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Background And Regulatory History — Questions and Answers

By Editorial Desk · published 2026-04-23 · last reviewed 2026-05-11 · Faq

A practical reference on PPARδ: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.

This page was last updated on 2026-05-11 and is reviewed periodically as new material appears.

Background and Regulatory History

GW501516 acts on PPARδ, a nuclear receptor that helps regulate fatty acid oxidation and energy homeostasis. In animal studies, activation of this receptor was associated with increased endurance and changes in lipid metabolism. Human trials examined effects on blood lipids and other metabolic markers, but the compound did not advance to approval. Rodent studies later reported tumors in multiple tissues at doses used in those experiments. Whether those findings translate to human risk remains uncertain, and the clinical relevance of the animal data is still debated.

Regulatory bodies treat GW501516 as a prohibited substance in competitive sport. The World Anti-Doping Agency added it to the prohibited list, and it falls under classes covering metabolic modulators and hormone-related agents. It is not approved by drug regulators for human use, and it is not a lawful dietary supplement. Products sold under the cardarine name may contain unlisted ingredients or different compounds. Because no approved product exists, quality and identity are not guaranteed by pharmaceutical manufacturing standards.

Mechanism and Laboratory Detection

GW501516 binds and activates PPARδ, a nuclear receptor that influences transcription of genes involved in fatty acid oxidation and energy use. Activation shifts some metabolic pathways in preclinical models, which is why the compound has been studied for lipid disorders and exercise-related endpoints. The exact downstream effects in humans are incompletely mapped. PPARδ is expressed in many tissues, including skeletal muscle, liver, and adipose tissue, so broad activation may have varied consequences. Researchers continue to examine how selective or partial activation might alter the balance between benefits and risks.

Published human data are sparse and mostly come from early-phase trials. Those studies examined short-term changes in lipids, glucose, and exercise capacity, but they were not large enough to establish efficacy or long-term safety. Some animal experiments reported increased running endurance, yet such findings do not prove a performance benefit in people. Anti-doping laboratories detect GW501516 and its metabolites in urine or blood using liquid chromatography-tandem mass spectrometry. Detection windows depend on dose, sample type, and individual metabolism. The method is sensitive enough to identify trace residues in tested samples.

Cardarine at a glance

PropertyValueNotes
Common nameCardarineCommon internet and media name.
Research codeGW501516Also written GW-1516.
Drug classPPARδ agonistNot a selective androgen receptor modulator.
Development statusDiscontinuedClinical development halted after rodent cancer findings.
Regulatory statusProhibited in sportListed by WADA; not approved as medicine.

Regulation and Analytical Detection

Cardarine is prohibited in competitive sport under the World Anti-Doping Agency code, where it is classified as a metabolic modulator. It is not approved as a prescription medicine in the United States, European Union, or other major markets. Regulatory action has focused on its presence in sports and in products marketed as research chemicals. Because it has no accepted medical indication, supply is often unregulated. This status creates legal and safety uncertainties for anyone who encounters the substance.

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.

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Mechanism and Detection Methods

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.

Identity and Pharmacological Classification

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.

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.

Notes from published material

=== US bases === In legal analysis of the crisis, some commentators suggested sovereign bases as a solution, similar to the United Kingdom's retention of sovereign base areas in Cyprus, under which limited territory is held under foreign sovereignty primarily for military purposes. Commentators suggested that such a model could allow a foreign power to exercise sovereign control over specific installations in Greenland without a broader transfer of territory, though the proposal was described as legally complex and politically contentious. Danish MP Sascha Faxe said giving up any sovereignty is completely out of the question, specifically stating that the Cyprus situation is not an option, whilst emphasising that military bases already have a significant degree of operational autonomy and jurisdiction under existing agreements, in line with what is normal for US bases abroad. Both Danish and Greenland officials said sovereignty is not negotiable. On 26 January, Greenland's government said the idea of transferring "sovereignty" of any Greenlandic land, including bases, is not possible and described it as a "red line."

Many different studies have been conducted on the sensory changes that occur in wines that have gone through malolactic fermentation. The most common descriptor is that acidity in the wine feels "softer" due to the change of the "harsher" malic acid to the softer lactic acid. The perception of sourness comes from the titratable acidity in the wine, so the reduction in TA that follows MLF leads to a reduction in perceived sour or "tartness" in the wine. The change in mouthfeel is related to the increase in pH, but may also be due to the production of polyols, particularly the sugar alcohols erythritol and glycerol. Another factor that may enhance the mouthfeel of wines that have gone through malolactic fermentation is the presence of ethyl lactate which can be as high as 110 mg/L after MLF. The potential influence on the aroma of the wine is more complex and difficult to predict with different strains of Oenococcus oeni (the bacterium most commonly used in MLF) having the potential to create different aroma compounds. In Chardonnay, wines that have gone through MLF are often described as having "hazelnut" and "dried fruit" notes, as well as the aroma of freshly baked bread. In red wines, some strains metabolize the amino acid methionine into a derivative of propionic acid that tends to produce roasted aroma and chocolate notes. Red wines that go through malolactic fermentation in the barrel can have enhanced spice or smoke aromas.

=== DNA damage and cellular stress === CK1δ can be also activated by genotoxic stress and DNA damage in a p53-dependent manner, and phosphorylate key regulatory proteins in response to these processes. CK1δ phosphorylates human p53 on Ser-6, Ser-9, and Ser-20. Moreover, CK1δ phosphorylates p53 on Thr-18, once p53 is already phospho-primed, permitting a lower p53-Mdm2 binding and higher p53 activity. Under normal conditions, CK1δ can phosphorylate Mdm2 on Ser-240, Ser-242, Ser-246, and Ser-383, permitting higher p53-Mdm2 stability and further p53 degradation. On the contrary, after DNA damage, ATM phosphorylates CK1δ, which can subsequently phosphorylate Mdm2 inducing its proteasomal degradation. Under hypoxia, CK1δ is involved in reducing cell proliferation by interfering with HIF-1α/ARNT complex formation. Additionally, the activity of topoisomerase II α (TOPOII-α), one of the main regulators of DNA replication, results increased after its CK1δ-mediated phosphorylation on Ser-1106. Under stress conditions, CK1δ can interfere with DNA replication. In fact, CK1δ phosphorylates a main regulator of DNA methylation, the ubiquitin-like containing PHD and RING finger domains 1 protein (UHRF1), on Ser-108, increasing its proteasomal degradation.

Sources: en.wikipedia.org

Background from the literature

== Doubts about existence == In October 2011 the Journal of Strategic Studies, a leading journal in that field, published an article by Thomas Rid, "Cyber War Will Not Take Place" which argued that all politically motivated cyber attacks are merely sophisticated versions of sabotage, espionage, or subversion – and that it is unlikely that cyber war will occur in the future.

=== Al–Am === Bruce Alberts (b. 1938). American biochemist at UC San Francisco, known for his work on protein complexes that enable chromosome replication in science, public policy, and as an original author of the textbook Molecular Biology of the Cell. Member Natl. Acad. Sci. USA. Robert Alberty (1921–2014). American physical biochemist at MIT, noted for many contributions to enzyme kinetics, including early studies of reactions with two substrates. Member Natl. Acad. Sci. USA. Dario Alessi (b. 1967). British biochemist at the University of Dundee known for work on protein kinases. Mary Belle Allen (1922–1973). American botanist at UC Berkeley known for demonstrating the role of chloroplasts in photosynthesis. Jorge Allende (b. 1934). Chilean biochemist at the University of Chile, known for contributions to the understanding of protein biosynthesis and how transfer RNA is generated. Member Natl. Acad. Sci. USA. C. David Allis (1951–2023), US biologist at the Rockefeller University who worked on chromatin. Richard Amasino (b. 1956). American Professor of Biochemistry and Genetics at the University of Wisconsin–Madison, who studies vernalization. Member Natl. Acad. Sci. USA. Bruce Ames (1928–2024). Biochemist and microbiologist at UC Berkeley. He is an expert on mutagenicity and an inventor of the Ames test. Awarded the National Medal of Science John E. Amoore (1939–1998). British biochemist and zoologist at UC Berkeley, who postulated the stereochemical theory of olfaction.

When reporting on the masses of extrasolar planets, astronomers often discuss them in terms of multiples of Jupiter's mass (MJ = 1.9 ×1027 kg). For example, "Astronomers recently discovered a planet outside our Solar System with a mass of approximately 3 Jupiters." Furthermore, the mass of Jupiter is nearly equal to one thousandth of the mass of the Sun.

Sources: en.wikipedia.org

Further detail

== Function == In many organs like liver, lung, and kidneys, they are primarily involved in fibrosis. In the wound tissue they are implicated in wound strengthening by extracellular collagen fiber deposition and then wound contraction by intracellular contraction and concomitant alignment of the collagen fibers by integrin-mediated pulling on to the collagen bundles. Pericytes and renal mesangial cells are some examples of modified myofibroblast-like cells. Myofibroblasts may interfere with the propagation of electrical signals controlling heart rhythm, leading to arrhythmia in both patients who have suffered a heart attack and in foetuses. Ursodiol is a promising drug for this condition.

Retailing in India is a pillar of the national economy accounting for about 10 percent of GDP. The Indian retail market is estimated to be worth $1.3 trillion as of 2022. India is one of the fastest growing retail markets in the world, with 1.4 billion people. As of 2003, India's retailing industry was essentially owner staffed small shops. In 2010, larger format convenience stores and supermarkets accounted for about 4 percent of the industry, and these were present only in large urban centers. India's retail and logistics industry employs about 40 million Indians (3.3% of Indian population). In November 2011, India's central government announced retail reforms for both multi-brand stores and single-brand stores. These market reforms paved the way for retail innovation and competition with multi-brand retailers such as Walmart, Carrefour and Tesco, as well single brand majors such as IKEA, Nike, and Apple. The announcement sparked intense activism, both in opposition and in support of the reforms. In December 2011, under pressure from the opposition, Indian government placed the retail reforms on hold until a consensus was reached. In January 2012, India approved reforms for single-brand stores welcoming anyone in the world to innovate in Indian retail market with 100% ownership, but imposed the requirement that the single brand retailer source 30 percent of its goods from India. Indian government continues the hold on retail reforms for multi-brand stores.

Belize's tourism is strongly supported by natural assets, including the Belize Barrier reef, offshore cays, and extensive opportunities for boating, scuba diving, snorkeling, freediving and kayaking. The country offers jungle and wildlife reserves suited for hiking, birdwatching, helicopter touring and visits to Maya archeological sites. Development costs are high, but the government of Belize has made tourism its second development priority after agriculture. In 2012, tourist arrivals totalled 917,869 (with about 584,683 from the United States) and tourist receipts amounted to over $1.3 billion. After COVID-19 struck tourism, Belize became the first country in the Caribbean to allow vaccinated travellers to visit without a COVID-19 test. Since 2023 The tourism is growing with 2024 having 1.4 million visitors. In 2024 Belize had around 430 thousand overnight tourists. Tourism contains about 43% of Belize's export earnings and 17% of the GDP. Tourism creates about 20 thousand direct jobs and more than 30 thousand indirect jobs.

Treponema pallidum, formerly known as Spirochaeta pallida, is a microaerophilic, gram-negative, spirochaete bacterium with subspecies that cause the diseases syphilis, bejel (also known as endemic syphilis), and yaws. It is known to be transmitted only among humans and baboons. T. pallidum can enter the host through mucosal membranes or open lesions in the skin and is primarily spread through sexual contact. It is a helically coiled microorganism usually 6–15 μm long and 0.1–0.2 μm wide. T. pallidum's lack of both a tricarboxylic acid cycle and processes for oxidative phosphorylation results in minimal metabolic activity. As a chemoorganoheterotroph, Treponema pallidum is an obligate parasite that acquires its glucose carbon source from its host. Glucose can be used not only as a primary carbon source but also in glycolytic mechanisms to generate ATP needed to power the bacterium given its minimal genome. The treponemes have cytoplasmic and outer membranes. Using light microscopy, treponemes are visible only by using dark-field illumination. T. pallidum consists of three subspecies, T. p. pallidum, T. p. endemicum, and T. p. pertenue, each of which has a distinct related disorder. The ability of T. pallidum to avoid host immune defenses has allowed for stealth pathogenicity. The unique outer membrane structure and minimal expression of surface proteins of T. pallidum has made vaccine development difficult. Treponema pallidum can be treated with high efficacy by antibiotics that inhibit bacterial cell wall synthesis such as the beta-lactam antimicrobial penicillin-G.

Sources: en.wikipedia.org

Frequently asked questions

Is cardarine a selective androgen receptor modulator?

No. Cardarine is a PPARδ agonist, while selective androgen receptor modulators act on androgen receptors. The two classes differ in receptor target and downstream effects.

Why did clinical development stop?

Preclinical rodent studies reported cancers, including liver and bladder tumors, at tested doses. The human relevance of those findings is uncertain, but development was discontinued. No approved human product resulted.

Is cardarine approved for medical use?

No. It remains an investigational compound without approved therapeutic labeling. Sports regulators prohibit its use, and health agencies have warned against consuming it.

How is cardarine detected in samples?

Anti-doping and clinical laboratories commonly use liquid chromatography-tandem mass spectrometry. The method can identify GW501516 and its metabolites in urine or blood. Detection depends on sample timing and the amount present.

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