A practical reference on PPARδ agonist: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-23. Anything still debated is marked as such rather than presented as settled.
Cardarine is a common name for GW501516, a synthetic compound studied for its effects on lipid and glucose metabolism. It functions as an agonist at peroxisome proliferator-activated receptor delta, or PPARδ, a nuclear receptor that influences gene expression. The molecule is not a steroid, nor is it a selective androgen receptor modulator. It is also known in research and sports literature as GW-501516 and endurobol. Early laboratory work examined its metabolic activity in cell cultures and animal models.
Activation of PPARδ changes transcription of genes involved in fatty acid transport, mitochondrial function, and skeletal muscle fuel preference. In rodent studies, pharmacological PPARδ activation was associated with increased endurance and altered body composition. These findings generated interest in performance enhancement, but species differences and study designs limit direct extrapolation to humans. Small human trials were conducted in the 2000s and later discontinued. The extent to which cardarine produces similar metabolic or performance effects in people remains an open question.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic PPARδ agonist | Not a steroid or a selective androgen receptor modulator. |
| Common synonyms | Cardarine, GW501516, GW-501516, endurobol | Names vary by supplier and literature source. |
| Appearance | White to off-white powder | Consistent with many small-molecule research chemicals. |
| Solubility | Low in water; soluble in DMSO and ethanol | Often prepared in organic solvent for laboratory work. |
| Primary target | PPARδ (NR1C2) | Nuclear receptor involved in lipid and energy metabolism. |
Early clinical research explored GW501516 for lipid disorders, obesity, and diabetes. Some short-term human studies reported changes in HDL cholesterol, LDL cholesterol, and triglycerides. The development program was discontinued after rodent studies showed dose-dependent tumor formation in multiple tissues, including liver, bladder, stomach, and skin. These findings raised concerns about long-term cancer risk in humans. Because human exposure data are limited, the clinical significance of the rodent tumors remains uncertain.
Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.
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.
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.
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.
In pharmacology, relative bioavailability measures the bioavailability (estimated as the AUC) of a formulation (A) of a certain drug when compared with another formulation (B) of the same drug, usually an established standard, or through administration via a different route. When the standard consists of intravenously administered drug, this is known as absolute bioavailability (see above). F r e l = 100 ⋅ A U C A ⋅ D B A U C B ⋅ D A {\displaystyle F_{\mathrm {rel} }=100\cdot {\frac {AUC_{\mathrm {A} }\cdot D_{\mathrm {B} }}{AUC_{\mathrm {B} }\cdot D_{\mathrm {A} }}}}
GPCRs become desensitized when exposed to their ligand for a long period of time. There are two recognized forms of desensitization: 1) homologous desensitization, in which the activated GPCR is downregulated; and 2) heterologous desensitization, wherein the activated GPCR causes downregulation of a different GPCR. The key reaction of this downregulation is the phosphorylation of the intracellular (or cytoplasmic) receptor domain by protein kinases. Cyclic AMP-dependent protein kinases (protein kinase A) are activated by the signal chain coming from the G protein (that was activated by the receptor) via adenylate cyclase and cyclic AMP (cAMP). In a feedback mechanism, these activated kinases phosphorylate the receptor. The longer the receptor remains active the more kinases are activated and the more receptors are phosphorylated. In β2-adrenoceptors, this phosphorylation results in the switching of the coupling from the Gs class of G-protein to the Gi class. cAMP-dependent PKA mediated phosphorylation can cause heterologous desensitisation in receptors other than those activated.
The American Society for Mass Spectrometry (ASMS) is a professional association based in the United States that supports the scientific field of mass spectrometry. As of 2018, the society had approximately 10,000 members primarily from the US, but also from around the world. The society holds a large annual meeting, typically in late May or early June as well as other topical conferences and workshops. The society publishes the Journal of the American Society for Mass Spectrometry.
Sources: en.wikipedia.org
In the USA, anethole is generally recognized as safe (GRAS). After a hiatus due to safety concerns, anethole was reaffirmed by Flavor and Extract Manufacturers Association (FEMA) as GRAS. The concerns related to liver toxicity and possible carcinogenic activity reported in rats. Anethole is associated with a slight increase in liver cancer in rats, although the evidence is scant and generally regarded as evidence that anethole is not a carcinogen. An evaluation of anethole by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) found its notable pharmacologic properties to be reduction in motor activity, lowering of body temperature, and hypnotic, analgesic, and anticonvulsant effects. A subsequent evaluation by JECFA found some reason for concern regarding carcinogenicity, but there is currently insufficient data to support this. At this time, the JECFA summary of these evaluations is that anethole has "no safety concern at current levels of intake when used as a flavoring agent". In large quantities, anethole is slightly toxic and may act as an irritant.
In some reactions, protons and hydroxide may directly act as acid and base in term of specific acid and specific base catalysis. But more often groups in substrate and active site act as Brønsted–Lowry acid and base. This is called general acid and general base theory. The easiest way to distinguish between them is to check whether the reaction rate is determined by the concentrations of the general acid and base. If the answer is yes then the reaction is the general type. Since most enzymes have an optimum pH of 6 to 7, the amino acids in the side chain usually have a pKa of 4~10. Candidate include aspartate, glutamate, histidine, cysteine. These acids and bases can stabilise the nucleophile or electrophile formed during the catalysis by providing positive and negative charges.
The cellular response in signal transduction cascades involves alteration of the expression of effector genes or activation/inhibition of targeted proteins. Regulation of protein activity mainly involves phosphorylation/dephosphorylation events, leading to its activation or inhibition. It is the case for the vast majority of responses as a consequence of the binding of the primary messengers to membrane receptors. This response is quick, as it involves regulation of molecules that are already present in the cell. On the other hand, the induction or repression of the expression of genes requires the binding of transcriptional factors to the regulatory sequences of these genes. The transcriptional factors are activated by the primary messengers, in most cases, due to their function as nuclear receptors for these messengers. The secondary messengers like DAG or Ca2+ could also induce or repress gene expression, via transcriptional factors. This response is slower than the first because it involves more steps, like transcription of genes and then the effect of newly formed proteins in a specific target. The target could be a protein or another gene.
At the regulatory site, the binding of a ligand may elicit amplified or inhibited protein function. The binding of a ligand to an allosteric site of a multimeric enzyme often induces positive cooperativity, that is the binding of one substrate induces a favorable conformation change and increases the enzyme's likelihood to bind to a second substrate. Regulatory site ligands can involve homotropic and heterotropic ligands, in which single or multiple types of molecule affects enzyme activity respectively. Enzymes that are highly regulated are often essential in metabolic pathways. For example, phosphofructokinase (PFK), which phosphorylates fructose in glycolysis, is largely regulated by ATP. Its regulation in glycolysis is imperative because it is the committing and rate limiting step of the pathway. PFK also controls the amount of glucose designated to form ATP through the catabolic pathway. Therefore, at sufficient levels of ATP, PFK is allosterically inhibited by ATP. This regulation efficiently conserves glucose reserves, which may be needed for other pathways. Citrate, an intermediate of the citric acid cycle, also works as an allosteric regulator of PFK.
Sources: en.wikipedia.org
Originally, seven such proteins were discovered. Of these, six (BMP2 through BMP7) belong to the Transforming growth factor beta superfamily of proteins. BMP1 is a metalloprotease. Since then, thirteen more BMPs, all of which are in the TGF-beta family, have been discovered, bringing the total to twenty. The current nomenclature only recognizes 13, as many others are put under the growth differentiation factor naming instead.
The Analytical Information Markup Language (AnIML) is an open ASTM XML standard for storing and sharing analytical chemistry and biological data. A main reason of using AnIML is that FAIR data (Findable, Accessible, Interoperable and Reusable) standards are automatically implemented. As AnIML's structure is human-readable, Accessibility is given. Interoperability, Reusability and Findability are secured by the AnIML Core and AnIML Technique Definitions. AnIML has been continuously worked on starting from 2003 up to 2020. The last AnIML Core Version update happened in 2010. So far, no standardisation document nor public example files have been published. The standard exists only in pre-release form. AnIML is a XML standard which consists of two logical layers:
While many of the claims are based on scientifically based physiological or biochemical processes, their use in bodybuilding parlance is often heavily colored by bodybuilding lore and industry marketing and, as such, may deviate considerably from traditional scientific usages of the terms. In addition, ingredients listed have been found at times to be different from the contents. In 2015, Consumer Reports reported unsafe levels of arsenic, cadmium, lead, and mercury in several of the protein powders that were tested. In the United States, the manufacturers of dietary supplements do not need to provide the Food and Drug Administration with evidence of product safety prior to marketing. As a result, the incidence of products adulterated with illegal ingredients has continued to rise. In 2013, one-third of the supplements linked to liver damage in one study were adulterated with unlisted steroids. More recently, the prevalence of designer steroids with unknown safety and pharmacological effects has increased. In 2015, a CBC investigative report found that protein spiking (i.e., the addition of amino-acid filler to manipulate analysis) was not uncommon; however, many of the companies involved challenged these claims.
Although it is a relatively immature area of research, it appears that heterotrimeric G-proteins may also take part in non-GPCR signaling. There is evidence for roles as signal transducers in nearly all other types of receptor-mediated signaling, including integrins, receptor tyrosine kinases (RTKs), cytokine receptors (JAK/STATs), as well as modulation of various other "accessory" proteins such as GEFs, guanine-nucleotide dissociation inhibitors (GDIs) and protein phosphatases. There may even be specific proteins of these classes whose primary function is as part of GPCR-independent pathways, termed activators of G-protein signalling (AGS). Both the ubiquity of these interactions and the importance of Gα vs. Gβγ subunits to these processes are still unclear. There are two principal signal transduction pathways involving the G protein-linked receptors: the cAMP signal pathway and the phosphatidylinositol signal pathway.
Camurus is a company focused on the development of lipid lyotropic liquid crystal structures for pharmaceutical drug delivery applications. These structures are well-defined three-dimensional formations consisting of lipophilic and hydrophilic domains that can be either interconnected or isolated depending on the environmentally induced phase conditions. The unique crystalline structures offer a unique way of encapsulating and transporting Active pharmaceutical ingredients, such as small molecules, peptides and proteins through the body. The structures also allow for the use of controlled release and prevention of degradation of fragile short half live molecules, a serious issue for amino-acid based drugs.
Sources: en.wikipedia.org
Cardarine is a common name for GW501516, a synthetic PPARδ agonist. It is not a steroid or a selective androgen receptor modulator. It was developed and studied as a research compound for metabolic pathways.
It binds to and activates PPARδ, a nuclear receptor that regulates genes related to fatty acid oxidation and energy use. This activation alters transcription in tissues such as skeletal muscle and liver. The full range of downstream effects in humans is not fully established.
No, cardarine is not known to occur naturally in plants, animals, or humans. It is a synthetic molecule produced for laboratory research. Products labeled as cardarine should therefore be treated as manufactured chemicals with variable purity.
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.