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Background And Regulatory Status — Questions and Answers

By Editorial Desk · published 2026-01-29 · last reviewed 2026-02-19 · Topic

The short version of PPAR delta fits in a sentence. The long version — which is the one that helps — is below.

Reviewed 2026-02-19. Anything still debated is marked as such rather than presented as settled.

Background and Regulatory Status

Sporting authorities added GW501516 to prohibited lists after it appeared in athlete samples and online markets. The World Anti-Doping Agency classifies it as a hormone and metabolic modulator, and its use can lead to an anti-doping rule violation. Some early laboratory work suggested effects on fatty acid oxidation and endurance-related metabolism in animals, but those findings do not establish safe or effective use in people. Reports of adverse events in humans are scarce and often anecdotal, which complicates risk assessment.

Legal status varies by country. In some places, cardarine is controlled under medicines or psychoactive substances laws; in others, it may be sold with minimal oversight as a research chemical. Customs agencies have intercepted shipments, and several national health agencies have issued warnings about products marketed for bodybuilding or performance enhancement. The lack of a standardized pharmaceutical supply means identity, purity, and contamination levels can differ widely between samples. These factors make cardarine a regulatory and public health concern rather than a conventional prescription drug.

Cardarine is a common name for GW501516, a synthetic compound first described in the 1990s as a selective agonist of the peroxisome proliferator-activated receptor delta. It was studied in preclinical models for metabolic and cardiovascular conditions, but it has not been approved as a medicine in the United States, Europe, or other major jurisdictions. Retail products labeled as cardarine are generally research chemicals or supplements, not pharmaceutical formulations. Because human safety and efficacy data remain limited, regulatory agencies treat it as an unapproved substance rather than a therapeutic product.

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.

Cardarine at a glance

PropertyValueNotes
IUPAC name{4-[({4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-5-yl}methyl)sulfanyl]phenoxy}acetic acidSystematic name for GW501516
CAS Registry Number317318-70-0Unique identifier for the parent compound
Molecular formulaC21H18F3NO3S2Includes carbon, hydrogen, fluorine, nitrogen, oxygen, and sulfur
Molecular weight453.5 g/molApproximate value for the neutral form
AppearanceWhite to off-white powderTypical description for purified laboratory material

Mechanism and Detection

GW501516 acts as a ligand for PPAR delta, a nuclear receptor that regulates transcription of genes involved in fatty acid oxidation and energy use. Activation of this receptor in skeletal muscle shifts metabolism toward fat burning in animal models. The compound does not burn fat directly; it changes gene expression over hours to days. Researchers study it to understand metabolic flexibility and exercise adaptation. Effects observed in rodents are not automatically expected in humans.

Preclinical research reported that GW501516 increased running endurance in mice and improved lipid profiles in some animal species. Early human trials explored effects on high-density lipoprotein cholesterol, triglycerides, and glucose handling, but the program was discontinued. Published human data are sparse and do not establish efficacy for any condition. Studies also examined PPAR delta in cancer biology, with conflicting findings across models. The relationship between receptor activation, tissue context, and disease risk remains an active area of investigation.

Anti-doping laboratories identify GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the usual matrix, and detection can occur after the parent compound has cleared from blood. The exact detection window depends on dose, formulation, individual metabolism, and assay sensitivity. Because the compound is prohibited at all times, athletes are subject to testing in and out of competition. Analytical methods continue to improve as new metabolites and designer analogs are characterized.

Related pages on this site

Cardarine as Investigational PPARδ Agonist

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.

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.

Background and Research Context

Cardarine is a common name for GW501516, a synthetic compound developed in the 1990s through research collaborations involving GlaxoSmithKline. It belongs to a class of molecules known as peroxisome proliferator-activated receptor delta agonists. Early studies explored its effects on lipid metabolism and energy expenditure in animal models. The compound was never approved as a human medicine, and clinical development was discontinued. In the years since, it has appeared in fitness and bodybuilding communities as a performance-enhancing substance. Regulatory agencies classify it as an unapproved drug.

PPARδ is a nuclear receptor that regulates gene expression related to fatty acid oxidation, glucose homeostasis, and mitochondrial function. GW501516 binds to this receptor with high affinity and activates downstream signaling in skeletal muscle and other tissues. Animal studies reported increased endurance and altered fuel preference, but human data remain limited and inconsistent. The precise relationship between receptor activation and observed physiological changes is still an area of active investigation. Researchers have also examined whether the compound affects inflammation or cell proliferation. No approved therapeutic indication exists for cardarine.

Notes from published material

=== Nervous system === Progesterone, like pregnenolone and dehydroepiandrosterone (DHEA), belongs to an important group of endogenous steroids called neurosteroids. The steroid can be metabolized within all parts of the central nervous system. Neurosteroids are neuromodulators and are neuroprotective, neurogenic, and regulate neurotransmission and myelination. The effects of progesterone as a neurosteroid are mediated predominantly through its interactions with non-nuclear PRs, namely the mPRs and PGRMC1, as well as certain other receptors, such as the σ1 and nACh receptors.

Concomitant use of nitric oxide donors, organic nitrites and nitrates, such as: nitroglycerin isosorbide mononitrate isosorbide dinitrate sodium nitroprusside alkyl nitrites (commonly known as "poppers") Concomitant use of soluble guanylyl cyclase stimulators, such as riociguat Known hypersensitivity to sildenafil Sildenafil should not be used if sexual activity is inadvisable due to underlying cardiovascular risk factors.

== Clinical trial == The National Institutes of Health announced on 27 February 2015 the commencement of a randomized controlled trial of ZMapp to be conducted in Liberia and the United States. From March 2015 through November 2015, 72 individuals infected with the Ebola virus were enrolled in the trial; investigators stopped enrolling new subjects in January 2016, having failed to reach its enrollment goal of 200 due to the waning of the Ebola outbreak. As a result, although a 40% lower risk of death was calculated for those who received ZMapp, the difference was not statistically significant and ultimately it could not be determined whether the use of ZMapp was superior to the optimized standard of care alone. However, ZMapp was found to be safe and well tolerated.

Sources: en.wikipedia.org

Background from the literature

To these words, La Feuille villageoise adds: "The example of honest, good farmers and landlords will suffice to familiarize the most stubborn day laborer with this new food; we could also use the ingenious means that were used in Ireland to accustom the least educated and least well-to-do portion of the people. In the schools, when a child had learned his lesson well, he was given a potato as a reward. When he had earned the prize for wisdom as well as for memory, he was given several; he ate them with delight; his classmates envied him, or feasted on the portion he was willing to give them. Sometimes he brought his apple home; the parents tasted it and found it good. Insensibly, the general repugnance of the people fell away, and it was not two generations before the potato became the favorite stew of the Irish."

Ketoacidosis is caused by the uncontrolled production of ketone bodies. Usually the production of ketones is carefully controlled by several hormones, most importantly insulin. If the mechanisms that control ketone production fail, ketone levels may become dramatically elevated and cause dangerous changes in physiology such as a metabolic acidosis.

Einstein's parent institution, Montefiore Health System, is a private non-profit healthcare system and one of the largest employers in New York. It comprises 15 member hospitals, including Montefiore Einstein Medical Center and Children's Hospital at Montefiore, and has the busiest emergency room in New York City and the ninth busiest in the United States. The system was founded in 1884 and is named for Moses Montefiore, a British financier and the Sheriff of London. Einstein first became affiliated with Montefiore in 1963, with Montefiore attending physicians serving as Einstein faculty. By 1969, financial troubles led Yeshiva University to contract its Jack D. Weiler Hospital to the Montefiore Medical Center. In 1980, the college's Department of Medicine merged with Montefiore. In the 2010s, Yeshiva University's mounting financial troubles—caused in part by Einstein's high operational costs and a $110 million loss to Bernie Madoff's Ponzi scheme in 2008—led the university to transfer ownership of the medical school to Montefiore in 2015. Although the deal's details were largely kept private, Einstein became a new entity with 51 percent ownership by Montefiore and 49 percent by Yeshiva. Montefiore assumed all operational and financial responsibilities. Yeshiva continued to grant Einstein's degrees until 2019, when the medical school achieved independent degree-granting authority. In 2021, Yeshiva and Montefiore launched a joint BA/BS-MD program for students entering Yeshiva.

Sources: en.wikipedia.org

Frequently asked questions

Is cardarine approved for human use?

No. Major drug regulators have not approved GW501516 for treating any medical condition. Products sold as cardarine are typically unapproved research chemicals or supplements, so their contents and safety are not assured.

Why is cardarine banned in sport?

It is prohibited by the World Anti-Doping Agency as a hormone and metabolic modulator. Athletes who test positive for GW501516 can face sanctions, including suspensions and loss of results.

What is the difference between cardarine and GW501516?

Cardarine is a common or trade-style name, while GW501516 is the research code for the same chemical entity. Some sources also use Endurobol or GSK-516. The names refer to the same compound, not distinct drugs.

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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