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Background And Regulatory History — Quick Reference

By Editorial Desk · published 2026-01-03 · last reviewed 2026-01-22 · Data

GW501516 raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.

Reviewed 2026-01-22. Anything still debated is marked as such rather than presented as settled.

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 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.

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.

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 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.

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.

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Mechanism and Detection Methods

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.

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.

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.

Published studies have examined GW501516 in animal models of obesity, insulin resistance, and exercise endurance. Early human trials reportedly ended, and development was discontinued after preclinical findings raised concerns about cancer in some rodent studies. Regulatory agencies have not approved cardarine for any medical use. Its availability through non-pharmaceutical channels raises questions about identity, purity, and legal status that are separate from its laboratory pharmacology. Those questions are often addressed through analytical testing rather than assumptions about product labels.

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.

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.

Supporting material

Arrhenius acid Any substance that, when dissolved in water, increases the concentration of H+ ions, or, more correctly, of hydronium ions (H3O+), in the resulting aqueous solution. The definition is similar to that of a Brønsted–Lowry acid. Contrast Arrhenius base.

Graham Thomas Waters. Founder and Managing Director, Airbond. For services to Innovation. Selina Marie Webb. Executive Vice President, Universal Music UK. For services to the Music Industry, to Neurodiversity and to Charity. Maurice Scott Weightman. Founding Chair and Trustee, Berwick Youth Project. For services to Young People in Berwick-Upon-Tweed. Arabella Helen Weir. Artistic Director, Kirkcaldy Festival of Ideas and Trustee, Theirworld Children's Charity. For services to the Arts and to Young People. James Michael Whale. Broadcaster. For services to Broadcasting and to Charity. Anne Patricia White. Volunteer Director, Thurrock Lifestyle Solutions Community Interest Company. For services to People with Impairments. Jonathan Richard White. Economist, Department of Health and Social Care. For services to Social Care Policy. Claire Amanda Whiting. Founder, Two2One. For services to Bereaved People in Southend-on-Sea, Essex. Carly Ann Whyborn. Director, Refugees at Home. For services to Refugees. Carla Maria Williams (Carla Marie Williams). Chief Executive Officer and Founder, Girls I Rate and Songwriter. For services to Music. Dr. Elizabeth Catherine Williams (Kay Williams). Head of International Chemicals, Pesticide and Hazardous Waste, Department for Environment, Food and Rural Affairs. For services to the International Environment and charitable service through Bees Abroad. Gareth David Williams. Detective Superintendent, British Transport Police. For services to Policing. Joanne Kate Williams (Kate Woolveridge). Chief Executive Officer, Forget-me-not Chorus.

== Litigation == CLIA itself has not been the subject of much litigation. Federal district courts have held that the CLIA did not create a private cause of action for individuals to sue laboratories that do not comply with its provisions.

Sources: en.wikipedia.org

Supporting material

At the height of the pandemic in mid-2021, the Philippines was a COVID-19 hotspot in Asia; vaccine hesitancy was a problem, and many citizens opted to wait for Western vaccines to arrive. In exasperation, Duterte urged the public to undergo vaccination, threatening to arrest unvaccinated individuals and order local leaders to compile a list of defiant residents. In May 2021, to encourage the public that vaccines were safe, Duterte—acting on the advice of his doctor—publicly took the Sinopharm BIBP vaccine before it was approved for use by the Philippine Food and Drug Administration; his move, however, drew criticism since the general public had access to CoronaVac vaccines, which the public majority perceived to have lower efficacy. The backlash prompted Duterte to apologize, acknowledge the possibility of the Sinopharm vaccine's multiple side effects, and decide to pull out the vaccines. The public's prejudice against China's CoronaVac was later revealed in a Reuters 2024 report as the outcome of a US government-launched covert propaganda and disinformation campaign that aimed to erode the public's trust in China-developed vaccines. Duterte gradually relaxed quarantine restrictions to revive the economy. Upon leaving office, Duterte's administration secured 245 million vaccine doses; about 70.5 million individuals had been fully vaccinated. Over 3.7 million COVID-19 cases were recorded since the onset of the pandemic, 3.69 million people had recovered from the disease, while 8,706 active cases remained.

=== Magic Pill (2024) === Magic Pill: The Extraordinary Benefits and Disturbing Risks of the New Weight Loss Drugs, Hari's first-person account of taking the weight loss drug Ozempic (semaglutide), was published in 2024. The book also documents the history of the medication. According to Hari, while there are health benefits to taking Ozempic for some users, there are also potential risks. Hari falsely claimed in Magic Pill that restaurant critic Jay Rayner had taken semaglutide and the book included false statements about Rayner's opinion of the drug. Rayner had previously written that he would never take the drug, and described Hari's description as "very much defamatory". Hari apologized for the error. In a review for The Guardian, science writer Tom Chivers found several misuses of references that did not support the book's claims, as well as scientific inaccuracies. A fact check by The Daily Telegraph found six examples of "errors, outdated data and disputed claims". Hari said these errors would be corrected in future editions. Magic Pill has been translated into French and Russian.

Progesterone is available in a variety of different forms, including oral capsules; sublingual tablets; vaginal capsules, tablets, gels, suppositories, and rings; rectal suppositories; oil solutions for intramuscular injection; and aqueous solutions for subcutaneous injection. A 1% topical progesterone gel is approved for local application to the breasts to treat breast pain, but is not indicated for systemic therapy. Progesterone was previously available as an intrauterine device for use in hormonal contraception, but this formulation was discontinued. Progesterone is also limitedly available in combination with estrogens such as estradiol and estradiol benzoate for use by intramuscular injection. In addition to approved pharmaceutical products, progesterone is available in unregulated custom compounded and over-the-counter formulations like systemic transdermal creams and other preparations. The systemic efficacy of transdermal progesterone is controversial and has not been demonstrated.

Sources: en.wikipedia.org

Notes from published material

== Side effects == Common adverse reactions include nausea, headache, fatigue, vomiting, diarrhea, Anorexia (symptom) (loss of appetite), and insomnia (trouble sleeping). Rare but serious side effects include hypersensitivity reaction such as rash, elevated AST and ALT, depression, anxiety, fever/chills, URI, lactic acidosis, hypertriglyceridemia, and lipodystrophy.

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The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages: the cephalic phase, the gastric phase, and the intestinal phase. The first stage, the cephalic phase of digestion, begins with secretions from gastric glands in response to the sight and smell of food, and continues in the mouth with the mechanical breakdown of food by chewing, and the chemical breakdown by digestive enzymes in the saliva. Saliva contains amylase, and lingual lipase, secreted by the salivary glands, and serous glands on the tongue. Chewing mixes the food with saliva to produce a food bolus to be swallowed down the esophagus to enter the stomach. The second stage, the gastric phase, takes place in the stomach, where the food is further broken down by mixing with gastric juice until it passes into the duodenum, the first part of the small intestine. The intestinal phase where the partially digested food is mixed with pancreatic digestive enzymes completes the process of digestion. Digestion is helped by the chewing of food carried out by the muscles of mastication, the tongue, and the teeth, and also by the contractions of peristalsis, and segmentation. Gastric juice containing gastric acid, and the production of mucus in the stomach, are essential for the continuation of digestion.

They selected a site where the Italian trenches were sheltered in a deep valley so that a gas cloud would persist. The following Battle of Caporetto broke the Italian lines, and the Central Powers overran much of northern Italy. That summer Hahn was accidentally poisoned by phosgene while testing a new model of gas mask. At the end of the war he was in the field in mufti on a secret mission to test a pot that heated and released a cloud of arsenicals.

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.

How is cardarine detected in samples?

Anti-doping and clinical laboratories commonly use liquid chromatography-tandem mass spectrometry. The method can identify GW501516 and its metabolites in urine or blood. Detection depends on sample timing and the amount present.

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