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Background And Regulatory History — What the Evidence Shows

By Editorial Desk · published 2025-06-28 · last reviewed 2025-07-12 · Faq

If you have been reading about anti-doping and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.

Updated 2025-07-12. Numbers and descriptions here follow the published literature rather than marketing material.

Background and Regulatory History

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.

Regulatory bodies treat GW501516 as a prohibited substance in competitive sport. The World Anti-Doping Agency added it to the prohibited list, and it falls under classes covering metabolic modulators and hormone-related agents. It is not approved by drug regulators for human use, and it is not a lawful dietary supplement. Products sold under the cardarine name may contain unlisted ingredients or different compounds. Because no approved product exists, quality and identity are not guaranteed by pharmaceutical manufacturing standards.

Cardarine as Investigational PPARδ Agonist

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.

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.

Cardarine at a glance

PropertyValueNotes
Common nameCardarineCommon internet and media name.
Research codeGW501516Also written GW-1516.
Drug classPPARδ agonistNot a selective androgen receptor modulator.
Development statusDiscontinuedClinical development halted after rodent cancer findings.
Regulatory statusProhibited in sportListed by WADA; not approved as medicine.

Regulation and Detection

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.

Cardarine is frequently described as a fat-burning or endurance-enhancing supplement, but these claims exceed the available evidence. The compound is not a hormone, steroid, or selective androgen receptor modulator. Research articles discuss it as a tool compound for studying PPARδ biology, while anti-doping literature focuses on its abuse and detection. Quality of unapproved products is uncertain, and independent analyses have found impurities or incorrect labeling. Open questions include whether human cancer risk resembles that seen in rodents and how often non-athletes use the substance.

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Identity and Pharmacological Classification

Cardarine is a common name for GW501516, also GW-1516, a synthetic compound developed as a peroxisome proliferator-activated receptor delta (PPARδ) agonist. It belongs to a class of agents that modulate gene transcription related to lipid and energy metabolism. The compound was studied in preclinical and early clinical research for metabolic and cardiovascular conditions, but it did not progress to approved therapeutic use. Its name appears in fitness and sports contexts despite not being approved as a drug.

PPARδ is a nuclear receptor that influences transcription of genes involved in fatty acid oxidation, lipid transport, and energy homeostasis. GW501516 binds and activates this receptor with high selectivity relative to PPARα and PPARγ in laboratory assays. Activation alters expression of target genes in skeletal muscle, liver, and adipose tissue in animal models. The exact clinical consequences of these changes in humans remain incompletely characterized, and observed effects in animals do not establish therapeutic benefit or safety.

Regulation and Analytical Detection

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.

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.

Notes from published material

Isotretinoin, also known as 13-cis-retinoic acid and sold under the brand name Accutane among others, is a medication used to treat skin diseases like harlequin-type ichthyosis, lamellar ichthyosis, and severe cystic acne or moderate acne that is unresponsive to antibiotics. Isotretinoin is used off-label to treat basal cell carcinoma and squamous cell carcinoma, although clinical evidence suggests it is not effective in this setting. It is a retinoid, meaning it is related to vitamin A, and is found in small quantities naturally in the body. Its isomer, tretinoin, is also an acne drug. In its pure form, isotretinoin is an orange powder. The most common adverse effects are dry lips (cheilitis), dry and fragile skin (xeroderma), dry eyes and an increased susceptibility to sunburn. Uncommon and rare side effects include muscle aches and pains (myalgias), headaches, and depression in some users. Some of those side effects can persist long after the discontinuation of the use of the drug. Isotretinoin may cause liver failure, therefore the patient's blood levels should be regularly tested. It is known to cause birth defects due to in-utero exposure because of the molecule's close resemblance to retinoic acid, a natural vitamin A derivative that controls normal embryonic development. It is associated with psychiatric side effects, most commonly depression, and more rarely, psychosis and unusual behaviors. Other rare side effects include hyperostosis and premature epiphyseal closure, which have been reported to be persistent.

On entering puberty, the penis, scrotum and testicles will enlarge toward maturity. During the process, pubic hair grows above and around the penis. A large-scale study assessing penis size in thousands of 17- to 19-year-old males found no difference in average penis size between 17-year-olds and 19-year-olds. From this, it can be concluded that penile growth is typically complete not later than age 17, and possibly earlier.

=== Research on hemophilia gene therapy === High was a faculty member at the University of North Carolina - Chapel Hill for seven years, where she started her career by cloning the normal canine Factor IX gene and then characterizing the mutation in a naturally occurring canine model of hemophilia B, to enable gene therapy studies for the disease in a canine model. She also identified several mutations responsible for human hemophilia B, as well as Factor VII, and Factor X-deficient blood clotting disorders. High moved to the University of Pennsylvania and Children's Hospital of Philadelphia, where she began pioneering clinical trials of gene therapy for blood disorders. During her career at the University of Pennsylvania, High expanded her research into gene therapy solutions for hereditary blindness together with Dr. Jean Bennett. She was the director of the Center for Cellular and Molecular Therapeutics, and beginning in 2001, head of hematology research, at the Children's Hospital of Philadelphia, where she was also an investigator of the Howard Hughes Medical Institute.

Molybdenum is the 54th most abundant element in the Earth's crust with an average of 1.5 parts per million and the 25th most abundant element in the oceans, with an average of 10 parts per billion; it is the 42nd most abundant element in the Universe. The Soviet Luna 24 mission discovered a molybdenum-bearing grain (1 × 0.6 μm) in a pyroxene fragment taken from Mare Crisium on the Moon. The comparative rarity of molybdenum in the Earth's crust is offset by its concentration in a number of water-insoluble ores, often combined with sulfur in the same way as copper, with which it is often found. Though molybdenum is found in such minerals as wulfenite (PbMoO4) and powellite (CaMoO4), the main commercial source is molybdenite (MoS2). Molybdenum is mined as a principal ore and is also recovered as a byproduct of copper and tungsten mining. The world's production of molybdenum was 250,000 tonnes in 2011, the largest producers being China (94,000 t), the United States (64,000 t), Chile (38,000 t), Peru (18,000 t) and Mexico (12,000 t). The total reserves are estimated at 10 million tonnes, and are primarily concentrated in China (4.3 Mt), the US (2.7 Mt) and Chile (1.2 Mt). By continent, 93% of the world's molybdenum production is distributed approximately evenly among North America, South America (mainly Chile), and China. Europe and the rest of Asia (mostly Armenia, Russia, Iran and Mongolia) produce the remainder.

Another turning point in this timeframe for Dick is the alleged burglary of his home and theft of his papers. After delivering "The Android and the Human", Dick became a participant in X-Kalay (a Canadian Synanon-type recovery program), effortlessly convincing program caseworkers that he was nursing a heroin addiction to do so. Dick's recovery program participation was portrayed in the posthumously released book The Dark Haired Girl (a collection of letters and journals from this period, most of a romantic nature). It was at X-Kalay, while doing publicity for the facility, that he devised the notion of rehab centers being used to secretly harvest drugs (thus inspiring the book's New-Path clinics). In the afterword, Dick dedicates the book to those of his friends—he includes himself—who had experienced debilitation or death as a result of their drug use. Mirroring the epilogue are the involuntary goodbyes that occur throughout the story—the constant turnover and burn-out of young people that lived with Dick during those years. In the afterword, he states that the novel is about "some people who were punished entirely too much for what they did", and that "drug misuse is not a disease, it is a decision, like the decision to move out in front of a moving car".

Sources: en.wikipedia.org

Further detail

=== Hair loss === LLLT has been studied as a treatment for hair loss; a review in 2012 found little evidence to support the use of lasers to treat hair loss. A 2014 review found tentative evidence for benefit for lasers, while another 2014 review concluded that the results were mixed, had a high risk of bias, and that its effectiveness was unclear. A 2015 review found tentative evidence of benefit. Additionally, a 2017 review of clinical trials found 10 of 11 trials reviewed "demonstrated significant improvement of androgenic alopecia in comparison to baseline or controls when treated with LLLT." LLLT is shown to increase hair density and growth in both genders. The types of devices (hat, comb, helmet) and duration did not alter the effectiveness, with more emphasis to be placed on lasers compared to LEDs. Ultraviolet and infrared light are more effective for alopecia areata, while red light and infrared light is more effective for androgenetic alopecia. Medical reviews suggest that LLLT is as effective or potentially more than other non invasive and traditional therapies such as minoxidil and finasteride but further studies such as RCTs, long term follow up studies, and larger double blinded trials need to be conducted to confirm the initial findings.

In 2022 global production of sugar beets was 260 million tonnes, led by Russia with 18.8% of the world total (table). Sugar beet became a major source of sugar in the 19th century when methods for extracting the sugar became available. It is a biennial plant, a cultivated variety of Beta vulgaris in the family Amaranthaceae, the tuberous root of which contains a high proportion of sucrose. It is cultivated as a root crop in temperate regions with adequate rainfall and requires a fertile soil. The crop is harvested mechanically in the autumn and the crown of leaves and excess soil removed. The roots do not deteriorate rapidly and may be left in the field for some weeks before being transported to the processing plant where the crop is washed and sliced, and the sugar extracted by diffusion. Milk of lime is added to the raw juice with calcium carbonate. After water is evaporated by boiling the syrup under a vacuum, the syrup is cooled and seeded with sugar crystals. The white sugar that crystallises can be separated in a centrifuge and dried, requiring no further refining.

Following trial and conviction at Wood Green Crown Court, Patrick Simms is sentenced to nine years in prison for the rape of a 15-year-old girl he committed after meeting the girl at a leisure centre in Hackney in 1987. 22 July – Seb Dance, the Deputy Mayor of London, confirms that day travelcards will be phased out for travel within London. 23 July – Newcastle's Northern Pride is forced to end early after heavy rain makes the festival site unsafe. 24 July – The Metropolitan Police announce that radical preacher Anjem Choudary has been charged with three terror offences. 25 July – Data published by the Department for Levelling Up, Housing and Communities indicates the number of homeless people to be at a 25-year high, with 105,000 households in England living in temporary accommodation, a figure that includes 131,000 children. Data released by the Metropolitan Police indicates that a 13-week campaign by Just Stop Oil has cost the force £7.7m to police. 26 July – The Court of Appeal overturns the 2004 conviction of Andrew Malkinson, convicted of a 2003 rape in Salford on unreliable evidence. 27 July – The UK government confirms that COVID-19-era licencing rules in England allowing pubs to sell takeaway drinks will end on 30 September. 28 July – The High Court rules that the planned extension of London's Ultra Low Emission Zone is lawful after rejecting a legal challenge from five Conservative-led local authorities.

=== Analytical implementations === Surface plasmon resonance can be implemented in analytical instrumentation. SPR instruments consist of a light source, an input scheme, a prism with analyte interface, a detector, and computer. Any quantitative derivation relies on modelling the surface based on the boundary conditions of the Maxwell's equations, for plane films using the Fresnel equations.

Sources: en.wikipedia.org

Frequently asked questions

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.

Why did clinical development stop?

Preclinical rodent studies reported cancers, including liver and bladder tumors, at tested doses. The human relevance of those findings is uncertain, but development was discontinued. No approved human product resulted.

Is cardarine approved for medical use?

No. It remains an investigational compound without approved therapeutic labeling. Sports regulators prohibit its use, and health agencies have warned against consuming it.

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.

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