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Background And Regulatory History — Questions and Answers

By Editorial Desk · published 2026-06-15 · last reviewed 2026-06-29 · News

Everything below concerns GW501516. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.

Updated 2026-06-29. 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.

Regulation and Detection

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.

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

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.

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.

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Cardarine as Investigational PPARδ Agonist

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.

Identity and Pharmacological Classification

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.

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.

Notes from published material

== Cell imaging == Chemical tags have been tailored for imaging technologies more so than fluorescent proteins because chemical tags can localize photosensitizers closer to the target proteins. Proteins can then be labeled and detected with imaging such as super-resolution microscopy, Ca2+-imaging, pH sensing, hydrogen peroxide detection, chromophore assisted light inactivation, and multi-photon light microscopy. In vivo imaging studies in live animals have been performed for the first time with the use of a monomeric protein derived from the bacterial haloalkane dehalogenase known as the Halo-tag. The Halo-tag covalently links to its ligand and allows for better expression of soluble proteins.

A phosphorimidazolide is a chemical compound in which a phosphoryl mono-ester is covalently bound to a nitrogen atom in an imidazole ring. They are a type of phosphoramidate. These phosphorus (V) compounds are encountered as reagents used for making new phosphoanhydride bonds with phosphate mono-esters, and as reactive intermediates in phosphoryl transfer reactions in some enzyme-catalyzed transformations. They are also being studied as critical chemical intermediates for the polymerization of nucleotides in pre-biotic settings. They are sometimes referred to as phosphorimidazolidates, imidazole-activated phosphoryl groups, and P-imidazolides.

The outermost layer of the gastrointestinal wall consists of several layers of connective tissue and is either of serosa (below the diaphragm) or adventitia above the diaphragm. Regions of the gastrointestinal tract within the peritoneum (called Intraperitoneal) are covered with serosa. This structure consists of connective tissue covered by a simple squamous epithelium, called the mesothelium, which reduces frictional forces during digestive movements. The intraperitoneal regions include most of the stomach, first part of the duodenum, all of the small intestine, caecum and appendix, transverse colon, sigmoid colon and rectum. In these sections of the gut there is clear boundary between the gut and the surrounding tissue. These parts of the tract have a mesentery. Regions of the gastrointestinal tract behind the peritoneum (called retroperitoneal) are covered with adventitia. They blend into the surrounding tissue and are fixed in position (for example, the retroperitoneal section of the duodenum usually passes through the transpyloric plane). The retroperitoneal regions include the oral cavity, esophagus, pylorus of the stomach, distal duodenum, ascending colon, descending colon and anal canal.

==== Danger of misidentification ==== One danger of attempting to consume hallucinogenic or other wild mushrooms, especially for novice mushroom hunters, is the possibility of misidentification with toxic species. In one noted case, an otherwise healthy young Austrian man mistook the poisonous Cortinarius rubellus for P. semilanceata. As a result, he suffered end-stage kidney failure, and required a kidney transplant. In another instance, a young man developed cardiac abnormalities similar to those seen in Takotsubo cardiomyopathy, characterized by a sudden temporary weakening of the myocardium. A polymerase chain reaction-based test to specifically identify P. semilanceata was reported by Polish scientists in 2007.

Sources: en.wikipedia.org

Further detail

The US Department of Defense reports that US forces suffered 148 battle-related deaths, 35 to friendly fire. One pilot was listed as MIA. His remains were found and identified in August 2009. A further 145 Americans died in non-combat accidents. The UK suffered 47 deaths (nine to friendly fire, all by US forces), France nine. The other coalition countries, not including Kuwait, suffered 37 deaths (18 Saudis, one Egyptian, six UAE and three Qataris). At least 605 Kuwaiti soldiers were still missing 10 years after their capture. The largest single loss of life among coalition forces happened on 25 February 1991, when an Iraqi Al Hussein missile hit a US military barrack in Dhahran, Saudi Arabia, killing 28 US Army Reservists from Pennsylvania. In all, 190 coalition troops were killed by Iraqi fire during the war, 113 of whom were American, out of 358 coalition deaths. Another 44 soldiers were killed and 57 wounded by friendly fire. 145 soldiers died of exploding munitions or non-combat accidents. The largest accident among coalition forces happened on 21 March 1991, when a Royal Saudi Air Force C-130H crashed in heavy smoke on approach to Ras Al-Mishab Airport, Saudi Arabia. 92 Senegalese soldiers and six Saudi crew members were killed. The number of coalition wounded in combat was 776, including 458 Americans. 190 coalition troops were killed by Iraqi combatants, the rest of the 379 coalition deaths were from friendly fire or accidents. This number was much lower than expected. Among the American combat dead were four female soldiers.

==== Detection ==== Cabbage loopers possess olfactory receptor neurons on their antennae for detecting pheromones. The neurons are specifically located on two sensory structures called sensilla that differ in length and pore density. Male loopers have two types of neurons, and depending on which sensilla that are present, the neurons will detect female pheromones at varying sensitivities to each of the six pheromones. The neurons are most sensitive to the main component of the female pheromone blend, cis-7-dodecenyl acetate, and the male inhibitory signal, cis-7-dodecenol. The presence of cis-7-dodecenyl acetate is crucial for male response to female pheromones, as it is 80% of the entire blend. The base region of the antennae, where receptor neurons for this pheromone are located, has more sensory structures than the ends. The base region is also less likely to experience damage, showing the importance of detecting the pheromone. It is not clear why male neurons detect the inhibitory compound, as there is no evidence showing that females produce this compound. One possibility is that its presence in the female pheromone blend may be too small to be detected by scientific equipment. The inhibitory signal only elicits a response when delivered alongside female pheromones to avoid mixing signals from other species, suggesting that while it cannot be detected in the female pheromone blend, it has an important role in female detection. These neurons are also capable of recognizing and responding to cis-7-tetradecenyl acetate and cis-9-tetradecenyl acetate.

Routine toxicology studies have provided no evidence that moxonidine has any teratogenic, mutagenic or carcinogenic potential. No evidence has been found of serious adverse effects on organs or organ systems, and the drug has not been shown to have deleterious effects on perinatal or postnatal growth and development.

In Japan, public universities are run by local governments, either prefectural or municipal. According to the Ministry of Education, public universities have "provided an opportunity for higher education in a region and served the central role of intellectual and cultural base for the local community in the region" and are "expected to contribute to social, economical and cultural development in the region". This contrasts with the research-oriented aspects of national universities. In 2010, 127,872 students were attending 95 public universities, compared to 86 national universities and 597 private universities in Japan. Many public universities are relatively new; in 1980, there were only 34 public universities in Japan. Since July 2003, public universities may incorporate under the Local Independent Administrative Institutions Law.

== Epidemiology == Biliary atresia seems to affect females slightly more often than males, and Asians and African Americans more often than Caucasians. It is common for only one child in a pair of twins or within the same family to have the condition. There seems to be no link to medications or immunizations given immediately before or during pregnancy. Diabetes during pregnancy particularly during the first trimester seems to predispose to a number of distinct congenital abnormalities in the infant such as sacral agenesis, transposition of the great vessels and the syndromic form of biliary atresia.

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.

Is cardarine legal?

Legal status varies by country. It is not approved as a medicine, and it is prohibited in sport. Some jurisdictions restrict import, sale, or possession.

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