Reference standard is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-05-02. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Cardarine has no approved therapeutic indication and is not marketed as a medicine. The World Anti-Doping Agency lists GW501516 as a prohibited substance at all times, covering both in-competition and out-of-competition periods. National laws vary: some countries treat it as an unapproved drug subject to import controls, while others have specific restrictions on sale for human consumption. It is often sold as a research chemical, a label that does not imply safety or legality. Enforcement actions have targeted online vendors and shipments.
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.
Published literature on cardarine includes in vitro assays, rodent experiments, and a small number of human studies. Reports describe effects on exercise capacity and lipid metabolism in animals, while human evidence is sparse. Many online descriptions present the compound as a proven endurance aid, a claim not supported by regulatory approval or large clinical trials. Analytical studies focus on identifying the parent compound and its metabolites in biological samples. Important uncertainties include species differences, dose-response relationships, and the relevance of rodent tumor findings to humans.
Cardarine is the common name for GW501516, a synthetic compound studied as a peroxisome proliferator-activated receptor delta agonist. Researchers developed it to explore treatments for lipid disorders and metabolic conditions. It is not an approved medicine in any country. Early clinical work examined changes in HDL cholesterol and triglycerides, but development was discontinued after animal studies raised concerns about cancer. The compound remains available as a research chemical and appears in discussions of performance enhancement.
At the molecular level, GW501516 binds and activates PPARδ, a nuclear receptor that regulates transcription. Activation shifts expression of genes involved in fatty acid oxidation, energy expenditure, and lipid transport in skeletal muscle and liver. Animal studies report increased endurance and altered lipid profiles after exposure. Human data are limited to small trials and do not establish long-term safety or efficacy. PPARδ also has roles in cell proliferation, so the relationship between activation and cancer risk remains an open question.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Prohibited in sport; not approved as medicine | Listed by WADA at all times. |
| Common synonyms | GW501516, GW-501516, endurobol | Cardarine is a colloquial name. |
| Typical analytical method | LC-MS/MS | Detects parent compound and metabolites. |
| Common test matrix | Urine | Blood and dried blood spots also possible. |
| Legal classification | Varies by country | Often treated as unapproved drug or research chemical. |
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.
GW501516 acts as a ligand for PPAR delta, a nuclear receptor that regulates transcription of genes involved in fatty acid oxidation and energy use. Activation of this receptor in skeletal muscle shifts metabolism toward fat burning in animal models. The compound does not burn fat directly; it changes gene expression over hours to days. Researchers study it to understand metabolic flexibility and exercise adaptation. Effects observed in rodents are not automatically expected in humans.
Cardarine is not approved for human therapeutic use in any major jurisdiction. It appears on the World Anti-Doping Agency Prohibited List as a PPARδ agonist within the hormone and metabolic modulators category. Sports organizations test for it because it has been detected in athlete samples and seized products. Regulatory actions against marketed research chemical versions have occurred in several countries, though enforcement varies. Availability through unregulated channels complicates oversight.
Analytical laboratories typically identify cardarine and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is a common matrix in anti-doping testing, while blood and tissue may be used in research settings. Detection windows depend on the assay, the sample matrix, and the compound's metabolism. Because cardarine is extensively metabolized, laboratories often target specific metabolites to improve sensitivity and confirmation. Reference standards are required for reliable quantification. Method validation includes checks for selectivity, linearity, and carryover.
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.
The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.
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 explicitly prohibited by the World Anti-Doping Agency under the class of PPARδ agonists. Its presence in urine or blood samples can be detected using mass spectrometry-based methods, often liquid chromatography-tandem mass spectrometry. Athletes who test positive may face sanctions, including bans from competition. The compound is also regulated as a prescription-only or unapproved drug in many countries. Enforcement varies by jurisdiction, and some regions treat it as a controlled substance. Online sales may occur despite these restrictions, creating quality and legal risks.
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.
Serotonylation has been reported in various cell types and tissues, including both serotonergic and dopaminergic neurons, enterochromaffin cells, cancer-associated fibroblasts, pancreatic 𝛽-cells, CD8+ T cells, pulmonary endothelial cells, platelets, neutrophils, mammary epithelial cells, vascular smooth muscle, and cells of the intestines. Serotonylation is known to influence both tumorigenesis and cancer metastasis, and has been implicated in several types of cancer, including colorectal cancer, neuroendocrine prostate cancer, pancreatic cancer, hepatocellular carcinoma, and ependymomas (brain cancer).
Paleofeces, also known as coprolites (though that name is more commonly used in reference to animal feces), are ancient human feces, often found as part of archaeological excavations or surveys. Intact feces of ancient people may be found in caves in arid climates and in other locations with suitable preservation conditions. These are studied to determine the diet and health of the people who produced them through the analysis of seeds, small bones, and parasite eggs found inside. They also may be analyzed chemically for more in-depth information on the individual who excreted them, using lipid analysis and DNA analysis. The success rate of usable DNA extraction is relatively high in paleofeces, making it more reliable than skeletal DNA retrieval.
== Research == Some related pyrrylphenylethanones had analgesic activity comparable to morphine. Some pyrrole analogues were reported to have analgesic effects comparable to lefetamine and being devoid of neurotoxic properties.
==== United States ==== DOBU is not an explicitly controlled substance in the United States. However, it could be considered a controlled substance under the Federal Analogue Act if intended for human consumption.
House of Representatives votes 222–208 to censure Rep. Paul Gosar (R–AZ) after he posted a photo-shopped anime clip of him killing Rep. Alexandria Ocasio-Cortez (D–NY) and threatening President Biden, making him the first lawmaker to be censured since Charlie Rangel in 2010. November 19 Vice President Harris serves as acting president from 10:10 am to 11:35 am EST, while President Biden undergoes a colonoscopy under anesthesia. The U.S. House of Representatives votes 220–213 to pass the Build Back Better Act, a US$1.75 trillion social and climate spending package. State of Wisconsin v Kyle Rittenhouse: Mr. Rittenhouse is found not guilty on five charges of attempted murder, after three weeks of debate, and three days of jury deliberation. November 21 – Waukesha Christmas parade attack: An SUV is driven through the annual Christmas parade in Waukesha, Wisconsin, killing six people and injuring 62 others. The alleged driver of the vehicle, 39-year-old Darrell E. Brooks, is arrested and charged with five counts of murder. November 23 – The Biden administration announces a release of 50 million oil barrels from the Strategic Petroleum Reserve to bring down inflation in conjunction with other countries' efforts, the largest release in history. An investigation into oil companies' practices is also announced. November 24 NASA launches the Double Asteroid Redirection Test (DART), the first attempt to deflect an asteroid for the purpose of learning how to protect Earth. All three defendants are found guilty of the murder of Ahmaud Arbery.
Sources: en.wikipedia.org
Because the process takes advantage of the nonlinearity of the isotherms, a larger column feed can be separated on a given column with the purified components recovered at significantly higher concentration.
== Structure == Lysine carboxypeptidase has a molecular weight of between 270 and 330 kDa (kilodaltons). It is a tetrameric glycoprotein. It is composed of two 83 kDa subunits and two active subunits between 55 kDa and 48 kDa and these are held together by non-covalent interactions. The 83 kDa subunits are regulatory and do not directly contribute to catalytic activity; they are also heavily glycosylated. These function to stabilize the active subunits and keep them in circulation. Catalytic functioning is retained when the 83 kDa subunits are eliminated from the active subunits, but they are still necessary for their support roles. The active subunits are small and relatively unstable at body temperature and blood pH, so they would not last long in the plasma without the regulatory subunits attached. The 55 kDa-48 kDa portions are both catalytically active. The primary structure of the 83 kDa subunit can be split into three main domains. The first domain is located at the N-terminus and consists of 52 amino acids with the first 27 being cysteine-rich. The second domain refers to the next 312 amino acids and it consists of 13 leucine-rich repeat (LRR) sections, each made up of 24 residues. The final C-terminal domain refers to the last 145 residues where amino acids 400-425 hold a cysteine-rich section. The secondary/tertiary structure of the subunit has not yet been experimentally determined, but it has been hypothesized based upon how other LRR proteins fold.
The findings of the study were overall regarded as not supporting the hypothesis that (R)-MDMA would produce equivalent therapeutic effects as (S)-MDMA or MDMA whilst reducing safety concerns. However, more clinical studies were called for to assess the revised estimated equivalent doses of MDMA, (R)-MDMA, and (S)-MDMA.
It is likely that this data was used to develop the initial protocols for state-sanctioned lethal injection, according to which one gram of thiopental was used to induce the coma. Most states use 5 grams to be absolutely certain the dosage is effective. Pentobarbital was introduced at the end of 2010 due to a shortage of sodium thiopental, and has since become the primary sedative in lethal injections in the United States. Barbiturates are the same class of drug used in medically assisted suicide. In euthanasia protocols, the typical dose of thiopental is 1.5 grams; the Dutch Euthanasia protocol indicates 1-1.5 grams or 2 grams in case of high barbiturate tolerance. The dose used for capital punishment is therefore about 3 times more than the dose used in euthanasia.
Sources: en.wikipedia.org
=== Nonlinear curve fitting === Nonlinear curve-fitting programs, such as Equilibrium Binding Data Analysis (EBDA) and LIGAND, are used to calculate estimates of binding parameters from saturation and competition-binding experiments. EBDA performs the initial analysis, which converts measured radioactivity into molar concentrations and creates Hill slopes and Scatchard transformations from the data. The analysis made by EBDA can then be used by LIGAND to estimate a specified model for the binding.
== Etymology == The word "kitten" derives from the Middle English word kitoun, which in turn came from the Old French chitoun or cheton. Juvenile big cats are called "cubs" rather than kittens. For the young of smaller wild felids, such as ocelots, caracals, and lynxes, either term may be used, though "kitten" is more common.
Though it is owned by the New York City Department of Parks and Recreation, Bryant Park is managed by the private not-for-profit organization Bryant Park Corporation, which was founded in 1980 and led the restoration of Bryant Park. The park is cited as a model for the success of public-private partnerships. The park is both a National Register of Historic Places listing and a New York City designated landmark.
Sources: en.wikipedia.org
Legal status varies by country. It is not approved as a medicine, and it is prohibited in sport. Some jurisdictions restrict import, sale, or possession.
Laboratories use liquid chromatography-tandem mass spectrometry to detect GW501516 and its metabolites. Urine is commonly tested, and testing can occur in and out of competition.
No, cardarine is not a SARM. It is a PPARδ agonist, which acts on a different receptor. The two classes are often confused in online discussions.
Cardarine is a common name for the investigational compound GW501516. It acts as a PPARδ agonist and is not approved for human use. It is prohibited in sport.