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Background And Regulatory History — Background and Details

By Editorial Desk · published 2025-12-26 · last reviewed 2026-01-14 · Info

Anti-doping raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.

This page was last updated on 2026-01-14 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.

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.

Mechanism and Safety Research

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.

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.

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.

Laboratory handling focuses on identity, purity, and stability. Reference standards are typically stored cold and dry, protected from light, because solutions can degrade over time. Analytical checks may use high-performance liquid chromatography with ultraviolet detection or mass spectrometry. Impurities and related substances can be separated chromatographically and compared with a known standard. Because cardarine is not an approved drug, compendial monographs are absent, and laboratories often rely on in-house methods. Reported purity varies among unregulated products and should not be assumed from a label.

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Identity and Regulatory Status

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.

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.

Identity and Pharmacological Mechanism

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.

The compound is typically described as a laboratory compound rather than a therapeutic product. Published reports have explored its role in lipid disorders, insulin sensitivity, and exercise metabolism, yet no major drug regulator has approved it for medical use. Commercial samples sold under the cardarine name may vary in purity and identity. Analytical confirmation is therefore necessary when the material is discussed in scientific or regulatory contexts. Its classification as a prohibited substance in sport further shapes how it is studied and reported.

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.

Further detail

American hot dog variations often have misleading names; they are commonly named for the geographical regions that allegedly inspired them instead of the regions in which they are most popular. For example, Michigan hot dogs and white hots are popular in upstate New York, whereas Coney Island hot dogs are popular in Michigan. Sauteed bell peppers, onions, and potatoes find their way into New Jersey's deep-fried Italian hot dog. Hot wieners, or weenies, are a staple in Rhode Island where they are sold at restaurants under the misleading name "New York System." Texas hot dogs are spicy variants found in upstate New York and Pennsylvania (and as "all the way dogs" in New Jersey), but not Texas. In the Philadelphia metro area, Texas Tommy refers to a hot dog variant in which the frank is topped with melted cheese (often cheddar) and wrapped in bacon. In the Midwest, the Chicago-style hot dog is served on a poppy seed bun and topped with mustard, fresh tomatoes, onions, "sport peppers", bright green relish, dill pickles, and celery salt. The "New York dog" or "New York style" hot dog is a natural-casing all-beef frank topped with sauerkraut and spicy brown mustard, onions optional, invented and popularized in New York City. Some baseball parks have signature hot dogs, such as Dodger Dogs at Dodger Stadium in Los Angeles, and Fenway Franks at Fenway Park in Boston.

== Further reading == Brown, Brandon P (2011). "Acupuncture." Magill's Medical Guide, 6th ed., vol. 1. Salem Press. ISBN 978-1-63700-107-3. Ulett GA (2002). "Acupuncture". In Shermer M (ed.). The Skeptic Encyclopedia of Pseudoscience. ABC-CLIO. pp. 283 ff. ISBN 978-1-57607-653-8. William FW, ed. (2013). "Acupuncture". Encyclopedia of Pseudoscience: From Alien Abductions to Zone Therapy. Routledge. pp. 3–4. ISBN 978-1-135-95522-9. Bivins, Roberta E. (2000). Acupuncture, Expertise, and Cross-Cultural Medicine. New York: Palgrave. ISBN 0-333-91893-2. FRONTLINE: The Alternative Fix - "What is acupuncture?" (4 November 2003). PBS Video.

=== From primary cancer to the meninges === NM is a secondary cancer meaning that it is the result of neoplastic cells that have metastasized from a primary cancer site. These cancers develop an enzyme that is able to break down blood vessels at a microscopic level. These cells enter the blood vessels and travel across the body. Once the brain is reached, they break down the blood–brain barrier to enter the Cerebrospinal Fluid (CSF). There the cancerous cells seed and disseminate into the leptomeninges which are composed of the arachnoid and the pia. The CSF continues to carry neoplastic cells through the brain tracts and spreads the cancerous cells. Lung cancer, breast cancer, and melanoma comprise the majority of solid tumors spreading to the leptomeninges. Although rare, meningeal carcinomatosis can arise from cervical cancer. Only eight cases of MC arising from squamous cell carcinoma of the uterine cervix are previously reported in the literature. Since NM is a result of primary cancer metastasis and can develop from primary brain tumors or parenchymal metastasis when tumor cells are lodged in small central nervous system (CNS) vasculature, causing local ischemia and vessel damage which result in tumor spillage into the Virchow-Robin spaces and providing access to the subarachnoid space.

Sources: en.wikipedia.org

Background from the literature

As of January 2026, there were 575 federally recognized tribes. There are approximately 326 Indian reservations. The tribes hold a government-to-government relationship with the U.S. federal government in Washington and are legally defined as domestic dependent nations with inherent tribal sovereignty rights. In addition to the five major territories, the U.S. also asserts sovereignty over the United States Minor Outlying Islands in the Pacific Ocean and the Caribbean. The seven undisputed islands without permanent populations are Baker Island, Howland Island, Jarvis Island, Johnston Atoll, Kingman Reef, Midway Atoll, and Palmyra Atoll. U.S. sovereignty over the unpopulated Bajo Nuevo Bank, Navassa Island, Serranilla Bank, and Wake Island is disputed.

== Method == Electron probe microanalysis (EMPA), Synchrotron micro-XRF (SR-M-XRF), Time-of-flight secondary ion mass spectrometry (TOF-SIMS), Laser induced breakdown spectroscopy (LIBS), Atomic emission spectrometry, x-ray fluorescence spectrometry with higher energy synchrotron radiation (SR-XFS) and Laser ablation-Inductively coupled plasma mass spectrometry (LA-ICP-MS) are all methods of gold fingerprinting. The most common method is LA-ICP-MS primarily because it is quasi-nondestructive, allowing for the preservation of the samples and convenient as samples require little to no preparation. Laser ablation allows for high spatial resolution sampling while the inductively coupled plasma mass spectrometry provides high sensitivity to identify extremely small amounts of trace elements within the gold. This method can also be conducted outside of a lab with the assistance of a portable device that uses a diode pumped solid state laser and fiber-optics, making fingerprinting more convenient as it eliminates the need for transfer of gold to a specific lab. Advantages of LA-ICP-MS include reduced sample preparation, no sample size requirements, reduced spectral interference and increased sample throughput. Over the past 32 years, LA-ICP-MS has been used for archaeological, biological and forensic purposes. For example a group of gold foil fragments dating back to the 5th Century B.C.E. were analysized by LA-ICP-MS uncovering information on their manufacturing process, function and relationship to one another.

This was also the belief of geologist Palmer, who convinced Steven Jones that the helium-3 occurring naturally in Earth perhaps came from fusion involving hydrogen isotopes inside catalysts like nickel and palladium. This led their team in 1986 to independently make the same experimental setup as Fleischmann and Pons (a palladium cathode submerged in heavy water, absorbing deuterium via electrolysis). Fleischmann and Pons had much the same belief, but they calculated the pressure to be of 1027 atmospheres, when cold fusion experiments achieve a loading ratio of only one to one, which has only between 10,000 and 20,000 atmospheres. John R. Huizenga says they had misinterpreted the Nernst equation, leading them to believe that there was enough pressure to bring deuterons so close to each other that there would be spontaneous fusions.

Sources: en.wikipedia.org

Further detail

Niacin as a chemical compound was first described by chemist Hugo Weidel in 1873 in his studies of nicotine, but that predated by many years the concept of food components other than protein, fat and carbohydrates that were essential for life. Vitamin nomenclature was initially alphabetical, with Elmer McCollum calling these fat-soluble A and water-soluble B. Over time, eight chemically distinct, water-soluble B vitamins were isolated and numbered, with niacin as vitamin B3.

=== Turnover === Research suggests that, at least in the United States, vegetarianism has a high turnover rate, with less than 20% of adopters persisting for more than a year. Research shows that lacking social support contributes to lapses. A 2019 analysis found that adhering to any kind of restricted diet (gluten-free, vegetarian, kosher, teetotal) was associated with feelings of loneliness and increased social isolation. Vegetarians or vegans who adopted their diet abruptly might be more likely to eventually abandon it when compared to individuals adopting their diet gradually with incremental changes.

=== 2026 Data breach and class action === On January 28, 2026, Panera Bread was hit by a cyber attack, along with other companies including Bumble and Match. The company revealed that contact information was the data involved. Later reporting noted that the aggressor was ShinyHunters, that they stole information on around 5 million people (14 million records), and subsequently leaked this information to the dark web. Two class action lawsuits were filed against the company shortly after, citing Panera Bread's failure to properly secure the personal information that was stolen.

== History == Cell display systems were first used in 1985, when peptides were genetically fused with proteins displayed on the M13 bacteriophage. Bacteriophage display is a commonly used cell display system, although it carries limitations in the size of proteins that can be displayed. Bacterial display was then introduced in 1986, allowing the surface display of larger proteins. Bacterial display systems were first introduced by Freudl et al. and Charbit et al. in 1986, when they used bacterial surface proteins OmpA and LamB to display peptides. Freudl et al. fused peptides with linkers with the ompA gene, causing the peptides to be expressed in the OmpA proteins. They showed that the proteins were now subject to cleavage by proteinase K. The non-OmpA peptides inserted were therefore a target of proteinase K. Insertion of the foreign peptides did not affect bacterial cell growth. Charbit et al. firstly defined the areas of the LamB protein that were "permissive" for foreign petide insertion (ie that did not lead to a complete loss of functionality of the protein). Then, they explored the versatility of the permissive sites (size limit, nature of the epitope,...) that were all located in surface-exposed loops of the trimeric outer membrane porin, aiming at developing multivalent live bacterial vaccines. This was the first evidence of using bacterial surface display techniques to express proteins on the surface of cells, without altering the function of the cell.

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 the main molecular target of cardarine?

It targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not act primarily on androgen receptors. This distinction separates it from SARMs.

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