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Background And Regulatory Status — Reference Sheet

By Editorial Desk · published 2026-03-22 · last reviewed 2026-04-09 · Info

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

This page was last updated on 2026-04-09 and is reviewed periodically as new material appears.

Background and Regulatory Status

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.

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.

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

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.

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.

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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.

Mechanism and Laboratory Detection

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.

Laboratory handling focuses on identity, purity, and stability. Reference standards are typically stored cold and dry, protected from light, because solutions can degrade over time. Analytical checks may use high-performance liquid chromatography with ultraviolet detection or mass spectrometry. Impurities and related substances can be separated chromatographically and compared with a known standard. Because cardarine is not an approved drug, compendial monographs are absent, and laboratories often rely on in-house methods. Reported purity varies among unregulated products and should not be assumed from a label.

Notes from published material

=== Post-translational regulation === Interactions of cMyBP-C with its binding partners vary with its posttranslational modification status. At least three extensively characterized phosphorylation sites (Ser273, 282 and 302; numbering refers to the mouse sequence) are localized in the M motif of cMyBP-C and are targeted by protein kinases in a hierarchical order of events. In its dephosphorylated state, cMyBP-C binds predominantly to myosin S2 and brakes crossbridge formation, however, when phosphorylated in response to β-adrenergic stimulation through activating cAMP-dependent protein kinase (PKA), it favours binding to actin, then accelerating crossbridge formation, enhancing force development and promoting relaxation. Protein kinases identified thus far to phosphorylate cMyBP-C in the M motif are PKA, Ca2+/calmodulin-dependent kinase II (CaMKII), ribosomal s6 kinase (RSK), protein kinase D (PKD), and protein kinase C (PKC). Furthermore, GSK3β was described as another protein kinase to phosphorylate cMyBP-C outside the M-domain in the proline-alanine-rich actin-binding site at Ser133 in human myocardium (mouse Ser131). Phosphorylation is required for normal cardiac function and cMyBP-C stability, and overall phosphorylation levels of cMyBP-C are reduced in human and experimental heart failure. Other posttranslational modifications of cMyBP-C exist, which occur throughout the protein and are not thoroughly characterised yet, such as acetylation, citrullination, S-glutathiolation, S-nitrosylation and carbonylation.

boiling flask Also Florence flask. A type of flask, usually made of glass, with a large round body, long neck, and flat bottom, designed especially for heating, boiling, and distilling liquids and to make swirling easy. See also round-bottom flask.

Sam Camfield. Design Manager, South Western Railway. For services to the State Funeral of Her Majesty Queen Elizabeth II. William Wright Glover Campbell. Captain, 1st Stewarton Boys' Brigade. For services to the community in Stewarton, East Ayrshire. Bronwin Mary Carter. Paralympic Coach. For services to Sport. Christopher Charles Cassidy. Watchkeeper, Cabinet Office. For services to Civil Contingencies and to St John Ambulance. Ann Chapman. For services to the community in Radcliffe, Metropolitan Borough of Bury. Stephen Charnock. For services to the community in Newark, Nottinghamshire. Ian Raymond Clark. For services to the community in High Wycombe, Buckinghamshire. Roy Michael Claxton. Founder, Parkinson's Scottish Table Tennis Association. For services to People with Parkinson's Disease. Peter Stewart Clemson. Founder and Chair, Little Theatre Company. For services to the Performing Arts and to the community in Burton-on-Trent, Staffordshire. Judith Mary Climer. Founder, Michael Climer Legacy Fund. For services to the community in Caerphilly. Isobel Jennifer Clink. For services to Golf. Joy Henrietta Mary Coalter. Lately Building and Cleaning Supervisor, Brookeborough Primary School, County Fermanagh. For services to Education. Robert Coburn. Scottish Area Vice Chair, Royal Naval Association and Poppy Appeal Convenor. For voluntary service to Veterans and to the community in Inverness-shire (to be dated 27th November 2023). Dr Shara Cohen. Chief Executive Officer, Honnao Ltd. For voluntary services to Women in STEM and to Cancer Patients and their Families.

Sources: en.wikipedia.org

Background from the literature

=== Lymphangioleiomyomatosis === In May 2015, the FDA approved sirolimus to treat lymphangioleiomyomatosis (LAM), a rare, progressive lung disease that primarily affects women of childbearing age. This made sirolimus the first drug approved to treat this disease. LAM involves lung tissue infiltration with smooth muscle-like cells with mutations of the tuberous sclerosis complex gene (TSC2). Loss of TSC2 gene function activates the mTOR signaling pathway, resulting in the release of lymphangiogenic growth factors. Sirolimus blocks this pathway. The safety and efficacy of sirolimus treatment of LAM were investigated in clinical trials that compared sirolimus treatment with a placebo group in 89 patients for 12 months. The patients were observed for 12 months after the treatment had ended. The most commonly reported side effects of sirolimus treatment of LAM were mouth and lip ulcers, diarrhea, abdominal pain, nausea, sore throat, acne, chest pain, leg swelling, upper respiratory tract infection, headache, dizziness, muscle pain and elevated cholesterol. Serious side effects including hypersensitivity and swelling (edema) have been observed in renal transplant patients. While sirolimus was considered for treatment of LAM, it received orphan drug designation status because LAM is a rare condition. The safety of LAM treatment by sirolimus in people younger than 18 years old has not been tested.

== Mental health assistance == Due to the discrimination they face, trans individuals often present significant mental health disparities. Among them, it is estimated that 32-50% of trans individuals across various countries have attempted suicide, with this high prevalence attributed to factors such as victimization, bullying, violence, social and familial rejection, as well as discrimination in different public sectors. Other than gender dysphoria, trans individuals are also affected by mental health diagnoses, such as major depression and generalized anxiety, at far greater rates than the non-trans population. Whilst gender-affirming care has a positive impact on trans individuals' mental health and may lessen several symptoms, the psychological improvements of such care are often limited by the minority stressors affecting the trans population. Due to these factors, mental health assistance through means such as psychotherapy may play an important role in addressing trans patients' mental health. Mental health assessments and treatment may be conducted prior to the initiation of gender-affirming care as a means of ensuring the patient's informed consent and complementing medical transition. Pyschotherapy as a requirement for the inititation of affirmative medical care today is discouraged by trans health care protocols, as are approaches attempting to change the patient's identity or skew self-exploration towards one particular direction.

Cross-linking of soluble hydrophilic monomers forms a 3D insoluble netted structure which can incorporate a large amount of water. The 3D polymeric network of hydrogels is highly hydrated with 90-99% water w/w; it is capable of binding many times more water molecules when assembled than in the uncross-linked state. Hydrogel dressings can absorb up to 600 times their initial amount of water, including fluid-based wound exudates. Hydrogels are effective biomaterials for wound dressings and tissue engineering because they exchange fluid, hydrating necrotic tissues. The absorption of secretions causes the hydrogel dressing to swell, expanding the cross links in the polymer chains. The expanded 3D cross-linked network can irreversibly incorporate pathogens and detritus, thereby removing them from the wound. Some hydrogel dressings have intrinsic antimicrobial properties. Hydrogel dressings formed from antimicrobial peptides (AMPs) and chitosan have inherent antimicrobial activity. The antimicrobial properties of hydrogel dressings can be enhanced by addition of metal nanoparticles, antibiotics, or other antimicrobial agents. Silver and gold nanoparticles can also be incorporated into hydrogel dressings to enhance antimicrobial activity. Some hydrogel dressings have antibiotics such as ciprofloxacin and amoxicillin incorporated into their structure which are unloaded into the wound as fluid is exchanged. Some hydrogel dressings have incorporated stimuli-responsive nitric oxide-releasing agents and other antimicrobial agents.

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 also known as?

Cardarine is commonly known as GW501516 or GW-1516. These names refer to the same synthetic compound. It is not a brand-name approved medicine.

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