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Background And Regulatory History — 2026 Update

By Editorial Desk · published 2025-08-26 · last reviewed 2025-09-15 · Info

GW501516 is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.

Updated 2025-09-15. Numbers and descriptions here follow the published literature rather than marketing material.

Background and Regulatory History

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.

Cardarine is a common name for the investigational chemical GW501516, also written GW-1516. It was developed as a peroxisome proliferator-activated receptor delta agonist for metabolic conditions such as dyslipidemia. Early research focused on lipid handling and energy use in skeletal muscle and other tissues. The compound was never approved as a medicine. In public discussion, it is often grouped with performance-enhancing substances, although its receptor target differs from that of anabolic steroids or selective androgen receptor modulators. Regulatory and health authorities have issued warnings about its use.

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.

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.

Cardarine as Investigational PPARδ Agonist

The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.

Safety discussions about cardarine frequently cite rodent carcinogenicity findings reported in the 2000s. In those studies, treated animals developed tumors at multiple sites, leading sponsors to discontinue clinical development. The relevance of these findings to humans has not been resolved, but they are a major reason the compound is not approved. Current literature emphasizes uncertainty about long-term effects and the risks of unregulated use. Regulators and health agencies have not established a safe human exposure level.

Cardarine is a synthetic compound also known as GW501516, GW-501516, and sometimes endurobol. It was developed as a selective agonist of peroxisome proliferator-activated receptor delta, a nuclear receptor involved in fatty acid oxidation and energy metabolism. The compound was studied in preclinical models for metabolic and cardiovascular conditions, but it did not become a marketed human medicine. In regulatory and anti-doping contexts, it is treated as a prohibited substance rather than a licensed medicine.

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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.

Regulation and Detection

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.

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.

Notes from published material

The government of Santiago Peña began on 15 August 2023 following his election as President of Paraguay. He was sworn in as president at the age of 44, becoming the youngest president of Paraguay since the restoration of democracy in 1989, surpassing Mario Abdo Benítez, who was 46 years old at the time of his inauguration. In the first days of his term, administrative reforms aimed at the reorganization of the executive branch and the centralization of state functions were promoted. One of the main changes was the creation of the Ministry of Economy and Finance, enacted on 23 August 2023. This new ministry absorbed the functions of the defunct Ministry of Finance, the Technical Secretariat for Economic and Social Development Planning (STP), and the Secretariat of the Civil Service (SFP). Carlos Fernández Valdovinos was appointed as the first minister of this institution. Likewise, the National Directorate of Tax Revenue (DNIT) was established through the merger of the Undersecretariat of State for Taxation (SET) and the National Customs Directorate (DNA). As for the binational entities and other key institutions, Justo Zacarías Irún was appointed acting general director of Itaipu Binacional, while Luis Federico Benítez Cuevas assumed office as acting director of the Yacyretá Binational Entity (EBY). At the National Development Bank (BNF), the presidency was assigned to Manuel Ochipinti. For her part, Liliana Alcaraz was appointed minister of the Secretariat for the Prevention of Money or Asset Laundering (Seprelad).

=== Cryoprobe === Cryoneurolysis is performed with a cryoprobe, which is composed of a hollow cannula that contains a smaller inner lumen. The pressurized coolant (nitrous oxide, carbon dioxide or liquid nitrogen) travels down the lumen and expands at the end of the lumen into the tip of the hollow cannula. No coolant exits the cryoprobe. The expansion of the pressurized liquid causes the surrounding area to cool (known as the Joule–Thomson effect) and the phase change of the liquid to gas also causes the surrounding area to cool. This causes a visible iceball to form and the tissue surrounding the end of the cryoprobe to freeze. The gas form of the coolant then travels up the length of the cryoprobe and is safely expelled. The tissue surrounding the end of the cryoprobe can reach as low as −88.5 °C with nitrous oxide as the coolant, and as low as −195.8 °C with liquid nitrogen. Temperatures below −100 °C are damaging to nerves.

In very general terms, the viscous stresses in a fluid are defined as those resulting from the relative velocity of different fluid particles. As such, the viscous stresses must depend on spatial gradients of the flow velocity. If the velocity gradients are small, then to a first approximation the viscous stresses depend only on the first derivatives of the velocity. (For Newtonian fluids, this is also a linear dependence.) In Cartesian coordinates, the general relationship can then be written as

Van Buren (1829), member of New York State Assembly Henry Ledyard (1830), mayor of Detroit; president of Newport Hospital Henry Nicoll (1830), U.S. congressman from New York Henry C. Murphy (1830), U.S. congressman from New York; former U.S. ambassador to the Netherlands John L. O'Sullivan (1831), US minister to Portugal; journalist who coined the term " Manifest Destiny"; publisher of The United States Magazine and Democratic Review James William Beekman (1834), member of the New York State Senate; vice-president of the New York Hospital Isaac C. Delaplaine (1834), U.S. congressman from New York John Richardson Thurman (1835), U.S. congressman from New York John Jay (1836), grandson of Chief Justice John Jay; United States minister to Austro-Hungary; president of the American Historical Association John Vanderbilt (1837), judge, member of the New York State Senate William Ward Duffield (1841), officer, member of the Michigan Senate, superintendent of the U.S. National Geodetic Survey Abram Stevens Hewitt (1842), former mayor of New York City and planner of the first line of the New York City Subway system; Chairman of the Democratic National Committee 1876–1877, son-in-law of philanthropist Peter Cooper Edward Cooper (1842), former mayor of New York City and son of industrialist Peter Cooper Nicholas B. La Bau (1844), member of the New York State Assembly and the New York State Senate John Winthrop Chanler (1847), U.S. congressman from New York Horace Carpentier (1848), first mayor of Oakland, California and president of the Overland Telegraph Company A.

== History == In the United States, the profession began in the 1950s due to a shortage of medical technologists in rural areas and physician owned laboratories. MLA positions were more prevalent prior to laboratory automation, but have made a comeback due to the ongoing laboratory staffing shortage.

Sources: en.wikipedia.org

Background from the literature

== Uses == TCFH itself is a common reagent used in the preparation of uronium and guanidinium salts used for amide bond formation and peptide synthesis, such as HATU. Amide bond formation with TCFH can be performed in a wide range of organic solvents, most commonly acetonitrile, but also water and in the solid state. Reactions typically require an added Brønsted base, and a wide range can be employed including N,N-diisopropylethylamine (DIPEA). In reactions of carboxylic acids with TCFH and a weakly Lewis basic amine like DIPEA, formation of an acid chloride or anhydride as the active acylating agent occurs. Use of N-methylimidazole (NMI) as a base, with both Brønsted and Lewis basic properties, provides some unique advantages. Reactions of carboxylic acids with TCFH and a strongly Lewis basic amine like NMI lead to in situ formation of an N-acyl imidazolium ion (NAI) as the active acylating agent.

The University of Edinburgh Lecture Dr Stephen Brusatte – Tyrannosaur Discoveries Feb 20, 2015 28 species in the tyrannosaur family tree, when and where they lived Stephen Brusatte Thomas Carr 2016 Australia's answer to T-Rex, State Library of Queensland American Museum of Natural History

Photoaging or photoageing (also known as "dermatoheliosis") is a term used for the characteristic changes to skin induced by chronic UVA and UVB exposure. Clinically, photoaged skin commonly presents with wrinkles and pigmentary changes. Other features may include skin laxity, roughness, telangiectasia, solar lentigines, actinic keratoses, and skin cancers. Mechanisms involved in photoaging include ultraviolet-radiation-induced oxidative stress, DNA damage, and matrix metalloproteinase activity that contributes to degradation of extracellular matrix proteins such as collagen and elastin. Prevention focuses on photoprotection, including shade, sun-protective clothing, and sunscreen, while treatments discussed in dermatology literature include topical retinoids and procedural interventions.

The element was named after Marie Curie and her husband Pierre Curie, who are known for discovering radium and for their work in radioactivity. It followed the example of gadolinium, a lanthanide element above curium in the periodic table, which was named after the explorer of rare-earth elements Johan Gadolin:

Sources: en.wikipedia.org

Reference notes

Around late November to early December, Liu Xiang's forces made plans to assault Renshou and Jianyang, both on the approaches to Chengdu. Several sources cite December as the end date of the Two-Liu War; however, fighting continued long into 1933.

Different countries have different regulatory requirements and enforcement abilities. An estimated 40% of all clinical trials now take place in Asia, Eastern Europe, and Central and South America. "There is no compulsory registration system for clinical trials in these countries and many do not follow European directives in their operations", says Jacob Sijtsma of the Netherlands-based WEMOS, an advocacy health organisation tracking clinical trials in developing countries. Beginning in the 1980s, harmonization of clinical trial protocols was shown as feasible across countries of the European Union. At the same time, coordination between Europe, Japan and the United States led to a joint regulatory-industry initiative on international harmonization named after 1990 as the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) Currently, most clinical trial programs follow ICH guidelines, aimed at "ensuring that good quality, safe and effective medicines are developed and registered in the most efficient and cost-effective manner. These activities are pursued in the interest of the consumer and public health, to prevent unnecessary duplication of clinical trials in humans and to minimize the use of animal testing without compromising the regulatory obligations of safety and effectiveness."

==== Elimination ==== Tiagabine is excreted about 2% unchanged. About 25% is excreted in urine and 63% is excreted in feces. The elimination half-life of tiagabine is 4.5 to 9.0 hours. The half-life of tiagabine was found to be decreased by 50 to 65% to 3.8 to 4.9 hours (range 2–5 hours) in patients whose hepatic enzymes had been induced with other anticonvulsants including carbamazepine, phenytoin, primidone, and phenobarbital. In addition, the half-life of tiagabine is extended to 11.7 to 15.9 hours in hepatic dysfunction. These settings as such may require dose adjustment.

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.

What is cardarine also known as?

Cardarine is commonly known as GW501516 or GW-1516. These names refer to the same synthetic compound. It is not a brand-name approved medicine.

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