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Background And Research Context — 2026 Update

By Editorial Desk · published 2026-01-27 · last reviewed 2026-03-01 · Guide

nuclear receptor 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 2026-03-01. Where a claim depends on a specific study, the study is described rather than over-claimed.

Background and Research Context

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.

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.

Detection, Regulation, and Quality Context

Because cardarine is not an approved medicine, no pharmacopeial monograph defines its identity, purity, or storage requirements. Laboratories typically rely on in-house methods and reference standards when testing materials labeled as GW501516. Certificates of analysis may report purity and identity for a specific batch, but their scope varies and they do not guarantee safety or legal status. Independent verification can include high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance, and elemental analysis. The distinction between research chemical labeling and human use is significant because quality standards and oversight differ.

Cardarine can be detected in biological samples and product materials using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method separates compounds by chromatography and identifies them by mass-to-charge transitions, allowing low-level detection in urine or blood. Sample preparation often involves enzymatic hydrolysis, solid-phase extraction, or protein precipitation. Certified reference materials and isotope-labeled internal standards improve quantification. Detection windows depend on metabolism, matrix, and assay sensitivity, so no single universal window applies.

Regulatory treatment of cardarine differs by context and jurisdiction. In competitive sport, the World Anti-Doping Agency lists PPARδ agonists, including GW501516, as prohibited at all times. Outside sport, it lacks approval as a prescription medicine in major drug markets, and products sold for human consumption may be treated as unapproved drugs. Some countries also restrict importation or sale through general consumer protection and medicines laws. These classifications affect availability, testing, and legal risk without establishing therapeutic value.

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.

Cardarine as Investigational PPARδ Agonist

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.

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.

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Identity and Pharmacological Mechanism

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.

Mechanism and Detection

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.

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.

Supporting material

== Enzymatic browning == Polyphenol oxidase is an enzyme found throughout the plant and animal kingdoms, including most fruits and vegetables. PPO has importance to the food industry because it catalyzes enzymatic browning when tissue is damaged from bruising, compression or indentations, making the produce less marketable and causing economic loss. Enzymatic browning due to PPO can also lead to loss of nutritional content in fruits and vegetables, further lowering their value. Because the substrates of these PPO reactions are located in the vacuoles of plant cells damaged mainly by improper harvesting, PPO initiates the chain of browning reactions. Exposure to oxygen when sliced or pureed also leads to enzymatic browning by PPO in fruits and vegetables. Examples in which the browning reaction catalyzed by PPO may be desirable include avocados, prunes, sultana grapes, black tea, and green coffee beans.

== Use as an educational tool == The AIDA software comes with forty educational case scenarios as standard, each of which represents a 'snapshot' of the metabolic status of a typical person with respect to insulin-dependent type 1 diabetes mellitus. It is easy for users to add or create further case scenarios, as required. Examples of the application of AIDA as an educational tool can be found in various published journal articles.

Durham County Council itself became a unitary authority on 1 April 2009, when the seven remaining non-metropolitan districts of the county were abolished and the county council absorbed their functions. The legislation which made the county council a unitary authority allowed the council to omit the word 'County' from its name to become 'Durham Council', but in the event the name 'Durham County Council' was kept. In 2024 a combined authority was established covering Durham, Gateshead, Newcastle upon Tyne, North Tyneside, Northumberland, South Tyneside and Sunderland, called the North East Mayoral Combined Authority. It is chaired by the directly elected Mayor of the North East and oversees the delivery of certain strategic functions across the area.

The "lobe" classification describes lobes that, while originally defined in the fetus, are also visible in gross anatomy, including dissection and when viewed endoscopically. The five lobes are the anterior lobe or isthmus, the posterior lobe, the right and left lateral lobes, and the middle or median lobe.

Flower lotus cultivars are used exclusively for ornamental purpose, producing many flowers and the lowest plant height. The seed production of flower lotus is typically poor regarding yield and quality. Flower types differ in the number of petals (single petals, double petals, or multi-petals) and their colours range from single colour in white, yellow, pink, and red to bi-colour, most often of white petals with pink tips or highlights. One example of a flower lotus is Wanlian. Also known as bowl lotus, wanlians are any miniature cultivars of N. nucifera sized between 5 and 8 centimetres (2.0 and 3.1 in). Bowl lotuses come in various colours and numbers of petals, and they bloom longer than other species of lotus. But together with the rhizome, their seeds are often too small or too hard to be edible. The sacred lotus may be crossed with the yellow lotus to produce interspecific hybrids. A few cultivars have been produced with differing appearances.

Sources: en.wikipedia.org

Notes from published material

Proteinogenic amino acids Cysteine (Cys, C) Methionine (Met or M), an essential amino acid in humans Metabolic products: Cystine, a cysteine dimer, and an oxidation product of cysteine Homocysteine (Hcy) Homocystine, a homocysteine dimer, and an oxidation product of homocysteine Cystathionine, produced by the transsulfuration pathway S-Adenosyl methionine (SAM, SAMe, SAM-e, AdoMet), a common cofactor in methyltransferases S-Adenosyl homocysteine (SAH), a side product of biomethylation by methyltransferases

=== Propaganda === Cyber propaganda is an effort to control information in whatever form it takes, and influence public opinion. It is a form of psychological warfare, except it uses social media, fake news websites and other digital means. In 2018, Sir Nicholas Carter, Chief of the General Staff of the British Army stated that this kind of attack from actors such as Russia "is a form of system warfare that seeks to de-legitimize the political and social system on which our military strength is based". Jowell and O'Donnell (2006) state that "propaganda is the deliberate, systematic attempt to shape perceptions, manipulate cognitions, and direct behavior to achieve a response that furthers the desired intent of the propagandist" (p. 7). The internet is the most important means of communication today. People can convey their messages quickly across to a huge audience, and this can open a window for evil. Terrorist organizations can exploit this and may use this medium to brainwash people. It has been suggested that restricted media coverage of terrorist attacks would in turn decrease the number of terrorist attacks that occur afterwards.

Embryonic HbE Gower 1 (ζ2ε2) present in the normal embryo. HbE Gower 2 (α2ε2) present in the normal embryo. HbE Portland I (ζ2γ2) present in the normal embryo. Fetal HbF/Fetal (α2γ2) dominating during pregnancy and reducing close to zero a few weeks after birth HbA (α2β2) Adult hemoglobin, present in small quantities during pregnancy Adult HbA (α2β2) comprising approximately 97% of adult hemoglobin HbA2 (α2δ2) comprising approximately 3% of adult hemoglobin HbF/Fetal (α2γ2) dominating during pregnancy and reducing close to zero after birth

==== Elimination ==== DMT is eliminated in urine. When DMT is used in combination with a monoamine oxidase inhibitor (MAOI), its metabolism shifts and a greater amount of DMT-N-oxide is excreted relative to deaminated metabolites. The elimination half-life after intravenous injection is 6 to 12 minutes. However, DMT has a biphasic elimination half-life, with the first phase having a half-life of 6 minutes and the second phase having a half-life of 16 minutes.

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.

How is cardarine detected in anti-doping tests?

Anti-doping laboratories typically use LC-MS/MS to detect GW501516 and its metabolites in urine. The method is sensitive and can identify the compound at low concentrations. Detection depends on sample timing, metabolism, and the specific assay.

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