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Cardarine As Investigational Pparδ Agonist — Questions and Answers

By Editorial Desk · published 2026-03-09 · last reviewed 2026-04-26 · Info

The short version of Anti-doping fits in a sentence. The long version — which is the one that helps — is below.

This page was last updated on 2026-04-26 and is reviewed periodically as new material appears.

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.

Cardarine Identity and Mechanism

Cardarine is the common name for GW501516, a synthetic compound studied as a peroxisome proliferator-activated receptor delta agonist. Researchers developed it to explore treatments for lipid disorders and metabolic conditions. It is not an approved medicine in any country. Early clinical work examined changes in HDL cholesterol and triglycerides, but development was discontinued after animal studies raised concerns about cancer. The compound remains available as a research chemical and appears in discussions of performance enhancement.

At the molecular level, GW501516 binds and activates PPARδ, a nuclear receptor that regulates transcription. Activation shifts expression of genes involved in fatty acid oxidation, energy expenditure, and lipid transport in skeletal muscle and liver. Animal studies report increased endurance and altered lipid profiles after exposure. Human data are limited to small trials and do not establish long-term safety or efficacy. PPARδ also has roles in cell proliferation, so the relationship between activation and cancer risk remains an open question.

Published literature on cardarine includes in vitro assays, rodent experiments, and a small number of human studies. Reports describe effects on exercise capacity and lipid metabolism in animals, while human evidence is sparse. Many online descriptions present the compound as a proven endurance aid, a claim not supported by regulatory approval or large clinical trials. Analytical studies focus on identifying the parent compound and its metabolites in biological samples. Important uncertainties include species differences, dose-response relationships, and the relevance of rodent tumor findings to humans.

Cardarine at a glance

PropertyValueNotes
Common synonymsGW501516, GW-501516, GW 501516, endurobolNames vary in research and anti-doping documents.
Chemical classSynthetic PPARδ agonistSmall-molecule nuclear receptor ligand.
CAS Registry Number317318-70-0Identifier commonly associated with GW501516.
AppearanceWhite to off-white powderTypical for purified research material.
SolubilityLow in water; soluble in DMSO and ethanolOrganic solvents are common for laboratory stock solutions.

Background and Regulatory Status

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.

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.

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Detection, Regulation, and Quality Context

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.

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.

Regulation and Analytical Detection

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.

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 Safety Research

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.

Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.

Reference notes

The three substrates of this enzyme are (S)-1-pyrroline-5-carboxylic acid, reduced nicotinamide adenine dinucleotide (NADH), and a proton. Its products are L-proline and oxidised (NAD+). Nicotinamide adenine dinucleotide phosphate can be used as an alternative cofactor. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-proline:NAD(P)+ 5-oxidoreductase. Other names in common use include proline oxidase, L-proline oxidase, 1-pyrroline-5-carboxylate reductase, NADPH-L-Delta1-pyrroline carboxylic acid reductase, and L-proline-NAD(P)+ 5-oxidoreductase. This enzyme participates in arginine and proline metabolism.

The main minority ethnic groups of the former Commonwealth, including Ukrainians, Lithuanians, Belarusians and Jews, were getting involved in their own national movements and plans, which met with disapproval on the part of those Polish independence activists who counted on an eventual rebirth of the Commonwealth or the rise of a Commonwealth-inspired federal structure (a political movement referred to as Prometheism). Around the start of the 20th century, the Young Poland cultural movement, centered in Austrian Galicia, took advantage of a milieu conducive to liberal expression in that region and was the source of Poland's finest artistic and literary productions. In this same era, Marie Skłodowska Curie, a pioneer radiation scientist, performed her groundbreaking research in Paris.

Eventually, explanation what implies "the balance of power favoring freedom" was dropped by "US National Security and Defense Strategies" of 2018: The Pentagon will ensure that the United States remain the "preeminent military power in the world," and the regional "balances of power remain in our favor." [Emphasis added] The "balance of power favoring freedom" appeared identical with the balance of power favoring "us." Russian President Vladimir Putin complained: "Instead of establishing a new balance of power … they [the United States] took steps that threw the [international] system into sharp and deep imbalance." In 1826, George Canning "called the new world into existence to redress the balance of the old". In 1898, Theodore Roosevelt found that the United States had become "more and more the balance of power of the whole globe." In 1941, a New Deal Economist with the National Resources Planning Board, Otto T. Mallery, averred that "destiny offers to the United States the ultimate balance of power and of resources in the world after the war." Colin Gray titled his 2005 chapter by question, "Where Is the Balance of Power?" The chapter opens: "The short answer is that the United States is the balance of power."

Sources: en.wikipedia.org

Reference notes

UR (Uitsluitend Recept): prescription only UA (Uitsluitend Apotheek): pharmacist only UAD (Uitsluitend Apotheek of Drogist): pharmacist or drugstore only AV (Algemene Verkoop): may be sold in general stores A drug that is UA may be sold OTC but only by pharmacists. The drug can be on the shelves like any other product. Examples are domperidone, 400 mg ibuprofen up to 50 tablets and dextromethorphan. A drug that is UAD can also be sold at drugstores which are stores where no prescription can be filled. The drugs are usually on the shelves, and the store also sells items like toys, gadgets, perfumes and homeopathic products. The drugs in this category have limited risk and addiction potential. Examples are naproxen and diclofenac in small amounts, cinnarizine, 400 mg ibuprofen up to 20 tablets and also 500 mg paracetamol up to 50 tablets. Drugs in the AV category can be sold at supermarkets, gas stations, etc. and include only drugs with minimal risk to the public, like paracetamol up to 20 tablets, 200 mg ibuprofen up to 10 tablets, cetirizine and loperamide.

Artificially acquired active immunity can be induced by a vaccine, a substance that contains antigen. A vaccine stimulates a primary response against the antigen without causing symptoms of the disease. The term vaccination was coined by Richard Dunning, a colleague of Edward Jenner, and adapted by Louis Pasteur for his pioneering work in vaccination. The method Pasteur used entailed treating the infectious agents for those diseases, so they lost the ability to cause serious disease. Pasteur adopted the name vaccine as a generic term in honor of Jenner's discovery, which Pasteur's work built upon. In 1807, Bavaria became the first group to require their military recruits to be vaccinated against smallpox, as the spread of smallpox was linked to combat. Subsequently, the practice of vaccination would increase with the spread of war. There are four types of traditional vaccines:

Actinium is a chemical element; it has symbol Ac and atomic number 89. It was discovered by Friedrich Oskar Giesel in 1902, who gave it the name emanium; the element got its name by being wrongly identified with a substance André-Louis Debierne found in 1899 and called actinium. The actinide series, a set of 15 elements between actinium and lawrencium in the periodic table, is named after actinium. Together with polonium, radium, and radon, actinium was one of the first non-primordial radioactive elements to be discovered. A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air, forming a white coating of actinium oxide that prevents further oxidation. As with most lanthanides and many actinides, actinium assumes oxidation state +3 in nearly all its chemical compounds. Actinium is found only in traces in uranium and thorium ores as the isotope 227Ac, which decays with a half-life of 21.772 years, predominantly emitting beta and sometimes alpha particles, and 228Ac, which is beta active with a half-life of 6.15 hours. One tonne of natural uranium in ore contains about 0.2 milligrams of actinium-227, and one tonne of thorium contains about 5 nanograms of actinium-228. The close similarity of physical and chemical properties of actinium and lanthanum makes the separation of actinium from the ore impractical. Instead, the element is prepared, in milligram amounts, by the neutron irradiation of 226Ra in a nuclear reactor. Owing to its scarcity, high price, and radioactivity, actinium has no significant industrial use.

Sources: en.wikipedia.org

Reference notes

Calcium-oxalate-accumulating plants, such as Amaranthus hybridus and Colobanthus quitensis, show a variation of photosynthesis where calcium oxalate crystals function as dynamic carbon pools, supplying carbon dioxide (CO2) to photosynthetic cells when stomata are partially or totally closed. This process was named alarm photosynthesis. Under stress conditions (e.g., water deficit), oxalate released from calcium oxalate crystals is converted to CO2 by an oxalate oxidase enzyme, and the produced CO2 can support the Calvin cycle reactions. Reactive hydrogen peroxide (H2O2), the byproduct of oxalate oxidase reaction, can be neutralized by catalase. Alarm photosynthesis represents a photosynthetic variant to be added to the well-known C4 and CAM pathways. However, alarm photosynthesis, in contrast to these pathways, operates as a biochemical pump that collects carbon from the organ interior (or from the soil) and not from the atmosphere.

After the 1921 season, the East Melbourne Cricket Ground was closed and demolished to expand the Flinders Street Railyard. Having played at the East Melbourne Cricket Ground from 1882 to 1921, and having won four VFA premierships (1891–1894) and four VFL premierships (1897, 1901, 1911 and 1912) while there, Essendon was looking for a new home. It was offered grounds at the current Royal Melbourne Showgrounds, Ascot Vale; at Victoria Park, Melbourne; at Arden St, North Melbourne; and the Essendon Cricket Ground. The Essendon City Council offered the (VFL) team the Essendon Cricket Ground, announcing that it would be prepared to spend over £12,000 (equivalent to A$2,159,104 in 2022) on improvements, including a new grandstand, scoreboard and re-fencing of the oval. The club's first preference was to move to North Melbourne—a move which the North Melbourne Football Club (then in the VFA) saw as an opportunity to get into the VFL. Most of Essendon's members and players were from the North Melbourne area, and sportswriters believed that Essendon would have been taken over by or rebranded as North Melbourne within only a few years of the move. However, the VFA, desperate for its own strategic reasons not to lose its use of the North Melbourne Cricket Ground, successfully appealed to the State Government to block Essendon's move to North Melbourne. With its preferred option off the table, the club returned to Essendon, and the Essendon VFA club disbanded, with most of its players moving to North Melbourne.

=== Routes for topical drug administration === In general, there are three possible routes for drug administration into or across the skin. The first one is the transcellular route, where the drugs are required to pass through both lipid matrix and dead corneocytes of the stratum corneum. The second one is the intercellular route, where the drugs only have to pass through lipid domains between corneocytes. The third one is the trans-appendageal route, where the drugs are transported by hair follicles, sebaceous glands, or sweat glands. The most common route for drug delivery into the skin is the intercellular route. Multiple steps are involved.

=== Gel electrophoresis === Gel electrophoresis has been used in attempts to identify the amino acids present in the organic components of dinosaur eggshell. Contact with human skin can contaminate eggs with foreign amino acids, so only untouched eggs can be investigated using this technique. EDTA can be used to dissolve the calcite of the eggshell while leaving the shell's organic content intact. The resultant organic residue would be blended and then implanted into gel. Electricity would then be run through the sample, causing the amino acids to migrate through the gel until they stop at levels determined by their physical properties. Protein silver stain is then used to dye the amino acids and make them visible. The bands of amino acids from the dinosaur eggs can then be compared with the banding of samples with known composition for identification. Gel electrophoresis is not necessarily a perfect means of discovering the amino acid composition of dinosaur eggshell because sometimes the amount or type of amino acids present could be altered during or after preservation. One potential confounding factor would be the heating of deeply buried egg fossils, which can break down amino acids. Another potential source of error is groundwater, which can leach away amino acids. These issues cast doubt as to whether the results these sorts of studies give are reliable as the actual composition of the eggshell's organic material in life.

Sources: en.wikipedia.org

Frequently asked questions

What is cardarine?

Cardarine is an investigational synthetic compound that acts as a PPARδ agonist. It is also known as GW501516 and has been studied mainly in preclinical research. It is not an approved medicine.

Is cardarine a steroid?

No. Cardarine is not a steroid hormone; it targets the nuclear receptor PPARδ. Its classification in anti-doping rules differs from anabolic steroids, though it remains prohibited in sport.

Why was cardarine not developed further?

Early rodent studies reported tumor formation at multiple sites, which raised safety concerns. Sponsors stopped clinical development, and no approved human product exists.

What is cardarine?

Cardarine is a common name for the investigational compound GW501516. It acts as a PPARδ agonist and is not approved for human use. It is prohibited in sport.

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