A practical reference on nuclear receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-17. Anything still debated is marked as such rather than presented as settled.
Cardarine is a common name for GW501516, an investigational compound developed in the 1990s for metabolic conditions. It acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in lipid and energy metabolism. The compound is frequently mislabeled as a selective androgen receptor modulator, or SARM, but its molecular target is different. GW501516 reached early clinical testing before development was discontinued. It has no approved therapeutic use in any country. The name cardarine is not a formal international nonproprietary name.
Regulatory treatment varies, but cardarine is not approved as a medicine. Sports authorities list GW501516 as a prohibited substance, and it is banned at all times under the World Anti-Doping Agency code. Many countries restrict sales for human consumption, while online vendors market it as a research chemical. Such products may lack purity data, and their actual contents can differ from the label. Purchasing or possessing cardarine may carry legal consequences depending on jurisdiction. The compound is not a dietary supplement ingredient in regulated markets.
Clinical development stopped after rodent studies showed tumors at multiple sites. Whether those findings predict human cancer risk remains an open question, but they led sponsors to discontinue programs. Human safety data are limited to small, short-term studies that were not designed to assess cancer risk. Reported effects in those studies included changes in blood lipids, but the evidence is insufficient for medical use. Long-term consequences of nonmedical use are not well characterized. Questions about dose, duration, and individual susceptibility remain unresolved.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | GW501516; GW-1516; endurobol | GW501516 is the research code |
| Drug class | PPARδ agonist | Not a selective androgen receptor modulator |
| Molecular formula | C21H18F3NO3S2 | Established chemical formula |
| Molar mass | 453.5 g/mol | Calculated from the formula |
| Regulatory status | Prohibited in sport; not approved as medicine | Status varies by country |
Laboratory studies have examined GW501516 in cell cultures and rodents for conditions such as dyslipidemia, insulin resistance, and obesity. Some trials in humans were initiated, but development was discontinued after preclinical findings raised concerns about cancer in certain models. Those findings do not prove that the compound causes cancer in people, but they contributed to regulatory caution. Later reviews often describe the evidence as preliminary and insufficient for assessing long-term safety.
In the fitness and bodybuilding literature, cardarine is frequently discussed as an endurance agent or fat-loss compound, although such claims are not supported by robust clinical evidence. Online descriptions often mix animal data, user anecdotes, and marketing language. Researchers who study PPARδ agonists distinguish between receptor activation in controlled experiments and unsupervised use of unverified products. The latter introduces unknown purity, dose, and interactions, making reported experiences difficult to interpret scientifically.
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.
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.
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.
A persistent misconception is that cardarine is a fat-burning drug or a safe alternative to anabolic steroids. No approved therapeutic product exists, and human safety data are limited. The tumor findings in rodents remain a central concern in scientific reviews. Products sold online may contain inaccurate labels, impurities, or different compounds entirely, which complicates any assessment of effects. Independent testing of such products has reported frequent mislabeling. For these reasons, discussions in the literature emphasize risks and unknowns rather than benefits.
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.
=== Polonium murder === On November 23, 2006, Alexander Alexanderovich Litvinenko (1962-2006) was murdered under unexplained circumstances as a result of radiation sickness caused by polonium. This was also briefly suspected in the case of Yasser Arafat (1929-2004), who died in 2004.
Only one Ambrosiella (A. cleistominuta from the xyleborine ambrosia beetle Anisandrus maiche) has ever been reported to produce sexual structures, and the rest (including A. roeperi) have been assumed to undergo exclusively clonal reproduction. All Ambrosiella produce translucent, flask-shaped conidiogenous cells (phialides) borne on non-fertile sporodochia (minute, dense cushions of nonreproductive hyphae holding up the fertile tissue). Conidia may arise from these phialides as chains – i.e., new spores are successively pushed out, with the newest growth closest to the original conidiogenous cell – or singly, as an aleurioconidium that ruptures the membrane of the mother cell and then remains a unique, differentiated terminal unit without any subsequent neighbors produced from the phialide. A. roeperi operates only through the latter mechanism, which is distinct from what is reported in A. beaveri, A. trypodendri, and A. hartigii (suggested to use the former, chain-like method).
Paul Halverson, director and state health officer for the Arkansas Department of Health, approved an emergency rule to ban the sale and distribution of phenazepam shortly after the Louisiana ban. Alabama made phenazepam a Schedule I substance on March 18, 2014.
Sources: en.wikipedia.org
== Cause == CJD is a type of transmissible spongiform encephalopathy (TSE), which is caused by prions. Prions are misfolded proteins that occur in the neurons of the central nervous system (CNS). The CJD prion is dangerous because it promotes refolding of cellular prion proteins into the diseased state. The number of misfolded protein molecules will increase exponentially, and the process leads to a large quantity of insoluble proteins in affected cells. This mass of misfolded proteins disrupts neuronal cell function and causes cell death. Mutations in the gene for the prion protein can cause a misfolding of the dominantly alpha helical regions into beta pleated sheets. This change in conformation disables the protein's ability to undergo digestion. Once the prion is transmitted, the defective proteins invade the brain and induce other prion protein molecules to misfold in a self-sustaining feedback loop. These neurodegenerative diseases are commonly called prion diseases. PrPC, the normal fibril cellular proteins responsible for a wide range of CNS functions, are misfolded by what current research suggests are small, highly neurotoxic oligomeric aggregates, known as PrPSc, which interact with cell surfaces to disrupt neuronal function. The binding of prion oligomers to normal prion protein on neurons may trigger toxic signals similar to how oligomeric β-amyloid causes synaptic damage in Alzheimer's disease.
== Doubly substituted isotopologues == Measurement of the abundance of clumped isotopes (doubly substituted isotopologues) of gases has been used in the field of stable isotope geochemistry to trace equilibrium and kinetic processes in the environment inaccessible by analysis of singly substituted isotopologues alone. Currently measured doubly substituted isotopologues include:
== Contraindications == Contraindications of cyproheptadine include newborns and premature infants, nursing mothers, hypersensitivity to cyproheptadine and its ingredients, monoamine oxidase inhibitors (MAOIs), angle-closure glaucoma, stenosing peptic ulcer symptomatic prostatic hypertrophy, bladder neck obstruction, pyloroduodenal obstruction, and elderly, debilitated patients.
Osedax is a genus of siboglinid polychaetes, commonly called snot worms, bone-eating worms, or zombie worms. Osedax is Latin for 'bone devourer', derived from the worms' unique ecological niche of bone-boring. Osedax settle on a bone, then secrete an acid through specialized root tissues to dissolve the bone's external layers in order to access the lipids within. Osedax act as ecosystem engineers, enhancing the biodiversity of bones they inhabit by increasing their structural complexity, allowing microfauna to inhabit otherwise inaccessible regions of the internal bone. Scientists from the Monterey Bay Aquarium Research Institute using the submarine ROV Tiburon first discovered the genus in Monterey Bay, California, in February 2002. The worms were found living on the bones of a decaying gray whale in the Monterey Canyon, at a depth of 2,893 m (9,491 ft).
Sources: en.wikipedia.org
No. Cardarine is GW501516, a PPARδ agonist, while SARMs act on androgen receptors. The two classes are often grouped in informal discussions despite different mechanisms.
No. It has no approved medical indication in any country. Regulatory agencies have not cleared it for treatment or prevention of any condition.
Early clinical work stopped after rodent carcinogenicity findings. Those animal results raised concerns about long-term human risk, although direct human evidence is lacking. The human relevance of the tumors remains an open scientific question.
Cardarine targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not bind the androgen receptor in the way SARMs do.