Anti-doping raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-04-17 and is reviewed periodically as new material appears.
Laboratory detection of cardarine typically involves sample preparation followed by chromatographic separation and mass spectrometric identification. Urine is the most common matrix for anti-doping tests, though blood and hair have also been explored. Methods can target the parent compound or its metabolites, depending on the expected window of detection. Reference standards are required for accurate quantification. Matrix effects and dilution can influence results, so laboratories use internal standards and validation protocols. The exact detection window varies with dose, route, and individual metabolism.
A common misconception is that cardarine has been proven safe for human use. In reality, human clinical data are limited, and long-term animal studies have raised concerns about cancer. Another misconception is that it is a supplement or vitamin-like compound. It is a synthetic research chemical with no approved medical indication. Scientific discussion often focuses on its mechanism and detection rather than therapeutic use. Regulatory and anti-doping literature treats it primarily as a prohibited substance.
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.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Prohibited in sport | Listed by WADA as a PPARδ agonist. |
| Typical detection matrix | Urine | Most common sample for anti-doping analysis. |
| Common analytical method | LC-MS/MS | Liquid chromatography-tandem mass spectrometry. |
| Common synonyms | GW501516, GSK-516, endurobol | Names found in research and fitness contexts. |
| Typical detection window | Variable | Depends on dose, route, and individual metabolism. |
Stability of GW501516 depends on form, temperature, light exposure, and moisture. Solid reference material is typically stored frozen or refrigerated in a desiccator and protected from light. Solutions in organic solvents such as dimethyl sulfoxide are often kept frozen in aliquots to reduce freeze-thaw cycling. Aqueous solubility is low, so aqueous stock solutions can be difficult to prepare without cosolvents. Degradation may appear as changes in chromatographic purity or mass spectral signal. Stability studies are needed to establish shelf life for any specific preparation.
Quality assessment for cardarine samples usually combines identity, purity, and impurity testing. Nuclear magnetic resonance spectroscopy and mass spectrometry can confirm molecular structure, while high-performance liquid chromatography estimates purity. Certificates of analysis from testing laboratories may list these results, but they do not establish safety or legality. In the absence of approved manufacturing, products sold online may contain the wrong compound, variable amounts, or unlisted contaminants. Independent verification is therefore central to analytical work and to interpreting any reported biological activity.
Laboratory detection of GW501516 commonly uses liquid chromatography coupled with tandem mass spectrometry. The method can identify the parent compound or its metabolites in urine and blood after sample cleanup. Protein precipitation, solid-phase extraction, or enzymatic hydrolysis may precede analysis, depending on the matrix. Reference standards are required for accurate quantification and confirmation. Because the compound is not approved, testing often occurs in anti-doping, forensic, or research settings rather than routine clinical care. Results are reported with limits of detection and quantification.
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.
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.
Unichem Laboratories is an Indian pharmaceutical company, headquartered in Mumbai. It manufactures and markets pharmaceutical formulations across the globe, including the regulated markets of the USA and Europe.
==== Earliest research ==== Charles P. Slichter wrote that "In 1955, Redfield showed that the conventional theory of saturation did not properly account for the experimental facts of nuclear resonance in solids...[Redfield] showed that the conventional approach essentially defied the second law of thermodynamics." Redfield studied NMR with Charles Pence Slichter, assisting with early superconductivity experiments at University of Illinois, Urbana and published the Redfield Theory as a postdoc under Nicolaas Bloembergen at Harvard. At first he studied electron removal in argon, hydrogen and crypton, and the movement of electrons in photoconductors, including his doctoral thesis on the Hall effect in diamonds and salt crystals. After his breakthrough work on relaxation theory, he continued to produce papers on nuclear spin relaxation.
=== Neuromodulation === Neuromodulation is the second-oldest and third-largest department of Medtronic. Its products include neurostimulation systems and implantable drug delivery systems for chronic pain, common movement disorders, and urologic and gastrointestinal disorders. The department's revenues in 2014 amounted to $1.9 billion, or 11% of Medtronic's total revenues.
Sources: en.wikipedia.org
== Career == In 1979, Limbird joined Vanderbilt University as an Assistant Professor of Pharmacology. She led her own lab for several years, focusing on the actions of epinephrine and norepinephrine in alpha2-adrenergic receptor pathways. Limbird served as Chair of the Department of Pharmacology at the Vanderbilt School of Medicine from 1991-1998, and was the first Associate Vice Chancellor for Research of the Vanderbilt University Medical Center from 1998-2003. With Hal Moses, Limbird was instrumental in determining the 1997 strategic plan for the program. After 25 years at Vanderbilt, Limbird chose to join minority-serving institutions, in hopes of using her scientific administrative, and personal experience to help counter the impact of systemic racism. In 2005, she became Vice President for Research and Chair of the Department of Biomedical Sciences at Meharry Medical College. In 2008, Limbird became Dean of the School of Natural Sciences, Mathematics and Business Administration at Fisk University in Nashville, Tennessee.
== Xenon-124 == Xenon-124 is an isotope of xenon that undergoes double electron capture to tellurium-124 with a very long half-life of 1.1×1022 years, approximately 12 orders of magnitude longer than the age of the universe. This decay was observed in the XENON1T detector in 2019, and is the slowest one ever directly observed. (Even slower decays of other nuclei have been measured, but by detecting decay products that have accumulated over billions of years rather than observing them directly.)
Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP. Its most likely mechanism of action is activation of intracellular protein kinases in response to the binding of membrane-impermeable peptide hormones to the external cell surface. Through protein kinases activation, cGMP can relax smooth muscle. cGMP concentration in urine can be measured for kidney function and diabetes detection.
RU-24213, also known as 3-hydroxy-N-propyl-N-(phenylethyl)phenethylamine, is a dopamine receptor agonist of the phenethylamine family related to dopamine. It is a selective dopamine D2-like receptor agonist. Subsequently, however, RU-24213 was found to also act as a potent κ-opioid receptor (KOR) antagonist. It led to the development of the diphenylethylamine series of KOR ligands. RU-24213 was first described in the scientific literature in 1978.
Sources: en.wikipedia.org
Yes, WADA prohibits cardarine as a PPARδ agonist. It appears on the prohibited list and can be detected in urine or blood. Athletes using it risk sanctions.
Detection usually uses liquid chromatography-tandem mass spectrometry after sample cleanup. Laboratories look for the parent compound or metabolites. The method requires validated reference standards and controls.
Legality varies by country. In many places it is an unapproved drug and cannot be legally sold for human consumption. Purchasing from online vendors carries legal and quality risks.
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.