A practical reference on PPARδ: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-13. Anything still debated is marked as such rather than presented as settled.
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.
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 |
|---|---|---|
| Appearance | White to off-white solid | Typical form of reference material |
| Solubility | Low in water; soluble in DMSO | Used to prepare stock solutions |
| Typical storage | -20 °C, desiccated, protected from light | Common laboratory practice |
| Analytical method | LC-MS/MS | Detects parent compound and metabolites |
| Common test matrix | Urine or blood | Used in anti-doping analysis |
Cardarine is prohibited in competitive sport under the World Anti-Doping Agency code, where it is classified as a metabolic modulator. It is not approved as a prescription medicine in the United States, European Union, or other major markets. Regulatory action has focused on its presence in sports and in products marketed as research chemicals. Because it has no accepted medical indication, supply is often unregulated. This status creates legal and safety uncertainties for anyone who encounters the substance.
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.
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.
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.
Neuropeptide SF (NPSF) (RFRP-1) – agonist of the NPFF1 and NPFF2 receptors (EC50 = 29 nM and 0.0011 nM, respectively) RFRP-2 – does not bind to either of the NPFF receptors; no known biological activity Neuropeptide VF (NPVF) (RFRP-3) – agonist of the NPFF1 receptor (IC50 = 0.7 nM) NPSF and NPVF, originally referred to as the RFamide-related peptides RFRP-1 and RFRP-3, respectively, are the mammalian homologs of the avian neuropeptide gonadotropin-inhibitory hormone (GnIH). The mammalian NPVF and avian GnIH genes, along with their aforementioned peptide products, were discovered concurrently in 2000. Similarly to the avian GnIH neuropeptide, NPSF and NPVF have been found to potently inhibit gonadotropin secretion. Moreover, a potent and selective antagonist of the NPFF receptors, RF9, has been reported to possess "very strong" gonadotropin-releasing effects in vivo in male and female mice.
=== Activity profile === Flibanserin acts as a full agonist in the frontal cortex and the dorsal raphe nucleus, but only as a partial agonist in the CA3 region of the hippocampus of the 5-HT1A receptor (serotonin receptor) (Ki = 1 nM in CHO cells, but only 15–50 nM in cortex, hippocampus and dorsal raphe) and, with lower affinity, as an antagonist of the 5-HT2A receptor (Ki = 49 nM) and antagonist or very weak partial agonist of the D4 receptor (Ki = 4–24 nM, Ki = 8–650 nM). Flibanserin demonstrates selectivity for postsynaptic 5-HT1A receptors. Despite the much greater affinity of flibanserin for the 5-HT1A receptor, and for reasons that are unknown (although it might be caused by the competition with endogenous serotonin), flibanserin occupies the 5-HT1A and 5-HT2A receptors in vivo with similar percentages. Flibanserin also has low affinity for the 5-HT2B receptor (Ki = 89.3 nM) and the 5-HT2C receptor (Ki = 88.3 nM), both of which it behaves as an antagonist of. Flibanserin preferentially activates 5-HT1A receptors in the prefrontal cortex, demonstrating regional selectivity, and has been found to increase dopamine and norepinephrine levels and decrease serotonin levels in the rat prefrontal cortex, actions that were determined to be mediated by activation of the 5-HT1A receptor. As such, flibanserin has been described as a norepinephrine–dopamine disinhibitor (NDDI). The proposed mechanism of action refers to the Kinsey dual control model of sexual response.
=== 1972 === February 21: Nixon visits China, the first visit by a U.S. president since the establishment of the People's Republic of China. March 30: Viet Cong goes to the offensive in South Vietnam, only to be repulsed by the South Vietnamese regime with major American air support. April: The Ikiza mass killings occurred in Burundi committed by the Tutsi-dominated army against the Hutus. April 10: Biological Weapons Convention is signed banning the production, development and stockpiling of biological weapons. May 22: Richard Nixon attends Moscow Summit (1972), becoming the first US president to visit Moscow. May 26: Strategic Arms Limitation Talks (SALT I) agreement signals the beginning of détente between the U.S. and USSR. September 1: Bobby Fischer defeats Russian Boris Spassky in a chess match in Reykjavík, Iceland, becoming the first official American chess champion (see Match of the Century). September 2–28: The Summit Series, an ice hockey tournament between Canada and Soviet Union. September 21: Philippine president Ferdinand Marcos declares martial law, officially in response to the growing communist threat in the Philippines. September 26: The short border war occurred between the Yemen Arab Republic and South Yemen. December 18: Richard Nixon announces the beginning of a massive bombing campaign in North Vietnam.
Sources: en.wikipedia.org
Senator, I am not now, nor have I ever been, an oil trader—and neither has anyone on my behalf. I have never seen a barrel of oil, owned one, bought one, sold one—and neither has anyone on my behalf. Now I know that standards have slipped in the last few years in Washington, but for a lawyer you are remarkably cavalier with any idea of justice. I am here today but last week you already found me guilty. You traduced my name around the world without ever having asked me a single question, without ever having contacted me, without ever having written to me or telephoned me, without any attempt to contact me whatsoever, and you call that justice. Galloway countered the charges by claiming they were politically motivated and a "smokescreen". He accused Coleman and other pro-war politicians of covering up the "theft of billions of dollars of Iraq's wealth". He claimed this happened "on your watch" under the post-invasion Coalition Provisional Authority, and was committed by "Halliburton and other American corporations ... with the connivance of your own government".
HMF can be found in low amounts in honey, fruit-juices and UHT-milk. Here, as well as in vinegars, jams, alcoholic products or biscuits, HMF can be used as an indicator for excess heat-treatment. For instance, fresh honey contains less than 15 mg/kg—depending on pH-value and temperature and age, and the codex alimentarius standard requires that honey have less than 40 mg/kg HMF to guarantee that the honey has not undergone heating during processing, except for tropical honeys which must be below 80 mg/kg. Higher quantities of HMF are found naturally in coffee and dried fruit. Several types of roasted coffee contained between 300 – 2900 mg/kg HMF. Dried plums were found to contain up to 2200 mg/kg HMF. In dark beer 13.3 mg/kg were found, bakery-products contained between 4.1 – 151 mg/kg HMF. It can be found in glucose syrup. HMF can form in high-fructose corn syrup (HFCS), levels around 20 mg/kg HMF were found, increasing during storage or heating. This is a problem for American beekeepers because they use HFCS as a source of sugar when there are not enough nectar sources to feed honeybees, and HMF is toxic to them. Adding bases such as soda ash or potash to neutralize the HFCS slows the formation of HMF. Depending on production-technology and storage, levels in food vary considerably. To evaluate the contribution of a food to HMF intake, its consumption-pattern has to be considered. Coffee is the food that has a very high relevance in terms of levels of HMF and quantities consumed. HMF is a natural component in heated food but usually present in low concentrations.
aminoacyl-tRNA synthetase Also tRNA-ligase. Any of a set of enzymes which catalyze the transesterification reaction that results in the attachment of a specific amino acid (or a precursor) to one of its cognate transfer RNA molecules, forming an aminoacyl-tRNA. Each of the 20 different amino acids used in the genetic code is recognized and attached by its own specific synthetase enzyme, and most synthetases are cognate to several different tRNAs according to their specific anticodons.
Sources: en.wikipedia.org
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.
PPARδ is a nuclear receptor that regulates genes linked to fatty acid oxidation and energy metabolism. Activation can alter lipid handling and energy use in experimental models. The full range of effects in humans is still under study.
The solid compound is generally stable when kept cold, dry, and protected from light. Solutions may degrade faster, so laboratory protocols often specify fresh preparation or cold storage. Stability can depend on solvent, concentration, and container.
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.