Everything below concerns LC-MS/MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-01-11. Numbers and descriptions here follow the published literature rather than marketing material.
Because cardarine is not an approved medicine, no pharmacopeial monograph defines its identity, purity, or storage requirements. Laboratories typically rely on in-house methods and reference standards when testing materials labeled as GW501516. Certificates of analysis may report purity and identity for a specific batch, but their scope varies and they do not guarantee safety or legal status. Independent verification can include high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance, and elemental analysis. The distinction between research chemical labeling and human use is significant because quality standards and oversight differ.
Cardarine can be detected in biological samples and product materials using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method separates compounds by chromatography and identifies them by mass-to-charge transitions, allowing low-level detection in urine or blood. Sample preparation often involves enzymatic hydrolysis, solid-phase extraction, or protein precipitation. Certified reference materials and isotope-labeled internal standards improve quantification. Detection windows depend on metabolism, matrix, and assay sensitivity, so no single universal window applies.
Regulatory treatment of cardarine differs by context and jurisdiction. In competitive sport, the World Anti-Doping Agency lists PPARδ agonists, including GW501516, as prohibited at all times. Outside sport, it lacks approval as a prescription medicine in major drug markets, and products sold for human consumption may be treated as unapproved drugs. Some countries also restrict importation or sale through general consumer protection and medicines laws. These classifications affect availability, testing, and legal risk without establishing therapeutic value.
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 |
|---|---|---|
| WADA classification | S4 Hormone and Metabolic Modulators | Prohibited at all times in sport. |
| Drug approval status | Not approved in major jurisdictions | No accepted therapeutic indication. |
| Common detection method | LC-MS/MS | Detects parent compound and metabolites. |
| Typical test matrix | Urine or blood | Urine is common in anti-doping testing. |
| Product labeling | Research chemical or supplement | Often not independently verified. |
Laboratory detection of GW501516 commonly uses liquid chromatography coupled with tandem mass spectrometry. The method can identify the parent compound or its metabolites in urine and blood after sample cleanup. Protein precipitation, solid-phase extraction, or enzymatic hydrolysis may precede analysis, depending on the matrix. Reference standards are required for accurate quantification and confirmation. Because the compound is not approved, testing often occurs in anti-doping, forensic, or research settings rather than routine clinical care. Results are reported with limits of detection and quantification.
Stability of GW501516 depends on form, temperature, light exposure, and moisture. Solid reference material is typically stored frozen or refrigerated in a desiccator and protected from light. Solutions in organic solvents such as dimethyl sulfoxide are often kept frozen in aliquots to reduce freeze-thaw cycling. Aqueous solubility is low, so aqueous stock solutions can be difficult to prepare without cosolvents. Degradation may appear as changes in chromatographic purity or mass spectral signal. Stability studies are needed to establish shelf life for any specific preparation.
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.
The compound is typically described as a laboratory compound rather than a therapeutic product. Published reports have explored its role in lipid disorders, insulin sensitivity, and exercise metabolism, yet no major drug regulator has approved it for medical use. Commercial samples sold under the cardarine name may vary in purity and identity. Analytical confirmation is therefore necessary when the material is discussed in scientific or regulatory contexts. Its classification as a prohibited substance in sport further shapes how it is studied and reported.
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.
== Adverse effects == In clinical trials, the most common adverse effects of sildenafil use included headache, flushing, indigestion, nasal congestion, and impaired vision, including photophobia and blurred vision. Some sildenafil users have complained of seeing everything tinted blue (cyanopsia). This cyanopsia can be explained because sildenafil, while selective for PDE5, does have some affinity for PDE6, which is the phosphodiesterase found in the retina. Patients thus taking the drug may experience colorvision abnormalities. Some complained of blurriness and loss of peripheral vision. In July 2005, the US Food and Drug Administration (FDA) updated labeling for tadalafil (Cialis), vardenafil (Levitra), and sildenafil (Viagra) to reflect a small number of post-marketing reports of sudden vision loss, while acknowledging that "...it is not possible to determine whether these oral medicines for erectile dysfunction were the cause of the loss of eyesight or whether the problem is related to other factors such as high blood pressure or diabetes, or to a combination of these problems." A careful review of pooled data from clinical trials containing well documented information about the dose and duration of exposure to the drug for a large number of patients, yields no evidence for an increased risk of non-arteritic anterior ischemic optic neuropathy or other adverse ocular events associated with PDE5 inhibitor use.
== Mechanism of action == Like intravenous immunoglobulin therapy, ZMapp contains a mixture of neutralizing antibodies that confer passive immunity to an individual, enhancing the normal immune response, and is designed to be administered after exposure to the Ebola virus. Such antibodies have been used in the treatment and prevention of various infectious diseases and are intended to attack the virus by interfering with its surface and neutralizing it to prevent further damage.
==== Exfoliation with supercritical carbon dioxide ==== Liquid-phase exfoliation can also be done by a less-known process of intercalating supercritical carbon dioxide (scCO2) into the interstitial spaces in the graphite lattice, followed by rapid depressurization. The scCO2 intercalates easily inside the graphite lattice at a pressure of roughly 100 atm. Carbon dioxide turns gaseous as soon as the vessel is depressurized and makes the graphite explode into few-layered graphene. This method may have multiple advantages: being non-toxic, the graphite does not have to be chemically treated in any way before the process, and the whole process can be completed in a single step as opposed to other exfoliation methods.
Wood pulp made from birch gives relatively long and slender fibres for a hardwood. The thin walls cause the fibre to collapse upon drying, giving a paper with low bulk and low opacity. The birch fibres are, however, easily fibrillated and give about 75% of the tensile strength of softwood. The low opacity makes it suitable for making glassine. In India, the birch (Sanskrit: भुर्ज, bhurja) holds great historical significance in the culture of North India, where the thin bark coming off in winter was extensively used as writing paper. Birch paper (Sanskrit: भुर्ज पत्र, bhurja patra) is exceptionally durable and was the material used for many ancient Indian texts. The Roman period Vindolanda tablets also use birch as a material on which to write and birch bark was used widely in ancient Russia as notepaper (beresta) and for decorative purposes and even making footwear (lapti) and baskets.
Sources: en.wikipedia.org
=== Non-specific hydrophobic association === Amphitropic proteins associate with lipid bilayers via various hydrophobic anchor structures. Such as amphiphilic α-helixes, exposed nonpolar loops, post-translationally acylated or lipidated amino acid residues, or acyl chains of specifically bound regulatory lipids such as phosphatidylinositol phosphates. Hydrophobic interactions have been shown to be important even for highly cationic peptides and proteins, such as the polybasic domain of the MARCKS protein or histactophilin, when their natural hydrophobic anchors are present.
A genome-wide study of convergence published in 2013 analysed 22 mammal genomes and revealed that tens of genes have undergone the same replacements in echolocating bats and cetaceans, with many of these genes encoding proteins that function in hearing and vision. Both the aye-aye lemur and the striped possum have an elongated finger used to get invertebrates from trees. There are no woodpeckers in Madagascar or Australia where the species evolved, so the supply of invertebrates in trees was large. Castorocauda, a Jurassic Period mammal and beavers both have webbed feet and a flattened tail, but are not related. Prehensile tails evolved in a number of unrelated species marsupial opossums, their Australasian cousins, kinkajous, New World monkeys, tree-pangolins, tree-anteaters, porcupines, rats, skinks and chameleons, and the salamander Bolitoglossa. Pig form, large-headed, pig-snouted and hoofs are independent in true pigs in Eurasia, peccaries in South America and the extinct entelodonts. Tapirs and pigs look much alike, but tapirs are perissodactyls (odd-toed ungulates) and pigs are artiodactyls (even-toed ungulates). Filter feeding: baleen whales like the humpback and blue whale (mammals), the whale shark and the basking shark separately, the manta ray, the Mesozoic bony fish Leedsichthys, and the early Paleozoic anomalocaridid Aegirocassis have separately evolved ways of sifting plankton from marine waters. The monotreme platypus has what looks like a bird's beak (hence its scientific name Ornithorhynchus), but is a mammal.
Analogues of 4-HO-NiPT include 4-hydroxytryptamine (4-HT or 4-HO-T), 4-HO-MiPT (miprocin), 4-HO-DiPT (diprocin), psilocin (4-HO-DMT), norpsilocin (4-HO-NMT), 4-HO-NET, 4-HO-NPT, 4-HO-NALT, and 4-HO-NBnT, among others.
Sources: en.wikipedia.org
Anti-doping laboratories typically use LC-MS/MS to detect GW501516 and its metabolites in urine. The method is sensitive and can identify the compound at low concentrations. Detection depends on sample timing, metabolism, and the specific assay.
Legality varies by country and context. It lacks marketing approval as a medicine in major countries. Sports organizations prohibit its use at all times.
A certificate of analysis may report identity, purity, and testing methods for a specific batch. It does not guarantee safety or legal status. Independent verification can confirm whether the material matches the label.
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.