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Background And Regulatory History — Background and Details

By Editorial Desk · published 2025-10-19 · last reviewed 2025-11-03 · Topic

If you have been reading about PPARδ agonist and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.

Updated 2025-11-03. Numbers and descriptions here follow the published literature rather than marketing material.

Background and Regulatory History

GW501516 acts on PPARδ, a nuclear receptor that helps regulate fatty acid oxidation and energy homeostasis. In animal studies, activation of this receptor was associated with increased endurance and changes in lipid metabolism. Human trials examined effects on blood lipids and other metabolic markers, but the compound did not advance to approval. Rodent studies later reported tumors in multiple tissues at doses used in those experiments. Whether those findings translate to human risk remains uncertain, and the clinical relevance of the animal data is still debated.

Regulatory bodies treat GW501516 as a prohibited substance in competitive sport. The World Anti-Doping Agency added it to the prohibited list, and it falls under classes covering metabolic modulators and hormone-related agents. It is not approved by drug regulators for human use, and it is not a lawful dietary supplement. Products sold under the cardarine name may contain unlisted ingredients or different compounds. Because no approved product exists, quality and identity are not guaranteed by pharmaceutical manufacturing standards.

Cardarine is a common name for the investigational chemical GW501516, also written GW-1516. It was developed as a peroxisome proliferator-activated receptor delta agonist for metabolic conditions such as dyslipidemia. Early research focused on lipid handling and energy use in skeletal muscle and other tissues. The compound was never approved as a medicine. In public discussion, it is often grouped with performance-enhancing substances, although its receptor target differs from that of anabolic steroids or selective androgen receptor modulators. Regulatory and health authorities have issued warnings about its use.

Mechanism and Laboratory Detection

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.

GW501516 binds and activates PPARδ, a nuclear receptor that influences transcription of genes involved in fatty acid oxidation and energy use. Activation shifts some metabolic pathways in preclinical models, which is why the compound has been studied for lipid disorders and exercise-related endpoints. The exact downstream effects in humans are incompletely mapped. PPARδ is expressed in many tissues, including skeletal muscle, liver, and adipose tissue, so broad activation may have varied consequences. Researchers continue to examine how selective or partial activation might alter the balance between benefits and risks.

Cardarine at a glance

PropertyValueNotes
Common nameCardarineCommon internet and media name.
Research codeGW501516Also written GW-1516.
Drug classPPARδ agonistNot a selective androgen receptor modulator.
Development statusDiscontinuedClinical development halted after rodent cancer findings.
Regulatory statusProhibited in sportListed by WADA; not approved as medicine.

Regulation and Analytical Detection

Anti-doping laboratories detect GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be used in some programs. Detection depends on factors such as dose, timing, metabolism, and the sensitivity of the assay. Published methods describe limits of detection in the low nanogram per milliliter range for related compounds. Exact detection windows are not fixed for all situations and remain an area of ongoing study.

Products sold as cardarine have been found to contain incorrect compounds, variable amounts, or no active ingredient at all. Independent testing is required to verify identity and purity. Common analytical approaches include high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance for structural confirmation. These methods can distinguish GW501516 from related PPAR agonists and from unrelated steroids. For regulators and researchers, such verification is central to interpreting both biological results and adverse event reports.

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Mechanism and Detection Methods

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.

Identity and Pharmacological Classification

Cardarine is a common name for GW501516, also GW-1516, a synthetic compound developed as a peroxisome proliferator-activated receptor delta (PPARδ) agonist. It belongs to a class of agents that modulate gene transcription related to lipid and energy metabolism. The compound was studied in preclinical and early clinical research for metabolic and cardiovascular conditions, but it did not progress to approved therapeutic use. Its name appears in fitness and sports contexts despite not being approved as a drug.

PPARδ is a nuclear receptor that influences transcription of genes involved in fatty acid oxidation, lipid transport, and energy homeostasis. GW501516 binds and activates this receptor with high selectivity relative to PPARα and PPARγ in laboratory assays. Activation alters expression of target genes in skeletal muscle, liver, and adipose tissue in animal models. The exact clinical consequences of these changes in humans remain incompletely characterized, and observed effects in animals do not establish therapeutic benefit or safety.

Published studies have examined GW501516 in animal models of obesity, insulin resistance, and exercise endurance. Early human trials reportedly ended, and development was discontinued after preclinical findings raised concerns about cancer in some rodent studies. Regulatory agencies have not approved cardarine for any medical use. Its availability through non-pharmaceutical channels raises questions about identity, purity, and legal status that are separate from its laboratory pharmacology. Those questions are often addressed through analytical testing rather than assumptions about product labels.

Background and Regulatory Status

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.

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.

Reference notes

=== Synthesis === Mescaline was the first ever psychedelic drug synthesized by chemists. Ernst Späth's 1919 total synthesis started from 3,4,5-trimethoxy­benzoyl chloride. Several approaches using different starting materials have been developed since, including the following:

=== Designed proteins === Numerous protein structures are the result of rational design and do not exist in nature. Proteins can be designed from scratch (de novo design) or by making calculated variations on a known protein structure and its sequence (known as protein redesign). Rational protein design approaches make protein-sequence predictions that will fold to specific structures. These predicted sequences can then be validated experimentally through methods such as peptide synthesis, site-directed mutagenesis, or Artificial gene synthesis.

==== In pregnancy ==== Pregnant women with opioid use disorder can also receive treatment with methadone, naltrexone, or buprenorphine. Buprenorphine appears to be associated with more favorable outcomes compared to methadone for treating opioid use disorder (OUD) in pregnancy. Studies show that buprenorphine is linked to lower risks of preterm birth, greater birth weight, and larger head circumference without increased harm. Compared to methadone, it consistently results in improved birth weight and gestational age, though these findings should be interpreted with caution due to potential biases. Buprenorphine use correlates with a lower risk of adverse neonatal outcomes, with similar risks of adverse maternal outcomes as methadone. Infants born to buprenorphine-treated mothers generally have higher birth weights, fewer withdrawal symptoms, and a lower likelihood of premature birth. They often require less treatment for neonatal abstinence syndrome and have mothers who are more likely to start treatment earlier in pregnancy, leading to longer gestations and larger infants.

=== Legal status === On 13 October 2022, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Locametz, intended for the diagnosis of prostate cancer. The applicant for this medicinal product is Novartis Europharm Limited. Locametz was approved for medical use in the European Union in December 2022.

Lactobacillus bulgaricus is the main bacterium used for the production of yogurt. It also plays a crucial role in the ripening of some cheeses, as well as in other processes involving naturally fermented products. It is defined as homofermentive lactic acid bacteria due to lactic acid being the single end product of its carbohydrate digestion. It is also considered a probiotic. It is a gram-positive rod that may appear long and filamentous. It is non-motile and does not form spores. It is also non-pathogenic. It is regarded as aciduric or acidophilic, since it requires a low pH (around 5.4–4.6) to grow effectively. In addition, it is anaerobic. As it grows on raw dairy products, it creates and maintains the acidic environment that it needs to thrive via its production of lactic acid. In addition, it grows optimally at temperatures of 40–44 °C under anaerobic conditions. It has complex nutritional requirements which vary according to the environment. These include carbohydrates, unsaturated fatty acids, amino acids, and vitamins. First identified in 1905 by the Bulgarian doctor Stamen Grigorov by isolating what later termed Lactobacillus Bulgaricus from a Bulgarian yogurt sample, the bacteria can be found naturally in the gastrointestinal tract of mammals living in Sofia region and along the Balkan Mountain (Stara Planina) mesoregion of Balkan peninsula. One strain, Lactobacillus bulgaricus GLB44, is extracted from the leaves of the Galanthus nivalis (snowdrop flower) in Bulgaria. The bacterium is also grown artificially in many countries.

Sources: en.wikipedia.org

Notes from published material

Some parasitic algae (e.g., the green algae Prototheca and Helicosporidium, parasites of metazoans, or Cephaleuros, parasites of plants) were originally classified as fungi, sporozoans, or protistans of incertae sedis, while others (e.g., the green algae Phyllosiphon and Rhodochytrium, parasites of plants, or the red algae Pterocladiophila and Gelidiocolax mammillatus, parasites of other red algae, or the dinoflagellates Oodinium, parasites of fish) had their relationship with algae conjectured early. In other cases, some groups were originally characterized as parasitic algae (e.g., Chlorochytrium), but later were seen as endophytic algae. Some filamentous bacteria (e.g., Beggiatoa) were originally seen as algae. Furthermore, groups like the apicomplexans are also parasites derived from ancestors that possessed plastids, but are not included in any group traditionally seen as algae.

Ohanin, a minor vespryn protein component specific to this species, causes hypolocomotion and hyperalgesia in experimental mice. It is believed that it contributes to neurotoxicity on the central nervous system of the victim.

Wellcome (Chinese: 惠康; Jyutping: wai6 hong1; pinyin: Huìkāng) is a supermarket chain owned by British conglomerate Jardine Matheson Holdings via its DFI Retail Group subsidiary. The Wellcome supermarket chain is one of the two largest supermarket chains in Hong Kong, the other being ParknShop. DFI formerly operated supermarkets in the Philippines and Taiwan (Chinese: 頂好; pinyin: Dǐnghǎo) under the Wellcome name, and has various other supermarkets around Asia including Market Place, Cold Storage, Hero and Giant.

=== Effects on inflammation === PGLYRP2 directly and indirectly affects inflammation and plays a role in maintaining anti- and pro-inflammatory homeostasis in the intestine, skin, joints, and brain. Hydrolysis of peptidoglycan by PGLYRP2 diminishes peptidoglycan's pro-inflammatory activity. This effect is likely due to amidase activity of PGLYRP2, which separates the stem peptide from MurNAc in peptidoglycan and destroys the motif required for the peptidoglycan-induced activation of NOD2 (nucleotide-binding oligomerization domain-containing protein 2), one of the proinflammatory peptidoglycan receptors. PGLYRP2-deficient mice are more susceptible than wild type mice to dextran sodium sulfate (DSS)-induced colitis, which indicates that PGLYRP2 protects mice from DSS-induced colitis. Intestinal microbiome is important for this protection, because this increased sensitivity to colitis could be transferred to wild type germ-free mice by microbiome transplant from PGLYRP2-deficient mice. PGLYRP2-deficient mice are more susceptible than wild type mice to the development of experimentally induced psoriasis-like inflammation, which indicates that PGLYRP2 is anti-inflammatory and protects mice from this type of skin inflammation. This pro-inflammatory effect in PGLYRP2-deficient mice is due to the increased numbers and activity of T helper 17 (Th17) cells and decreased numbers of T regulatory (Treg) cells. PGLYRP2-deficient mice are more susceptible than wild type mice to S.

Sources: en.wikipedia.org

Frequently asked questions

Is cardarine a selective androgen receptor modulator?

No. Cardarine is a PPARδ agonist, while selective androgen receptor modulators act on androgen receptors. The two classes differ in receptor target and downstream effects.

Why did clinical development stop?

Preclinical rodent studies reported cancers, including liver and bladder tumors, at tested doses. The human relevance of those findings is uncertain, but development was discontinued. No approved human product resulted.

Is cardarine approved for medical use?

No. It remains an investigational compound without approved therapeutic labeling. Sports regulators prohibit its use, and health agencies have warned against consuming it.

How is cardarine detected in samples?

Anti-doping and clinical laboratories commonly use liquid chromatography-tandem mass spectrometry. The method can identify GW501516 and its metabolites in urine or blood. Detection depends on sample timing and the amount present.

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