Everything below concerns PPAR delta. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| IUPAC name | {4-[({4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-5-yl}methyl)sulfanyl]phenoxy}acetic acid | Systematic name for GW501516 |
| CAS Registry Number | 317318-70-0 | Unique identifier for the parent compound |
| Molecular formula | C21H18F3NO3S2 | Includes carbon, hydrogen, fluorine, nitrogen, oxygen, and sulfur |
| Molecular weight | 453.5 g/mol | Approximate value for the neutral form |
| Appearance | White to off-white powder | Typical description for purified laboratory material |
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.
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.
GW501516 acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in transcription of genes related to lipid handling and energy use. Activation of PPARδ can shift skeletal muscle toward greater fatty acid oxidation in animal models, which is one reason it drew interest for metabolic disease and exercise research. The exact downstream effects depend on tissue, species, dose, and duration. Human data are sparse, so many proposed benefits remain hypotheses rather than established clinical outcomes.
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.
=== Leukocyte adhesion deficiency and the "multistep paradigm" === Working with physicians seeing patients with recurring, life-threatening bacterial infections, Springer found their leukocytes lacked LFA-1 (αLβ2), Mac-1 (αMβ2), and αXβ2. Anderson and Springer named the disease leukocyte adhesion deficiency (LAD) in a review article, and it was shown to be caused by mutations in the β2 subunit common to the leukocyte integrins. Patients have abnormally high levels of neutrophils in their circulation, which cannot emigrate out of the bloodstream to fight infection. This demonstrated that β2 integrins were important in leukocyte interactions with vascular endothelial cells and stimulated Springer to set up work in the lab on endothelial cells and flow chambers. In related work on LFA-1 ligands, ICAM-1 and ICAM-2 were shown to be inducible and constitutively expressed, respectively, on endothelium. It had long been known from intravital microscopy that leukocyte emigration involved leukocyte rolling on endothelium followed by firm adhesion and subsequent transendothelial migration. Using white blood cells infused in flow chambers and purified adhesion molecules on the chamber walls under physiological shear rates found in vivo, Springer and postdoctoral fellow Mike Lawrence reconstituted three sequential interactions required for leukocyte emigration. Flow chamber walls were coated with P-selectin, ICAM-1, or both. Infused neutrophils were found to readily attach and then roll on P-selectin, but could not attach to ICAM-1 in flow.
During the development of Half-Life 2, Newell spent months developing Steam, a digital distribution service for games. By 2011, Steam controlled between 50% and 70% of the market for downloaded PC games and generated most of Valve's revenue. At a technology conference in Seattle that year, Newell argued that software piracy was best addressed by offering a superior option rather than pursuing anti-piracy technology. He cited Steam's success in Russia, where piracy is rife, as an example. Following the difficult development of Half-Life 2, Newell said he became "obsessed" with improving Valve's work-life balance.In 2007, Newell expressed his displeasure over developing for game consoles, saying that developing processes for Sony's PlayStation 3 was a "waste of everybody's time". On stage at Sony's keynote at E3 2010, he acknowledged his criticism but discussed the open nature of the PlayStation 3 and announced a port of Portal 2, remarking that with Steamworks support it would be the best version for any console. Newell also criticized the Xbox Live service, referring to it as a "train wreck", and Windows 8, calling it a threat to the open nature of PC gaming. At the 2013 LinuxCon, Newell said the Linux operating system and open source development were "the future of gaming". He accused the proprietary systems of companies such as Microsoft and Apple of stifling innovation through slow certification processes.
=== Designed nucleic acid systems === Scientists can encode digital information onto a single strand of synthetic DNA. In 2012, George M. Church encoded one of his books about synthetic biology in DNA. The 5.3 Mb of data was more than 1000 times greater than the previous largest amount of information to be stored in synthesized DNA. A similar project encoded the complete sonnets of William Shakespeare in DNA. More generally, algorithms such as NUPACK, ViennaRNA, Ribosome Binding Site Calculator, Cello, and Non-Repetitive Parts Calculator enables the design of new genetic systems. Many technologies have been developed for incorporating unnatural nucleotides and amino acids into nucleic acids and proteins, both in vitro and in vivo. For example, in May 2014, researchers announced that they had successfully introduced two new artificial nucleotides into bacterial DNA. By including individual artificial nucleotides in the culture media, they were able to exchange the bacteria 24 times; they did not generate mRNA or proteins able to use the artificial nucleotides.
This was after increasing demands to establish a UN approved body by more than a hundred Syrian civil society groups and human rights organizations like the Amnesty International, Human Rights Watch and International Committee of the Red Cross. The objective of the new body is to ensure better co-ordination to collect information of disappeared individuals. The Assad regime denounced the vote as "flagrant interference" in Syria's domestic issues.
AST exists in two isoenzymes namely mitochondrial form and cytoplasmic form. It is found in highest concentration in the liver, followed by heart, muscle, kidney, brain, pancreas, and lungs. This wide range of AST containing organs makes it a relatively less specific indicator of liver damage compared to ALT. An increase of mitochondrial AST in bloods is highly suggestive of tissue necrosis in myocardial infarction and chronic liver disease. More than 80% of the liver AST activity are contributed by mitochondrial form of the isoenzymes, while the circulating AST in blood are contributed by cytoplasmic form of AST. AST is especially markedly raised in those with liver cirrhosis. AST can be released from a variety of other tissues and if the elevation is less than two times the normal AST, no further workup needs to be performed if a patient is proceeding to surgery. In certain pregnancy related conditions such as hyperemesis gravidarum, AST can reach as high as 73 IU/L, 66 IU/L in pre-eclampsia, and 81 IU/L in HELLP syndrome.
Sources: en.wikipedia.org
=== Anesthesia === Esketamine is used for similar indications as ketamine. Such uses include induction of anesthesia in high-risk patients such as those with circulatory shock, severe bronchospasm, or as a supplement to regional anesthesia with incomplete nerve blocks. Esketamine binds more strongly to NMDA receptors than racemic ketamine, making it roughly twice as potent with faster recovery and fewer cognitive side effects; its pain relief benefits are somewhat inconsistent.
is the fraction of receptor bound by the ligand. This expression is one way to consider the effect of a drug, in which the response is related to the fraction of bound receptors (see: Hill equation). The fraction of bound receptors is known as occupancy. The relationship between occupancy and pharmacological response is usually non-linear. This explains the so-called receptor reserve phenomenon i.e. the concentration producing 50% occupancy is typically higher than the concentration producing 50% of maximum response. More precisely, receptor reserve refers to a phenomenon whereby stimulation of only a fraction of the whole receptor population apparently elicits the maximal effect achievable in a particular tissue. The simplest interpretation of receptor reserve is that it is a model that states there are excess receptors on the cell surface than what is necessary for full effect. Taking a more sophisticated approach, receptor reserve is an integrative measure of the response-inducing capacity of an agonist (in some receptor models it is termed intrinsic efficacy or intrinsic activity) and of the signal amplification capacity of the corresponding receptor (and its downstream signaling pathways). Thus, the existence (and magnitude) of receptor reserve depends on the agonist (efficacy), tissue (signal amplification ability) and measured effect (pathways activated to cause signal amplification). As receptor reserve is very sensitive to agonist's intrinsic efficacy, it is usually defined only for full (high-efficacy) agonists.
The structure of hemoglobins varies across species. Hemoglobin occurs in all kingdoms of organisms, but not in all organisms. Primitive species such as bacteria, protozoa, algae, and plants often have single-globin hemoglobins. Many nematode worms, molluscs, and crustaceans contain very large multisubunit molecules, much larger than those in vertebrates. In particular, chimeric hemoglobins found in fungi and giant annelids may contain both globin and other types of proteins. One of the most striking occurrences and uses of hemoglobin in organisms is in the giant tube worm (Riftia pachyptila, also called Vestimentifera), which can reach 2.4 meters length and populates ocean volcanic vents. Instead of a digestive tract, these worms contain a population of bacteria constituting half the organism's weight. The bacteria oxidize H2S from the vent with O2 from the water to produce energy to make food from H2O and CO2. The worms' upper end is a deep-red fan-like structure ("plume"), which extends into the water and absorbs H2S and O2 for the bacteria, and CO2 for use as synthetic raw material similar to photosynthetic plants. The structures are bright red due to their content of several extraordinarily complex hemoglobins that have up to 144 globin chains, each including associated heme structures. These hemoglobins are remarkable for being able to carry oxygen in the presence of sulfide, and even to carry sulfide, without being completely "poisoned" or inhibited by it as hemoglobins in most other species are.
On July 23, 2013, Taco Bell announced they were discontinuing the sale of kids' meals and accompanying toys at all of their U.S.–based restaurants by January 2014. Some outlets ceased their sale as early as July 2013. On August 6, 2013, the chain announced it was expanding its test market of "Waffle Tacos" to ≈100 restaurants in Fresno, California, Omaha, Nebraska, and Chattanooga, Tennessee, beginning on August 8 of that year. The Waffle Taco included scrambled eggs, sausage, and a side of syrup. It was the top–selling item during breakfast hours at the five Southern California restaurants where they had been test–released earlier in 2013. The breakfast menu started on March 27, 2014. Other items include: the A.M. Crunchwrap, Cinnabon Delights, Breakfast Burrito, A.M. Grilled Sausage Flatbread Melt, Hash Browns, Coffee and Orange Juice. The ad–campaign, which began March 27, used twenty-five men who were named Ronald McDonald, a reference to the famous clown mascot of McDonald's. Another commercial advertisement for the Waffle Taco features the narrator singing, "I've been eating Egg McMuffins since 1984. But when I saw Taco Bell made a Waffle Taco, I figured I would get with the times" set to the tune of "Old MacDonald Had a Farm"— another shot at McDonald's. On April 28, 2014, Taco Bell ridiculed McDonald's for its "out–dated muffins", in a breakfast campaign devised by Taylor. The advertisement stated the claim that the McMuffin belonged in 1984. In October 2014, Taco Bell launched the Pink Strawberry Starburst Freeze beverage for a limited time.
Sources: en.wikipedia.org
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.
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.
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.
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.