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Background And Research Context — Explained

By Editorial Desk · published 2026-04-22 · last reviewed 2026-05-23 · Data

PPARδ comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.

Last reviewed on 2026-05-23. Where a claim depends on a specific study, the study is described rather than over-claimed.

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.

In laboratory settings, cardarine is studied as a tool compound for probing PPARδ biology. Published experiments often use cell cultures, rodent models, or isolated tissues. Some investigations focus on metabolic effects, while others assess potential risks such as carcinogenicity observed in long-term animal studies. Because human trials are sparse, most knowledge comes from preclinical work and adverse event reports. Scientific literature frequently notes the gap between animal findings and human outcomes. The compound is not a dietary supplement and is not intended for human consumption.

Background and Regulatory History

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.

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.

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.

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.

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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.

Mechanism and Detection Methods

GW501516 acts as a selective agonist at PPARδ, a nuclear receptor that regulates transcription of genes involved in lipid handling and energy metabolism. Activation of PPARδ in preclinical models increases fatty acid oxidation, mitochondrial biogenesis, and exercise endurance in rodents. These effects have made the compound a subject of metabolic research and also a target for sport anti-doping rules. In humans, however, controlled studies are limited, and whether similar endurance or metabolic changes occur at tolerated exposures remains an open question. The receptor’s broad tissue distribution also means downstream effects may vary by organ and condition.

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.

Background from the literature

Murphree developing centrifuges, and Arthur Compton responsible for theoretical studies and design. On 23 April 1942, Met Lab scientists discussed seven possible ways to extract plutonium from irradiated uranium, and decided to pursue investigation of all seven. On 17 June, the first batch of uranium nitrate hexahydrate (UNH) was undergoing neutron bombardment in the Washington University in St. Louis cyclotron. On 27 July, the irradiated UNH was ready for Glenn T. Seaborg's team. On 20 August, using ultramicrochemistry techniques, they successfully extracted plutonium. In May 1942, Gertrude Scharff Goldhaber at Brookhaven National Laboratory reports for the first the emission of multiple neutrons during spontaneous fission of uranium. Her research was kept a secret. In April 1939, creating a chain reaction in natural uranium became the goal of Fermi and Szilard, as opposed to isotope separation. Their first efforts involved five hundred pounds of uranium oxide from the Eldorado Radium Corporation. Packed into fifty-two cans two inches in diameter and two feet long in a tank of manganese solution, they were able to confirm more neutrons were emitted than absorbed. However, the hydrogen within the water absorbed the slow neutrons necessary for fission. Carbon in the form of graphite, was then considered, because of its smaller capture cross section. In April 1940, Fermi was able to confirm carbon's potential for a slow-neutron chain reaction, after receiving National Carbon Company's graphite bricks at their Pupin Laboratories.

After Markov's death the wound on Kostov's back was examined and a ricin-laced pellet identical to the one used against Markov was removed. Several terrorist individuals and groups have experimented with ricin or planned to use it. There have been incidents of the poison being mailed to US politicians. For example, on 29 May 2013 two anonymous letters sent to New York City Mayor Michael Bloomberg contained traces of it. Another was sent to the offices of Mayors Against Illegal Guns in Washington, D.C. A letter containing ricin was also reported to have been sent to American President Barack Obama at the same time. Shannon Richardson, an actress, was later charged with the crime, and pleaded guilty that December; she was sentenced to 18 years in prison plus a restitution fine of US$367,000. On 2 October 2018, two letters suspected of containing ricin were sent to The Pentagon, one addressed to Secretary of Defense James Mattis, and the other to Chief of Naval Operations, Admiral John Richardson. A letter was received on 23 July 2019 at Pelican Bay State Prison in California which claimed to contain a suspicious substance. Authorities later confirmed it contained ricin; no detrimental exposures were identified. In 2020, some media in the Czech Republic reported, based on intelligence information, that a person carrying a Russian diplomatic passport and ricin had arrived in Prague with the intention of assassinating three politicians. Russian president Vladimir Putin denied the reports.

== Structure == Apart from their subcellular location and the abundance of acidic residues (Asp and Glu), these proteins do not share many structural similarities. Only one short region, located in the C-terminal section, is conserved in all these proteins. Chromogranins and secretogranins together share a C-terminal motif, whereas chromogranins A and B share a region of high similarity in their N-terminal section; this region includes two cysteine residues involved in a disulfide bond. There are considerable differences in the amino acid composition between different animals. Commercial assays for measuring human CGA can usually not be used for measuring CGA in samples from other species. Some specific parts of the molecule have a higher degree of amino acid homology and methods where the antibodies are directed against specific epitopes can be used to measure samples from different animals. Region-specific assays measuring defined parts of CGA, CGB and SG2 can be used for measurements in samples from cats and dogs.

Sources: en.wikipedia.org

Reference notes

Napoleon took the reserve of the Army of the North, and reunited his forces with those of Ney to pursue Wellington's army, after he ordered Marshal Grouchy to take the right wing of the Army of the North and stop the Prussians regrouping. In the first of a series of miscalculations, both Grouchy and Napoleon failed to realise that the Prussian forces were already reorganised and were assembling at the city of Wavre. The French army did nothing to stop a rather leisurely retreat that took place throughout the night and into the early morning by the Prussians. As the 4th, 1st, and 2nd Prussian Corps marched through the town towards Waterloo, the 3rd Prussian Corps took up blocking positions across the river, and although Grouchy engaged and defeated the Prussian rearguard under the command of Lt-Gen von Thielmann in the Battle of Wavre (18–19 June) it was 12 hours too late. In the end, 17,000 Prussians had kept 33,000 badly needed French reinforcements off the field. Napoleon delayed the start of fighting at the Battle of Waterloo on the morning of 18 June for several hours while he waited for the ground to dry after the previous night's rain. By late afternoon, the French army had not succeeded in driving Wellington's forces from the escarpment on which they stood. When the Prussians arrived and attacked the French right flank in ever-increasing numbers, Napoleon's strategy of keeping the coalition armies divided had failed and a combined coalition general advance drove his army from the field in confusion.

=== MeSH D12.644.276 – intercellular signaling peptides and proteins === MeSH D12.644.276.100 – angiogenic proteins MeSH D12.644.276.100.100 – angiopoietins MeSH D12.644.276.100.100.100 – angiopoietin-1 MeSH D12.644.276.100.100.200 – angiopoietin-2 MeSH D12.644.276.100.450 – angiostatic proteins MeSH D12.644.276.100.450.500 – angiostatins MeSH D12.644.276.100.450.750 – endostatins MeSH D12.644.276.100.800 – vascular endothelial growth factors MeSH D12.644.276.100.800.200 – vascular endothelial growth factor a MeSH D12.644.276.100.800.300 – vascular endothelial growth factor b MeSH D12.644.276.100.800.400 – vascular endothelial growth factor c MeSH D12.644.276.100.800.500 – vascular endothelial growth factor d MeSH D12.644.276.100.800.600 – vascular endothelial growth factor, endocrine-gland-derived MeSH D12.644.276.174 – cytokines MeSH D12.644.276.174.050 – autocrine motility factor MeSH D12.644.276.174.200 – chemokines MeSH D12.644.276.174.200.070 – beta-thromboglobulin MeSH D12.644.276.174.200.100 – chemokines, c MeSH D12.644.276.174.200.110 – chemokines, cc MeSH D12.644.276.174.200.120 – chemokines, cxc MeSH D12.644.276.174.200.130 – chemokines, cx3c MeSH D12.644.276.174.200.508 – interleukin-8 MeSH D12.644.276.174.200.600 – macrophage inflammatory proteins MeSH D12.644.276.174.200.600.500 – macrophage inflammatory protein-1 MeSH D12.644.276.174.200.610 – monocyte chemoattractant proteins MeSH D12.644.276.174.200.610.600 – monocyte chemoattractant protein-1 MeSH D12.644.276.174.200.700 – platelet factor 4 MeSH D12.644.276.174.200.750 – rantes MeSH D12.644.276.174.400 – growth substances MeSH D12.644.276.174.400.442 – hematopoietic cell growth factors MeSH D12.644.276.174.400.442.240 – colony-stimulating factors MeSH D12.644.276.174.400.442.240.075 – colony-stimulating factors, recombinant MeSH D12.644.276.174.400.442.240.075.350 – granulocyte colony stimulating factor, recombinant MeSH D12.644.276.174.400.442.240.075.350.275 – filgrastim MeSH D12.644.276.174.400.442.240.075.375 – granulocyte macrophage colony-stimulating factors, recombinant MeSH D12.644.276.174.400.442.240.150 – erythropoietin MeSH D12.644.276.174.400.442.240.150.250 – erythropoietin, recombinant MeSH D12.644.276.174.400.442.240.150.250.250 – epoetin alfa MeSH D12.644.276.174.400.442.240.350 – granulocyte colony-stimulating factor MeSH D12.644.276.174.400.442.240.350.375 – granulocyte colony stimulating factor, recombinant MeSH D12.644.276.174.400.442.240.350.375.275 – filgrastim MeSH D12.644.276.174.400.442.240.375 – granulocyte-macrophage colony-stimulating factor MeSH D12.644.276.174.400.442.240.375.275 – granulocyte macrophage colony-stimulating factors, recombinant MeSH D12.644.276.174.400.442.240.400 – interleukin-3 MeSH D12.644.276.174.400.442.240.500 – macrophage colony-stimulating factor MeSH D12.644.276.174.400.442.240.750 – thrombopoietin MeSH D12.644.276.174.400.442.800 – stem cell factor MeSH D12.644.276.174.400.505 – interleukins MeSH D12.644.276.174.400.505.501 – interleukin-1 MeSH D12.644.276.174.400.505.502 – interleukin-2 MeSH D12.644.276.174.400.505.503 – interleukin-3 MeSH D12.644.276.174.400.505.504 – interleukin-4 MeSH D12.644.276.174.400.505.505 – interleukin-5 MeSH D12.644.276.174.400.505.506 – interleukin-6 MeSH D12.644.276.174.400.505.507 – interleukin-7 MeSH D12.644.276.174.400.505.508 – interleukin-8 MeSH D12.644.276.174.400.505.509 – interleukin-9 MeSH D12.644.276.174.400.505.510 – interleukin-10 MeSH D12.644.276.174.400.505.511 – interleukin-11 MeSH D12.644.276.174.400.505.512 – interleukin-12 MeSH D12.644.276.174.400.505.513 – interleukin-13 MeSH D12.644.276.174.400.505.514 – interleukin-14 MeSH D12.644.276.174.400.505.515 – interleukin-15 MeSH D12.644.276.174.400.505.516 – interleukin-16 MeSH D12.644.276.174.400.505.517 – interleukin-17 MeSH D12.644.276.174.400.505.518 – interleukin-18 MeSH D12.644.276.174.400.800 – transforming growth factor beta MeSH D12.644.276.174.420 – hepatocyte growth factor MeSH D12.644.276.174.440 – interferons MeSH D12.644.276.174.440.890 – interferon type i MeSH D12.644.276.174.440.890.125 – interferon type i, recombinant MeSH D12.644.276.174.440.890.125.100 – interferon alfa-2a MeSH D12.644.276.174.440.890.125.150 – interferon alfa-2b MeSH D12.644.276.174.440.890.125.200 – interferon alfa-2c MeSH D12.644.276.174.440.890.250 – interferon-alpha MeSH D12.644.276.174.440.890.250.100 – interferon alfa-2a MeSH D12.644.276.174.440.890.250.150 – interferon alfa-2b MeSH D12.644.276.174.440.890.250.200 – interferon alfa-2c MeSH D12.644.276.174.440.890.275 – interferon-beta MeSH D12.644.276.174.440.893 – interferon type ii MeSH D12.644.276.174.440.893.510 – interferon-gamma, recombinant MeSH D12.644.276.174.480 – lymphokines MeSH D12.644.276.174.480.350 – interferon type ii MeSH D12.644.276.174.480.372 – interleukin-2 MeSH D12.644.276.174.480.428 – leukocyte migration-inhibitory factors MeSH D12.644.276.174.480.438 – lymphotoxin MeSH D12.644.276.174.480.615 – macrophage-activating factors MeSH D12.644.276.174.480.615.350 – interferon type ii MeSH D12.644.276.174.480.625 – macrophage migration-inhibitory factors MeSH D12.644.276.174.480.640 – neuroleukin MeSH D12.644.276.174.480.700 – suppressor factors, immunologic MeSH D12.644.276.174.480.750 – transfer factor MeSH D12.644.276.174.500 – monokines MeSH D12.644.276.174.500.400 – interleukin-1 MeSH D12.644.276.174.500.800 – tumor necrosis factor-alpha MeSH D12.644.276.174.750 – tumor necrosis factors MeSH D12.644.276.174.750.500 – lymphotoxin MeSH D12.644.276.174.750.750 – tumor necrosis factor-alpha MeSH D12.644.276.211 – endothelial growth factors MeSH D12.644.276.249 – endothelins MeSH D12.644.276.249.225 – endothelin-1 MeSH D12.644.276.249.235 – endothelin-2 MeSH D12.644.276.249.245 – endothelin-3 MeSH D12.644.276.500 – ephrins MeSH D12.644.276.500.100 – ephrin-A1 MeSH D12.644.276.500.200 – ephrin-A2 MeSH D12.644.276.500.300 – ephrin-A3 MeSH D12.644.276.500.400 – ephrin-A4 MeSH D12.644.276.500.500 – ephrin-A5 MeSH D12.644.276.500.600 – ephrin-b1 MeSH D12.644.276.500.700 – ephrin-b2 MeSH D12.644.276.500.800 – ephrin-b3 MeSH D12.644.276.625 – epidermal growth factor MeSH D12.644.276.750 – fibroblast growth factors MeSH D12.644.276.750.110 – fibroblast growth factor 1 MeSH D12.644.276.750.120 – fibroblast growth factor 2 MeSH D12.644.276.750.130 – fibroblast growth factor 3 MeSH D12.644.276.750.140 – fibroblast growth factor 4 MeSH D12.644.276.750.150 – fibroblast growth factor 5 MeSH D12.644.276.750.160 – fibroblast growth factor 6 MeSH D12.644.276.750.170 – fibroblast growth factor 7 MeSH D12.644.276.750.180 – fibroblast growth factor 8 MeSH D12.644.276.750.190 – fibroblast growth factor 9 MeSH D12.644.276.750.200 – fibroblast growth factor 10 MeSH D12.644.276.812 – i-kappa b kinase MeSH D12.644.276.875 – kinins MeSH D12.644.276.875.169 – bradykinin MeSH D12.644.276.875.169.400 – kallidin MeSH D12.644.276.875.654 – kininogens MeSH D12.644.276.875.654.350 – kininogen, high-molecular-weight MeSH D12.644.276.875.654.400 – kininogen, low-molecular-weight MeSH D12.644.276.875.900 – tachykinins MeSH D12.644.276.875.900.354 – eledoisin MeSH D12.644.276.875.900.475 – kassinin MeSH D12.644.276.875.900.500 – neurokinin a MeSH D12.644.276.875.900.550 – neurokinin b MeSH D12.644.276.875.900.800 – physalaemin MeSH D12.644.276.875.900.866 – substance p MeSH D12.644.276.937 – neuregulins MeSH D12.644.276.937.750 – neuregulin-1 MeSH D12.644.276.952 – parathyroid hormone-related protein MeSH D12.644.276.968 – platelet-derived growth factor MeSH D12.644.276.968.650 – proto-oncogene proteins c-sis MeSH D12.644.276.976 – somatomedins MeSH D12.644.276.976.400 – insulin-like growth factor i MeSH D12.644.276.976.420 – insulin-like growth factor ii MeSH D12.644.276.984 – transforming growth factors MeSH D12.644.276.984.700 – transforming growth factor alpha MeSH D12.644.276.984.720 – transforming growth factor beta MeSH D12.644.276.992 – tumor necrosis factors MeSH D12.644.276.992.500 – lymphotoxin MeSH D12.644.276.992.750 – tumor necrosis factor-alpha MeSH D12.644.276.996 – wnt proteins MeSH D12.644.276.996.500 – wnt1 protein MeSH D12.644.276.996.750 – wnt2 protein

Drug Information Association (DIA) EVENT: DIA/FDA Orphan Drug Designation Workshop November 2010 Archived 2010-10-28 at the Wayback Machine European Commission - The Orphan drugs strategy List of European Orphan Drugs USA Food and Drug Administration: The Orphan Drug Act (as amended) US FDA List of Orphan Designations and Approvals

Sources: en.wikipedia.org

Notes from published material

Lexanopadol (INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name), also known by its developmental code name GRT-6006, is an opioid receptor modulator which was under development for the treatment of pain. It is taken orally. The drug acts as a dual agonist of the μ-opioid receptor and nociceptin receptor. It is thought that the combination of these activities may confer enhanced analgesic efficacy. Lexanopadol was under development by Grünenthal. It reached phase 1 or 2 clinical trials prior to the discontinuation of its development, with no further development reported by 2016. The drug was a follow-on compound to cebranopadol (GRT-6005).

Obesity is a risk factor for certain conditions, including diabetes, cancer, cardiovascular disease, high blood pressure, and non-alcoholic fatty liver disease. Reduction of obesity lowers those risks. A 1 kilogram (2.2 lb) loss of body weight has been associated with an approximate 1 millimetre of mercury (0.13 kPa) drop in blood pressure. Intentional weight loss is associated with cognitive performance improvements in overweight and obese individuals.

Mercury is commonly used in small scale gold mining. To do this, large amounts of mercury are usually mixed with gold-containing materials to create a gold-mercury alloy called amalgam. To separate the gold, the amalgam is heated in a furnace causing the mercury to vaporize. During this process, miners are directly exposed to mercury vapors, and surrounding communities may be indirectly exposed through contaminated air, water, and soil. Continuous high levels of mercury vapor inhalation can cause a variety of health effects. Inhalation may result in tremors, mood swings, muscle weakness, memory loss, or headaches. Prolonged exposure can lead to kidney damage, respiratory failure, and even death. Ingestion of mercury through contaminated water, food, or soil pose great risk to pregnant women and their developing fetuses. When born, this can impair the infants' cognitive functions, memory, language development, and fine motor skills. Despite its widespread use across countries, mercury exposure in artisanal small-scale gold mining is preventable. Mercury-free techniques like direct smelting result in gold recovery without the need of mercury resulting in the elimination of mercury. In this method, borax is used to decrease the viscosity and melting temperature of non-gold minerals so they can be easily separated from the gold. This not only results in improved worker and community health but also lower in cost and eco-friendly.

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 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.

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