Cardarine, also known as GW501516, it is not a peptide. It is a synthetic, small molecule organic compound that activates the receptor activated by the peroxisome proliferator-activated receptor delta (PPARδ, also known as PPARβ/δ). It is a nuclear receptor involved in the regulation of genes related to metabolism. Cardarine is also not a selective androgen receptor modulator (SARM), although it often appears alongside peptides and SARM in online catalogs. The chemical classification should be based on the structure and mechanism of action of the substance, not on the category chosen by the seller. 1
GW501516 has been studied in humans for short-term changes in lipid metabolism, and in animals its effects on physiological processes related to exercise have been analyzed. However, the history of research also includes serious findings regarding carcinogenicity in rodents. The available evidence does not support safe, approved therapeutic use or use to improve physical performance. Biological activity is not equivalent to proven clinical benefit or acceptable long-term risk. 2
The article discusses the names and chemical classification of Cardarine, the most important results of human and animal studies, the proposed mechanisms of action, and the limitations of the evidence regarding safety and physical performance.
What is Cardarine? Names, synonyms, and chemical identity
The name Cardarine usually refers to the compound GW501516. In scientific publications and anti-doping documents, the designations GW-501516, GW 501516, GW1516 and the name Endurobol are also used.
The PubChem database identifies this substance with the CID number 9803963, while the US FDA substance identification system assigns it the UNII number 7I2HA1NU22. These identifiers make it easier to find documents that use different variant names. 1 3
The presence of a substance identifier does not mean that it has been approved as a medicine.
It also does not confirm the authenticity of the product offered online.
The powder, capsule, or multi-ingredient preparation sold as Cardarine may differ in composition and quality from the substance used in the published study.
It is equally important to distinguish GW501516 from other PPARδ agonists.
Agents that act on the same receptor can be useful for scientific comparisons, but this does not mean that they have identical chemical structure, pharmacokinetics, toxicity, or clinical activity.
When interpreting the results, the most important thing is to determine the exact identity of the substance under study, followed by its formulation and experimental conditions.
Marketing labels and general product categories should not replace this information.
Is Cardarine a peptide, a protein, an SARM, or a small molecule organic compound?
Cardarine is a nonpeptide compound of small molecule structure.
It does not consist of residual amino acids linked by peptide bonds, therefore there is no amino acid sequence that could be presented.
Its recognized pharmacological activity is an agonist of the PPARβ/δ receptor, belonging to the family of nuclear receptors. 1
This mechanism differs from the action of SARM drugs, which act on the androgen receptor.
Describing Cardarine as an SARM simply because it is in the category of products related to bodybuilding is therefore incorrect both chemically and pharmacologically.
The term „metabolic modulator” is, however, a separate category used in anti-doping regulations.
The World Anti-Doping Agency (WADA) list of prohibited substances for 2026 lists GW1516/GW501516 in category S4.4.1, which includes PPARδ agonists. The substance is prohibited both during and outside of competitions.
However, the sports ban should not be equated with the global status of drug registration or with the criminal laws in effect in individual countries. 4
| Term | Correct interpretation | What it does not mean |
|---|---|---|
| Covalent bond | Non-peptide organic compound | Short peptide or protein |
| PPARδ agonist | It activates a nuclear receptor associated with metabolism | Modulation of the androgen receptor |
| Metabolic modulator | Anti-doping classification | Status of an approved medicinal product |
| GW501516 / GW1516 | Names related to Cardarine | Two separate medications |
| Experimental substance | The association studied under scientific conditions | Confirmed safety of use in humans |
These distinctions allow for situations where the trade name or marketing category conveys the true identity of the substance and its safety history.
Molecular structure and chemical composition of Cardarine
GW501516 has a C₂₁H₁₈F₃NO₃S₂ molecular formula and a molecular weight of approximately 453.5 g/mol.
Its structure includes aromatic and thiazole ring-related elements, as well as a carboxylic acid group.
This is a characteristic structure of a synthetic organic compound, not an amino acid polymer. 1
The entry in the FDA’s substance identification system assigns the same summary pattern to GW-501516.
This data may support chemical identification, but it does not constitute a license to market the drug or a certificate of quality for a specific product. 3
The overall pattern alone is not sufficient to confirm the authenticity of the sample.
Different compounds with different structures can have identical elemental composition.
Therefore, confirmation of identity requires appropriate structural and analytical evidence.
Purity and the designated content of the substance are further separate parameters.
The difference between the active substance and the finished formulation is also important.
Short-term studies in humans used specific experimental preparations.
They did not include all the powders and capsules sold later under the name Cardarine.
Even proper identification of the substance does not eliminate the toxicological hazards associated with the molecule itself.
What do the scientific studies on Cardarine show?
Short-term metabolic studies in humans
One of the randomized studies conducted using a double-blind method analyzed GW501516, a separate PPARα agonist, and placebo.
The study involved 18 men, six in each group.
Over two weeks, parameters related to lipids, fat content in the liver, and indicators of fatty acid metabolism were evaluated.
The observed changes indicated short-term physiological activity of the substance.
However, the number of participants and the duration of observation were clearly insufficient to confirm the prevention of cardiovascular diseases or a beneficial long-term balance of benefits and risks. 5
In a separate cross-sectional study, 13 men with dyslipidemia and abdominal obesity participated.
The researchers used six-week treatment periods, analyzing the production and removal of lipoproteins from the body.
The results provided information about possible changes in the lipid profile.
The kinetics of lipoprotein particles, however, are not the same as clinical endpoints such as fewer heart attacks or longer life expectancy. 6
Another publication described a 12-week placebo-controlled study involving 268 people with low HDL cholesterol levels, and an exploratory study involving 37 participants.
Changes in several lipid and apolipoprotein parameters were observed.
A larger number of participants strengthens the evidence for short-term biochemical activity.
However, it does not resolve the issue of delayed toxic effects that cannot be reliably detected in a short metabolic study. 7
Distinguishing between a change in a biomarker and a clinical benefit is of fundamental importance.
A more favorable laboratory result may justify further testing.
However, it cannot be presented as proven disease prevention if such results have not been evaluated.
Studies on fitness and endurance in animals
In experiments on mice, the effect of PPARδ signaling on endurance training and metabolic adaptation was analyzed.
The widely cited 2008 study included experiments with a PPARδ agonist and a separate AMPK activator known as AICAR.
The results obtained for AICAR should not be attributed to Cardarine simply because both substances appear in the same publication. 8
Later studies in mice concerned the selection of energy substrates and the conservation of glucose during prolonged exercise.
The results support the importance of PPARδ-related signaling in endurance physiology under specific experimental conditions.
However, they do not confirm that the same intervention improves athletic performance in humans or can safely replace training. 9
Parameters studied in animals, such as running distance or the use of energy substrates, also answer questions other than measurements of human strength, athletic performance, body composition, or long-term health.
Cancerogenicity in rodents and concerns regarding the development of the substance
One of the most important elements of the history of GW501516 are the serious safety signals derived from toxicological studies on animals.
The Singapore Health Sciences Authority reports that cancer has been found in safety studies conducted on mice and rats. The authority also warns of the risks associated with products containing this substance. 2
These observations do not allow for calculating the exact individual risk of developing cancer in humans.
However, they constitute significant evidence of a potential threat.
Both the claim that every exposure inevitably causes cancer and the rejection of animal studies results solely because the long-term risk in humans has not been quantified would be incorrect.
Australia’s regulatory decision of 2018 provides additional historical context. It included placing Cardarine in Schedule 10.
However, the current legal status in a specific country must be checked separately, rather than being derived from a previous decision of a foreign authority. 10
The emergence of new cellular or animal publications does not mean that the clinical development of GW501516 has been resumed or that previous toxicological issues have been resolved.
The substance can still serve as an experimental tool, even though its usefulness as a medicine has not been demonstrated.
How does Cardarine affect PPARδ signaling?
PPARδ is a nuclear receptor involved in the regulation of gene expression.
Studies on GW501516 analyzed changes related to the oxidation of fatty acids, the use of glucose, and lipoprotein metabolism.
Unlike many peptide hormones that act on the surface receptors of cells, Cardarine is studied in the context of a mechanism related to the nuclear receptor. 5 6
Increased lipid oxidation is not equivalent to a sustained reduction in the amount of adipose tissue.
It describes the metabolic process measured under specific conditions.
Long-term changes in body composition depend on many additional factors and require direct evaluation.
Similarly, the change in the way mice use energy substrates during exercise does not confirm the health benefits in humans.
An appropriate clinical study would have to measure the appropriate parameters, taking into account training, diet, and other factors.
The interpretation of mechanistic studies should also avoid presenting the results selectively.
Receptors can affect many tissues and biological processes.
Therefore, a seemingly beneficial metabolic change does not prove that the entire body is protected from harmful effects.
The results of toxicological studies remain relevant even when the metabolic mechanism is scientifically interesting.
The most important limitations of the evidence regarding Cardarine
Long-term clinical benefits have not been confirmed
The studies described involving humans primarily concerned short-term metabolic changes.
They provide information about selected biomarkers and physiological processes.
However, they do not confirm sustained reduction in fat tissue, muscle growth, safe improvement in endurance, reduction in cardiovascular events, or increased lifespan.
Long-term safety remains a serious problem
The results of carcinogenicity studies in animals cannot be invalidated by citing short-term studies in humans.
The study, which lasted several weeks, was not designed to rule out any damage that might require longer exposure or observation.
The available evidence does not allow for determining a safe regimen for self-administration or a safe exposure threshold.
Animal results do not determine human performance
Exercise studies in mice provide knowledge about biological mechanisms.
However, they do not determine the effectiveness in humans, the safety of exposure, or the results in sports.
Translating such observations into dosage recommendations or use cycles would go beyond the available evidence.
The quality of the product and the toxicity of the substance itself are separate issues.
Even proper analytical identification does not confirm a favorable balance of benefits and risks.
In turn, an unverified online product introduces additional uncertainty regarding the actual composition.
Both the quality of the specific product and the risks associated with the molecule itself are important.
Anti-doping regulations are not clinical efficacy studies
The WADA ban constitutes a binding sporting regulation, but it is not a direct measure of the magnitude of the improvement in athletic performance in humans.
The regulations and scientific evidence should be presented separately, although both issues are important for understanding Cardarine. 4
Overall, these restrictions mean that Cardarine can be properly described as a biologically active substance, but not as a safe or approved therapy.
Frequently asked questions about Cardarine
1. Does Cardarine mean a specific substance?
Usually it is so. The name Cardarine refers to the GW501516 molecule. Chemical identifiers allow combining different variants of the name, but they do not confirm the authenticity of a particular product. Therefore, the defined scientifically tested substance and the content of the online offer must be evaluated separately. 1 The presence of many codes in the literature should not be interpreted as evidence that several distinct chemically distinct products have been clinically verified.
2. What do the available studies on Cardarine confirm?
The studies confirm the biological activity associated with PPARδ and short-term changes in metabolic biomarkers in humans. They do not confirm long-term clinical benefits or safe use in sports, and the serious toxicological findings obtained in animals remain significant. A balanced conclusion must take into account both the observed activity and the unresolved safety issues. 7 2 The alarm signal detected in rodents is a fundamental element of the assessment that should not be overlooked when discussing metabolic results.
3. Is Cardarine a peptide?
No. Its confirmed structure corresponds to a non-peptide, small molecule organic compound. Cardarine does not have an amino acid sequence or peptide backbone. Placing it in the peptide vendor’s catalog does not change this classification, therefore the term „Cardarine peptide” is incorrect. 1 The category selected by the store does not change the chemical definition of a peptide.
4. Is Cardarine a SARM?
No. Cardarine is a PPARδ agonist, not an androgen receptor modulator. The common sales category with SARMs does not mean a common mechanism of action. The interpretation of studies and safety should be based on the actual substance and its molecular target, not on marketing terminology. 1 The difference between PPARδ activation and androgen receptor modulation is of fundamental pharmacological importance.
5. Are GW1516 and GW501516 two different drugs?
No. These are Cardarine nomenclature variants used, among other places, in official anti-doping sources. Searching for both designations makes it easier to find documents, but it should not lead to double counting the same substance or the same studies. 4 Accurate chemical identifiers and study numbers help confirm the consistency of sources, especially when publications use different versions of the record.
6. Does an increase in HDL cholesterol levels indicate a reduction in the number of heart attacks?
No. A change in a biomarker is not equivalent to a confirmed clinical result. A larger study in humans evaluated lipid parameters, not the frequency of cardiovascular events. The results support the hypothesis of biochemical activity, but a claim regarding the prevention of heart attacks would require appropriate clinical studies. 7 Such studies would have to involve a sufficient number of participants and a sufficiently long observation period.
7. Does increased lipid oxidation confirm sustained fat tissue reduction?
No. These are two different parameters. The short-term metabolic study in humans focused on the use of energy substrates and related indicators, rather than a definitive assessment of long-term fat loss. 5 Confirmation of a lasting change in body composition requires direct, controlled measurements conducted over an appropriately long period of time. The result regarding the use of substrates during the test does not replace such data.
8. Has it been confirmed that Cardarine safely improves endurance in humans?
No. The studies discussed in this review do not support this conclusion. The most important endurance experiments were conducted in mice, while studies in humans focused primarily on metabolism. 8 9 Transferring the results of endurance tests in rodents to claims of safe improvement in human performance goes beyond the available evidence. Direct studies in humans would be needed.
9. Does the term „exercise mimetic” mean that Cardarine replaces physical exercise?
No. This term refers to the study of selected exercise-related pathways or adaptations, rather than simulating all the effects of training. Basic experiments also included various substances and their effects on physical activity. 8 The term should be considered as a research concept, rather than a confirmation of clinical equivalence with exercise. Physical activity affects many systems of the body, which are not described by a single receptor or signal measurement.
10. Do the results of cancer research in animals mean that every person who uses Cardarine will develop cancer?
No. The results of toxicology tests on animals do not allow for predicting the individual risk in a specific person. However, tumors reported in safety studies in rodents constitute a serious warning of danger and cannot be dismissed simply because the risk in humans has not been accurately assessed. 2 Uncertainty regarding the magnitude of the risk does not mean its absence. Proper interpretation takes into account serious animal results and the limitations of their quantitative transfer to humans.
11. Can short-term studies in humans rule out the long-term risk of cancer?
No. The limited time of exposure and observation does not allow the delayed consequences to be adequately ruled out. Lipid studies in humans addressed different questions than the chronic carcinogenicity studies. 7 Their duration and evaluated parameters make it impossible to treat them as evidence that the results of animal safety studies are irrelevant. Short-term tolerance does not resolve the risks that may become apparent much later.
12. Have the studies determined a safe cycle of Cardarine use?
No. The evidence discussed does not support a safe self-administration regimen of Cardarine with an acceptable risk profile. The experimental schedule used in the study is not an approved protocol for personal use. Converting the amounts of the substance between animals and humans also does not resolve the problem of missing safety data. The scientific results should be presented without being converted into instructions for use. Based on the studies discussed, no dose or schedule can be considered safe for self-administration.
13. Is Cardarine banned in sports?
Yes. The WADA list for 2026 lists GW1516/GW501516 in category S4.4.1 covering PPARδ agonists and prohibits its use both during and outside of competitions. 4 This is an anti-doping regulation, separate from national pharmaceutical and criminal law. Athletes should follow the current rules applicable to their discipline. The anti-doping classification is not equivalent to a decision to register a drug or restrict its sale in a specific country.
14. Does the substance identifier in the FDA database mean Cardarine is approved?
No. The UN number serves to identify the substance, not to allow medicines to be marketed. The entry for GW-501516 helps determine the chemical identity, but does not confirm the approved indication or the safe formulation. 3 The registration of the identity of the substance and the approval of the medicinal product answer different questions. The identification entry itself does not constitute a clinical assessment of the suitability of the finished product.
15. Can a purity test eliminate the risks associated with Cardarine?
No. A purity study can provide information about the composition of the sample, but it does not remove the biological effects of the target substance. Even a chemically pure compound can exhibit serious toxicity. Assessing the quality of a product and assessing clinical safety are separate issues that cannot be substituted for each other. Proper analytical characterization does not eliminate the hazards resulting from the action of the molecule itself.
16. Do new laboratory publications mean the resumption of clinical development of Cardarine?
No. The substance may remain a useful experimental tool after the end of the clinical development program. The new publication regarding cells or animals does not confirm the resumption of human studies, the obtaining of regulatory approval, or the resolution of previous safety issues. The status of development should be determined based on the relevant documents of the research program and regulatory records. New mechanistic experiments should be distinguished from completed clinical efficacy and safety studies.
17. Can the results of studies with other PPAR agonists be applied to Cardarine?
Not automatically. Substances acting on related receptors can differ in selectivity, exposure, and safety. Even studies concerning the same receptor family require interpretation specific to the particular compound. A common pharmacological mechanism may justify a new research hypothesis, but it does not allow for transferring the approval of a drug or the assessment of the benefit-risk balance from one substance to another. Clinical and toxicological evaluation must take into account the specific molecule.
Applications
Cardarine (GW501516) is a chemically defined, non-peptide agonist of PPARδ. It is neither an SARM nor a protein.
Studies involving humans have shown short-term metabolic changes, while animal experiments have provided information about mechanisms related to physical endurance.
At the same time, the results of carcinogenicity studies in rodents constitute a serious safety problem.
None of the cited sources confirms the safe improvement of sports performance, the verified long-term treatment that reduces adipose tissue, nor the favorable clinical balance of benefits and risks.
Scientific interpretation should therefore clearly distinguish molecular identity, metabolic biomarkers, exercise performance results in animals, toxicology, and anti-doping regulations.
Educational, medical and anti-doping reservations
The article is of purely scientific informational nature and does not constitute medical advice, diagnosis, or recommendations for the purchase or use of Cardarine (GW501516). The substance is not a peptide, and available evidence does not confirm its safety or efficacy as an approved treatment or a means to improve athletic performance. Toxicological studies in animals have revealed serious risks associated with tumors, which short-term metabolic studies in humans do not rule out. GW501516 is on the WADA Prohibited Substances List for 2026, both during and outside of competition. The chemical identifier, analysis certificate, or online offer do not confirm the safety of the product. Health issues and the current legal status should be consulted with appropriate specialists and verified in official sources.
References
- National Center for Biotechnology Information. (n.d.). PubChem compound summary for CID 9803963, GW 501516. Retrieved October 23, 2026, from https://pubchem.ncbi.nlm.nih.gov/compound/GW-501516
- Health Sciences Authority. (2017, October 20). HSA alert: Bodybuilding products sold online contain harmful substances. https://www.hsa.gov.sg/announcements/hsa-alert-bodybuilding-products-sold-online-contain-harmful-substances/
- U.S. Food and Drug Administration. (n.d.). GW-501516 (UNII: 7I2HA1NU22) [Substance identity record]. Retrieved October 23, 2026, from https://precision.fda.gov/uniisearch/srs/unii/7I2HA1NU22
- World Anti-Doping Agency. (2025). The 2026 prohibited list: International standard of the World Anti-Doping Code. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
- Risérus, U., Sprecher, D., Johnson, T., Olson, E., Hirschberg, S., Liu, A., Fang, Z., Hegde, P., Richards, D., Sarov-Blat, L., Strum, J. C., Basu, S., Cheeseman, J., Fielding, B. A., Humphreys, S. M., Danoff, T., Moore, N. R., Murgatroyd, P., O’Rahilly, S., … Karpe, F. (2008). Activation of peroxisome proliferator-activated receptor (PPAR)delta promotes reversal of multiple metabolic abnormalities, reduces oxidative stress, and increases fatty acid oxidation in moderately obese men. Diabetes, 57(2), 332–339. https://doi.org/10.2337/db07-1318
- Ooi, E. M., Watts, G. F., Sprecher, D. L., Chan, D. C., & Barrett, P. H. (2011). Mechanism of action of a peroxisome proliferator-activated receptor (PPAR)-delta agonist on lipoprotein metabolism in dyslipidemic subjects with central obesity. The Journal of Clinical Endocrinology & Metabolism, 96(10), E1568–E1576. https://doi.org/10.1210/jc.2011-1131
- Olson, E. J., Pearce, G. L., Jones, N. P., & Sprecher, D. L. (2012). Lipid effects of peroxisome proliferator-activated receptor-δ agonist GW501516 in subjects with low high-density lipoprotein cholesterol: characteristics of metabolic syndrome. Arteriosclerosis, Thrombosis, and Vascular Biology, 32(9), 2289–2294. https://doi.org/10.1161/ATVBAHA.112.247890
- Narkar, V. A., Downes, M., Yu, R. T., Embler, E., Wang, Y. X., Banayo, E., Mihaylova, M. M., Nelson, M. C., Zou, Y., Juguilon, H., Kang, H., Shaw, R. J., & Evans, R. M. (2008). AMPK and PPARdelta agonists are exercise mimetics. Cell, 134(3), 405–415. https://doi.org/10.1016/j.cell.2008.06.051
- Fan, W., Waizenegger, W., Lin, C. S., Sorrentino, V., He, M. X., Wall, C. E., Li, H., Liddle, C., Yu, R. T., Atkins, A. R., Auwerx, J., Downes, M., & Evans, R. M. (2017). PPARδ promotes running endurance by preserving glucose. Cell Metabolism, 25(5), 1186–1193.e4. https://doi.org/10.1016/j.cmet.2017.04.006
- Therapeutic Goods Administration. (2018, April 10). Publication of final decisions amending, or not amending, the current Poisons Standard (Section 1.2, Cardarine, p. 8) [FOI copy]. https://www.tga.gov.au/sites/default/files/2023-05/foi-4359-03.PDF