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Background And Research Context — Complete Guide

By Editorial Desk · published 2026-04-18 · last reviewed 2026-05-20 · Data

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

Reviewed 2026-05-20. Anything still debated is marked as such rather than presented as settled.

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.

Regulatory Status and Detection Context

Cardarine is not approved for human therapeutic use in any major jurisdiction. It appears on the World Anti-Doping Agency Prohibited List as a PPARδ agonist within the hormone and metabolic modulators category. Sports organizations test for it because it has been detected in athlete samples and seized products. Regulatory actions against marketed research chemical versions have occurred in several countries, though enforcement varies. Availability through unregulated channels complicates oversight.

Analytical laboratories typically identify cardarine and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is a common matrix in anti-doping testing, while blood and tissue may be used in research settings. Detection windows depend on the assay, the sample matrix, and the compound's metabolism. Because cardarine is extensively metabolized, laboratories often target specific metabolites to improve sensitivity and confirmation. Reference standards are required for reliable quantification. Method validation includes checks for selectivity, linearity, and carryover.

A persistent misconception is that cardarine is a fat-burning drug or a safe alternative to anabolic steroids. No approved therapeutic product exists, and human safety data are limited. The tumor findings in rodents remain a central concern in scientific reviews. Products sold online may contain inaccurate labels, impurities, or different compounds entirely, which complicates any assessment of effects. Independent testing of such products has reported frequent mislabeling. For these reasons, discussions in the literature emphasize risks and unknowns rather than benefits.

Cardarine at a glance

PropertyValueNotes
CAS Registry Number317318-70-0Unique identifier for the compound.
Chemical classPPARδ agonistSynthetic ligand for peroxisome proliferator-activated receptor delta.
AppearanceWhite to off-white solidTypical form of research-grade material.
SolubilitySoluble in DMSO and ethanolPoorly soluble in water.
Typical storage-20°CRecommended for long-term storage of stock solutions.

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.

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Mechanism and Research Context

GW501516 acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in transcription of genes related to lipid handling and energy use. Activation of PPARδ can shift skeletal muscle toward greater fatty acid oxidation in animal models, which is one reason it drew interest for metabolic disease and exercise research. The exact downstream effects depend on tissue, species, dose, and duration. Human data are sparse, so many proposed benefits remain hypotheses rather than established clinical outcomes.

Laboratory studies have examined GW501516 in cell cultures and rodents for conditions such as dyslipidemia, insulin resistance, and obesity. Some trials in humans were initiated, but development was discontinued after preclinical findings raised concerns about cancer in certain models. Those findings do not prove that the compound causes cancer in people, but they contributed to regulatory caution. Later reviews often describe the evidence as preliminary and insufficient for assessing long-term safety.

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 Regulatory Status

Cardarine is a common name for GW501516, an investigational compound developed in the 1990s for metabolic conditions. It acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in lipid and energy metabolism. The compound is frequently mislabeled as a selective androgen receptor modulator, or SARM, but its molecular target is different. GW501516 reached early clinical testing before development was discontinued. It has no approved therapeutic use in any country. The name cardarine is not a formal international nonproprietary name.

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.

Supporting material

Urine replacement, which involves replacing dirty urine with clean urine from someone who is not taking banned substances. Urine replacement can be done by catheterization or with a prosthetic penis such as The Original Whizzinator. Diuretics, used to cleanse the system before having to provide a sample (which have also been placed in lists of banned substances themselves to circumvent this practice). Blood transfusions, which increase the blood's oxygen carrying capacity, in turn increasing endurance without the presence of drugs that could trigger a positive test result. To avoid being tested during training periods, athletes can make themselves unavailable. To mitigate this, athletes have to report their location at any time. If intended doping tests could not be done because the athlete could not be found, three times during a year, it's considered a doping violation, same as refusing a test. There is a website and a phone app, called ADAMS, in which athletes are expected to report their location.

== Amino acid propensities == The original Chou–Fasman parameters found some strong tendencies among individual amino acids to prefer one type of secondary structure over others. Alanine, glutamate, leucine, and methionine were identified as helix formers, while proline and glycine, due to the unique conformational properties of their peptide bonds, commonly end a helix. The original Chou–Fasman parameters were derived from a very small and non-representative sample of protein structures due to the small number of such structures that were known at the time of their original work. These original parameters have since been shown to be unreliable and have been updated from a current dataset, along with modifications to the initial algorithm. The Chou–Fasman method takes into account only the probability that each individual amino acid will appear in a helix, strand, or turn. Unlike the more complex GOR method, it does not reflect the conditional probabilities of an amino acid to form a particular secondary structure given that its neighbors already possess that structure. This lack of cooperativity increases its computational efficiency but decreases its accuracy, since the propensities of individual amino acids are often not strong enough to render a definitive prediction.

In April 1976, he called upon his supporters in universities to establish "revolutionary student councils" and drive out "reactionary elements". During that year, anti-Gaddafist student demonstrations broke out at the universities of Tripoli and Benghazi, resulting in clashes with both Gaddafist students and police. The RCC responded with mass arrests and introduced compulsory national service for young people. In January 1977, two dissenting students and a number of army officers were publicly hanged; Amnesty International condemned it as the first time in Gaddafist Libya that dissenters had been executed for purely political crimes. Dissent also arose from conservative clerics and the Muslim Brotherhood, who accused Gaddafi of moving towards Marxism and criticized his abolition of private property as being against the Islamic sunnah; these forces were then persecuted as anti-revolutionary, while all privately owned Islamic colleges and universities were shut down.

Sources: en.wikipedia.org

Notes from published material

== Mechanism of action == Malacidins appear to take on their active conformation after they bind to calcium; the calcium-bound molecule then appears to bind to lipid II, a bacterial cell wall precursor molecule, leading to destruction of the cell wall and death of the bacteria. Therefore, they would be a new member of the class of calcium-dependent antibiotics. The discovery of malacidins supported the view that the calcium-dependent antibiotics are a larger class than previously thought.

In this way protein dynamics can induce a conformational change in the structure of the protein via long-range allostery with other hydrophobic and hydrophilic residues in the protein. One such example of the regulatory role that phosphorylation plays is the p53 tumor suppressor protein. The p53 protein is heavily regulated and contains more than 18 different phosphorylation sites. Activation of p53 can lead to cell cycle arrest, which can be reversed under some circumstances, or apoptotic cell death. This activity occurs only in situations wherein the cell is damaged or physiology is disturbed in normal healthy individuals. Upon the deactivating signal, the protein becomes dephosphorylated again and stops working. This is the mechanism in many forms of signal transduction, for example the way in which incoming light is processed in the light-sensitive cells of the retina. Regulatory roles of phosphorylation include:

=== Fixed election dates === Ford's government announced a proposal on October 27, 2025, to eliminate fixed election dates as part of a series of changes to provincial election law in order to "return Ontario to an electoral process that served our province well... prior to the imposition of American-style fixed election dates." The bill removing fixed election dates received royal assent and went into effect on November 27.

Sources: en.wikipedia.org

Further detail

=== January === 1 January – A visit by Thor the Walrus to Scarborough harbour, North Yorkshire overnight on New Year's Eve results in the town's New Year fireworks celebrations being cancelled to let the walrus rest for his journey to the Arctic. He was previously spotted at Pagham Harbour, Calshot, Hampshire in December 2022. 2 January Three people are killed by a fire at the New County Hotel in Perth, Scotland. Thor the Walrus makes an appearance in Blyth, Northumberland. 3 January – 40,000 railway workers who are members of the RMT union hold the first of two 48-hour strikes this week, severely disrupting train services in England, Scotland, and Wales. 5 January The government confirms it will not go ahead with a plan to privatise Channel 4. The Met Office confirms that 2022 was the UK's warmest year since records began in 1884, with an average annual temperature above 10 °C (50 °F) for the first time. BioNTech announces a strategic partnership with the UK government to provide up to 10,000 patients with personalised mRNA cancer immunotherapies by 2030. 6 January – COVID-19 in the UK: Almost three million people were infected with COVID-19 over the Christmas period (the highest since July 2022), the latest Office for National Statistics data suggests, with one in 20 having the virus in England, one in 18 in Wales, one in 25 in Scotland and one in 16 in Northern Ireland. XBB.1.5, the new Omicron variant of the virus, is believed to be responsible for one in 200 infections in the UK.

=== De novo sequencing === The pattern of fragmentation of a peptide allows for direct determination of its sequence by de novo sequencing. This sequence may be used to match databases of protein sequences or to investigate post-translational or chemical modifications. It may provide additional evidence for protein identifications performed as above.

"there are still uncertainties in the risk assessment that could not be completely eliminated by the German Mobile Telecommunication Research Program, in particular possible health risks of long-term exposure to high-frequency electromagnetic fields from cell phone calls in adults (intensive cell phone use over more than 10 years) and the question of whether the use of cell phones by children could have an effect on health. For these reasons, the Federal Office for Radiation Protection still considers preventive health protection (precaution) to be necessary: exposure to electromagnetic fields should be kept as low as possible."

Sources: en.wikipedia.org

Frequently asked questions

What is cardarine?

Cardarine is a common name for GW501516, a synthetic PPARδ agonist developed for research. It has not been approved as a medication in any country. It is classified as an unapproved drug and a prohibited substance in sport.

Is cardarine a steroid?

No. Cardarine is not an anabolic steroid; it belongs to a different chemical class that targets PPARδ. Steroids act primarily through androgen receptors, while cardarine acts through a nuclear receptor involved in metabolism.

What did animal studies find?

Some rodent studies reported increased endurance and changes in fat metabolism after cardarine exposure. Long-term studies in animals also raised concerns about cancer in certain tissues. Human trial data are limited, so these findings cannot be directly translated to people.

Is cardarine approved for any medical use?

No. Cardarine has not received approval for human therapeutic use in major jurisdictions. It remains an investigational compound.

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