental log P of methamphetamine is 2.1, of amphetamine is 1.8, of ephedrine is 1.1, of phenylpropanolamine is 0.7, of phenylephrine is -0.3, and of norepinephrine is -1.2. Methamphetamine has high brain permeability, whereas phenylephrine and norepinephrine are peripherally selective drugs. The optimal log P for brain permeation and central activity is about 2.1 (range 1.5–2.7). Pseudoephedrine is readily reduced into methamphetamine or oxidized into methcathinone.
=== Acute effects === The median lethal dose (LD50) for acute radiation exposure is about 4.5 Sieverts (Sv). The committed effective dose equivalent 210Po is 0.51 μSv/Becquerel (Bq) if ingested, and 2.5 μSv/Bq if inhaled. A fatal 4.5 Sv dose can be caused by ingesting 8.8 MBq (240 μCi), about 50 nanograms (ng), or inhaling 1.8 MBq (49 μCi), about 10 ng. One gram of 210Po could thus in theory poison 20 million people, of whom 10 million would die. The actual toxicity of 210Po is lower than these estimates because radiation exposure that is spread out over several weeks (the biological half-life of polonium in humans is 30 to 50 days) is less damaging than an instantaneous dose. It has been estimated that a median lethal dose of 210Po is 15 megabecquerels (0.41 mCi), or 0.89 micrograms (μg). For comparison, one grain of table salt is about 0.06 mg = 60 μg.
Adolescents experiencing gender dysphoria may opt to undergo puberty-suppressing hormone therapy at the onset of puberty. The Standards of Care set forth by WPATH recommend individuals pursuing puberty-suppressing hormone therapy wait until at least experiencing Tanner Stage 2 pubertal development. Tanner Stage 2 is defined by the appearance of scant pubic hair, breast bud development, and/or slight testicular growth. WPATH classifies puberty-suppressing hormone therapy as a "fully reversible" intervention. Delaying puberty allows individuals more time to explore their gender identity before deciding on more permanent interventions and prevents the physical changes associated with puberty. The preferred puberty-suppressing agent for both individuals assigned male at birth and individuals assigned female at birth is a GnRH Analogue. This approach temporarily shuts down the Hypothalamic-Pituitary-Gonadal (HPG) Axis, which is responsible for the production of hormones (estrogen, testosterone) that cause the development of secondary sexual characteristics in puberty. According to a study by JAMA Pediatrics published in January 2025, less than 0.1% of adolescents covered by private medical insurance in the US take gender-affirming medication to treat gender dysphoria.
Sources: en.wikipedia.org
== Legacy and later life == Singh's structured administration is credited with slowing India's rate of deforestation between 1960 and 1980 by introducing professional oversight and improving legal frameworks against illegal logging. After retiring from the civil service in 1969, he served as a Professor Emeritus at the Forest Research Institute and College for a five-year term, and later as the Managing Director of the Newsprint Paper and Pulp Mills in Nepanagar, Madhya Pradesh. His contributions were commemorated during his birth centenary in 2010 with the release of a biographical book, Hari Singh: A Life Sketch, and the establishment of the Hari Singh Fellowship at the Indira Gandhi National Forest Academy to honour outstanding IFS probationers. Singh was married and had at least one son, Dr. Subir Hari Singh. He passed away in 2003 at the age of 93.
=== Potential risks === As BLCO contains materials like vanadium, nickel and PAH, those tend to be harmful and disturb possibility of antioxidant. Heavy metals are necessary in metabolic process of creatures; however, they are the causes of physiological stress at the same time. Pollution problems by oil spills like soils contamination are continuous and prevalent, putting severe health and environmental threats. The pollutants can gradually accumulate in food chains and interrupt biological actions of creatures. Petroleum contaminants are pernicious to nature and moreover, their hydrocarbon elements which are mutagenic and causing cancers, entail immunomodulatory impacts on humans and organisms as well. The symptoms of risks can appear immediately or emerge after some time.
In the evening in Beijing, Trump arrived at Beijing Capital International Airport, where he was greeted by Chinese vice president Han Zheng, Chinese Ambassador to the US Xie Feng, Executive Vice Foreign Minister Ma Zhaoxu, and US Ambassador to China David Perdue, as well as a military honor guard, a military band and around 300 Chinese students waving Chinese and American flags. Trump and his entourage then boarded a motorcade, which later arrived at the Four Seasons Beijing Hotel, while other members of the delegation would stay at the Kempinski Hotel Beijing Yansha Center.
=== Affinity proteomics === Affinity proteomics is a high-throughput method of studying the proteome with antibody or other affinity reagents (e.g. aptamers). Large numbers (dozens to hundreds) of immune-related cytokines and related markers can be simultaneously assayed in solution, in contrast to a solid substrate such as a microarray.
Reflecting on the band's hiatus in a 2011 interview, Kinney said that Staley wasn't the only one battling addiction. He was the focal point, like singers are. So they'd single him out. But the truth was, it was pretty much everybody. I definitely had my hand firmly on the wheel going off the cliff. And the reason we pulled back – you know when you stop when you have two No. 1 records, it's not really the greatest career move – but we did that because we love each other and we didn't want to die in public. And I know for a fact in my heart that if we were to continue that I wouldn't be on the phone right now talking to you. I wouldn't have made it. I just wouldn't have. After a decade of battling drug addiction, Layne Staley was found dead in his condominium on April 19, 2002. The autopsy and toxicology report revealed that he died from a mixture of heroin and cocaine, known as "speedball". The autopsy concluded that Staley died on April 5, two weeks before his body was found. Cantrell dedicated his 2002 solo album, Degradation Trip, released two months after Staley's death, to his memory. Mike Starr later claimed on Celebrity Rehab that he was the last person to see Staley alive, and admitted to feeling guilty about not calling 911 after Staley had warned him against it. "I wish I hadn't been high on benzodiazepine [that night], I wouldn't have just walked out the door," Starr said. Following Staley's death, Mike Inez joined Heart and toured and recorded with the band from 2002 through 2006.
Sources: en.wikipedia.org
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.
Detection usually uses liquid chromatography-tandem mass spectrometry after sample cleanup. Laboratories look for the parent compound or metabolites. The method requires validated reference standards and controls.
Legality varies by country. In many places it is an unapproved drug and cannot be legally sold for human consumption. Purchasing from online vendors carries legal and quality risks.
LC-MS/MS is common, often after sample cleanup. The assay targets GW501516 or its metabolites.