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Background And Regulatory Status — Common Mistakes

By Editorial Desk · published 2025-08-10 · last reviewed 2025-08-24 · Faq

Everything below concerns anti-doping. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.

Updated 2025-08-24. Numbers and descriptions here follow the published literature rather than marketing material.

Background and Regulatory Status

Legal status varies by country. In some places, cardarine is controlled under medicines or psychoactive substances laws; in others, it may be sold with minimal oversight as a research chemical. Customs agencies have intercepted shipments, and several national health agencies have issued warnings about products marketed for bodybuilding or performance enhancement. The lack of a standardized pharmaceutical supply means identity, purity, and contamination levels can differ widely between samples. These factors make cardarine a regulatory and public health concern rather than a conventional prescription drug.

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.

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 at a glance

PropertyValueNotes
IUPAC name{4-[({4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-5-yl}methyl)sulfanyl]phenoxy}acetic acidSystematic name for GW501516
CAS Registry Number317318-70-0Unique identifier for the parent compound
Molecular formulaC21H18F3NO3S2Includes carbon, hydrogen, fluorine, nitrogen, oxygen, and sulfur
Molecular weight453.5 g/molApproximate value for the neutral form
AppearanceWhite to off-white powderTypical description for purified laboratory material

Mechanism and Detection Methods

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.

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.

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Mechanism and Detection

Preclinical research reported that GW501516 increased running endurance in mice and improved lipid profiles in some animal species. Early human trials explored effects on high-density lipoprotein cholesterol, triglycerides, and glucose handling, but the program was discontinued. Published human data are sparse and do not establish efficacy for any condition. Studies also examined PPAR delta in cancer biology, with conflicting findings across models. The relationship between receptor activation, tissue context, and disease risk remains an active area of investigation.

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.

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.

Further detail

March 14: A decree provides that Chambers of Commerce and Consultative Chambers of Arts and Manufacturing include women among both voters and eligible candidates. April 3: Law modifying Articles 334 and 335 of the Penal Code and Articles 5 and 7 of the Code of Criminal Procedure; notably amends provisions relating to pimping, the corruption of minors, incitement to debauchery, corruption of youth, and international trafficking. December 15, 1904: Abolition of the ban on marrying the "accomplice in adultery." February 7, 1905: Decree implementing the international agreement aimed at effectively protecting against the criminal trade known as "white slavery" (international agreement from May 1904). 1907

Striated muscle tissue is a muscle tissue that features repeating functional units called sarcomeres. Under the microscope, sarcomeres are visible along muscle fibers, giving a striated appearance to the tissue. The two types of striated muscle are skeletal muscle and cardiac muscle.

== Detection and optical properties == A spectral database exists for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe. Detection of PAHs in materials is often done using gas chromatography-mass spectrometry or liquid chromatography with ultraviolet-visible or fluorescence spectroscopic methods or by using rapid test PAH indicator strips. Structures of PAHs have been analyzed using infrared spectroscopy. PAHs possess very characteristic UV absorbance spectra. These often possess many absorbance bands and are unique for each ring structure. Thus, for a set of isomers, each isomer has a different UV absorbance spectrum than the others. This is particularly useful in the identification of PAHs. Most PAHs are also fluorescent, emitting characteristic wavelengths of light when they are excited (when the molecules absorb light). The extended pi-electron electronic structures of PAHs lead to these spectra, as well as to certain large PAHs also exhibiting semi-conducting and other behaviors.

==== March ==== On 13 March, the Syrian government forces launched attacks toward Suwayda, Syrian government forces in Kharbat Samar attacked residents in the city of Ara. On 19 March, clashes erupted between Syrian government forces and local defense units, including the Syrian National Guard, on multiple fronts around Suwayda, encompassing Tal Hadid and villages such as Walgha and Mansoura, and involving heavy and medium weaponry. A day later, Israeli airstrikes targeted several positions of Syrian government forces at Izraa in Daraa Governorate, including command and control centres, supply depots, and facilities held by the 40th Battalion of the Syrian Army, in retaliation to the escalation of hostilities. On 25 March, a National Guard member was injured during clashes in the city of Era, in southern Suwayda.

Sources: en.wikipedia.org

Supporting material

==== Omission libraries ==== In omission libraries, a certain amino acid is missing from all peptides of the mixture. The figure shows the full library and the three omission libraries. At the top, the omitted amino acids are shown. If the omission library gives a negative test, the omitted amino acid is present in the active component.

Most paleontologists have always accepted that Tyrannosaurus was an active predator and, like most large carnivores, would also opportunistically scavenge. By far the largest carnivore in its environment, T. rex was most likely an apex predator, preying upon hadrosaurs, armored herbivores like ceratopsians and ankylosaurs, and possibly sauropods (such as Alamosaurus). Enamel δ44/42Ca values also suggest the possibility that T. rex occasionally fed on carcasses of marine reptiles and fish washed up on the shores of the Western Interior Seaway. A study in 2012 by Karl Bates and Peter Falkingham found that Tyrannosaurus had the most powerful bite of any terrestrial animal that has ever lived, finding an adult Tyrannosaurus could have exerted 35,000 to 57,000 N (7,868 to 12,814 lbf) of force in the back teeth. Even higher estimates were made by Mason B. Meers in 2003. This allowed it to crush bones during repetitive biting and fully consume the carcasses of large dinosaurs. Stephan Lautenschlager and colleagues calculated that Tyrannosaurus was capable of a maximum jaw gape of around 80 degrees, a necessary adaptation for a wide range of jaw angles to power the creature's strong bite. A discredited fringe hypothesis that was never seriously considered was that Tyrannosaurus was an obligate scavenger. The argument originated in a 1917 study by Lambe which argued that large theropods were pure scavengers because Gorgosaurus teeth showed hardly any wear. This argument disregarded the fact that theropods rapidly replaced their teeth.

As a result, it is often combined with these drugs to reduce their side-effect profile and to produce a stronger antidepressant effect. Mirtazapine does not have pro-serotonergic activity and thus does not cause serotonin syndrome. This is in accordance with the fact that it is not a serotonin reuptake inhibitor or monoamine oxidase inhibitor, nor a serotonin receptor agonist. There are no reports of serotonin syndrome in association with mirtazapine alone, and mirtazapine has not been found to cause serotonin syndrome in overdose. However, there are a handful of case reports of serotonin syndrome occurring with mirtazapine in combination with serotonergic drugs like selective serotonin reuptake inhibitors, although such reports are very rare, and do not necessarily implicate mirtazapine as causative.

== Medical uses == Succimer is sold under the brand name Chemet among others. It is a medication tool used to treat lead, mercury, and arsenic poisoning. When radiolabeled with technetium-99m, it is used in many types of diagnostic testing. Common side effects include vomiting, diarrhea, rash, and low blood neutrophil levels. Liver problems and allergic reactions may also occur with use. Whether use during pregnancy is safe for the baby is unclear. Dimercaptosuccinic acid is in the chelating agent family of medications. It binds to a metal atom, leading to increased clearance from the body via the urine. A full course of Succimer lasts for 19 days of oral administration. A second course should be given after more than two weeks break after the first course. Succimer has been used medically since the 1950s. It is on the World Health Organization's List of Essential Medicines. In the United States, no generic version was available as of 2015.

==== Molecular and signaling response to LTP-inducing stimuli ==== The mechanism for LTP has long been a topic of debate, but, recently, mechanisms have come to some consensus. AMPARs play a key role in this process, as one of the key indicators of LTP induction is the increase in the ratio of AMPAR to NMDARs following high-frequency stimulation. The idea is that AMPARs are trafficked from the dendrite into the synapse and incorporated through some series of signaling cascades. AMPARs are initially regulated at the transcriptional level at their 5' promoter regions. There is significant evidence pointing towards the transcriptional control of AMPA receptors in longer-term memory through cAMP response element-binding protein (CREB) and mitogen-activated protein kinases (MAPK). Messages are translated on the rough endoplasmic reticulum (rough ER) and modified there. Subunit compositions are determined at the time of modification at the rough ER. After post-ER processing in the Golgi apparatus, AMPARs are released into the perisynaptic membrane as a reserve waiting for the LTP process to be initiated. The first key step in the process following glutamate binding to NMDARs is the influx of calcium through the NMDA receptors and the resultant activation of Ca2+/calmodulin-dependent protein kinase (CaMKII). Blocking either this influx or the activation of CaMKII prevents LTP, showing that these are necessary mechanisms for LTP. In addition, profusion of CaMKII into a synapse causes LTP, showing that it is a causal and sufficient mechanism.

Sources: en.wikipedia.org

Notes from published material

The ash content of a sample is a measure of the amount of inorganic noncombustible material it contains. The residues after a sample is completely burnt - in contrast to the ash remaining after incomplete combustion - typically consist of oxides of the inorganic elements present in the original sample. Ash is one of the components in the proximate analysis of biological materials, consisting mainly of salty, inorganic constituents. It includes metal salts which are important for processes requiring ions such as Na+ (sodium), K+ (potassium), and Ca2+ (calcium). It also includes trace minerals which are required for unique molecules, such as chlorophyll and hemoglobin. Procedures for ash content determination are similar to procedures for loss on ignition. Typically, the term ash is used for primarily organic material such as fuels and foodstuffs, while the term loss on ignition is used for primarily inorganic material such as rocks and combusted ash. A crucible can be used to determine the percentage of ash contained in a sample of material such as coal, wood, oil, rubber, plastics, foodstuffs, or any burnable material. The appropriate method for ash determination varies depending upon the type of sample analyzed. Each method may vary in parameters such as furnace temperature, residence time in the furnace, number of heating steps, and sample preparation procedures. The ISO mandates ash content determination for most foodstuffs. Examples include

Boiled potatoes. Take a thoroughly washed potato and boil it in water; when it is ready, it needs to be cleaned, cut, greased with butter and pepper. (French: Tartoufle boullye. Prennez tartoufle bien lauee, & la mettez boullir dedans eau, eſtant cuite il la faut peler & coupper par tranches, beurre fondu par deſſus, & poiure.)

=== Mechanical === Friable macro- or micro-scale solid particles can be ground in a ball mill, a planetary ball mill, or other size-reducing mechanism until enough of them are in the nanoscale size range. The resulting powder can be air classified to extract the nanoparticles.

=== 19 kDa Protein === This catalytic component of OpLuc has 196 amino acids with one cysteine in the carboxyl terminus and is distinct from proteins found in other luciferases. The protein is made up of two domains with repetitive sequencing of Ia-c and Ila-d in the peptide chain. It is thought to be the protein to cause the bioluminescent reaction of O.gracilirostris, but functions ineffectively without its larger, subunit counterpart. Although the crystal structure of OpLec has yet to be completely analyzed and mapped, 19 kDa experimentally expressed in mammalian cells (regarded as KAZ). The protein was isolated and mutated to catalyze a bright and sustained luminescent reaction to create an engineered luciferase, NanoLuc (NLuc), and a coelenterazine analogue (furimazine) to be used as a cellular reporter. Additional substrates with increased aqueous solubility (hydrofurimazine, fluorofurimazine, cephalofurimazine, and cephalofurimazine-9) were later developed.

Sources: en.wikipedia.org

Frequently asked questions

Is cardarine approved for human use?

No. Major drug regulators have not approved GW501516 for treating any medical condition. Products sold as cardarine are typically unapproved research chemicals or supplements, so their contents and safety are not assured.

Why is cardarine banned in sport?

It is prohibited by the World Anti-Doping Agency as a hormone and metabolic modulator. Athletes who test positive for GW501516 can face sanctions, including suspensions and loss of results.

What is the difference between cardarine and GW501516?

Cardarine is a common or trade-style name, while GW501516 is the research code for the same chemical entity. Some sources also use Endurobol or GSK-516. The names refer to the same compound, not distinct drugs.

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.

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