If you have been reading about fatty acid oxidation 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 2026-04-10. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Quality assessment for cardarine samples usually combines identity, purity, and impurity testing. Nuclear magnetic resonance spectroscopy and mass spectrometry can confirm molecular structure, while high-performance liquid chromatography estimates purity. Certificates of analysis from testing laboratories may list these results, but they do not establish safety or legality. In the absence of approved manufacturing, products sold online may contain the wrong compound, variable amounts, or unlisted contaminants. Independent verification is therefore central to analytical work and to interpreting any reported biological activity.
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.
| Property | Value | Notes |
|---|---|---|
| IUPAC name | {4-[({4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-5-yl}methyl)sulfanyl]phenoxy}acetic acid | Systematic name for GW501516 |
| CAS Registry Number | 317318-70-0 | Unique identifier for the parent compound |
| Molecular formula | C21H18F3NO3S2 | Includes carbon, hydrogen, fluorine, nitrogen, oxygen, and sulfur |
| Molecular weight | 453.5 g/mol | Approximate value for the neutral form |
| Appearance | White to off-white powder | Typical description for purified laboratory material |
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.
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.
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.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s 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.
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.
A persistent misconception is that cardarine is a fat-burning drug or a safe alternative to anabolic steroids. No approved therapeutic product exists, and human safety data are limited. The tumor findings in rodents remain a central concern in scientific reviews. Products sold online may contain inaccurate labels, impurities, or different compounds entirely, which complicates any assessment of effects. Independent testing of such products has reported frequent mislabeling. For these reasons, discussions in the literature emphasize risks and unknowns rather than benefits.
== Side effects == Side effects of tiagabine are dose-related. The most common side effect of tiagabine is dizziness. Other side effects that have been observed with a rate of statistical significance relative to placebo include asthenia, somnolence, nervousness, memory impairment, tremor, headache, diarrhea, and depression. Adverse effects such as confusion, aphasia, stuttering, and paresthesia (a tingling sensation in the body's extremities, particularly the hands and fingers) may occur at higher dosages of the drug (e.g., over 8 mg/day). Tiagabine has been associated with new-onset seizures and status epilepticus in people without epilepsy in post-marketing surveillance. This may be dose-related, although it has been reported at doses of as low as 4 mg/day, and may also be related to concomitant use of other medications that lower the seizure threshold. Some of these seizures occurred around the time of dose increases. There may be an increased risk of psychosis with tiagabine treatment, although data is mixed and inconclusive. Tiagabine can also reportedly interfere with visual color perception. It has not been found to cause psychomotor, cognitive, or memory impairment. Unlike certain other GABAergic drugs like muscimol, gaboxadol, and CI-966, tiagabine has not been associated with hallucinogenic effects.
== Adverse effects == During the treatment some patients may develop some adverse effects predominantly of the skin and subcutaneous tissue: burning and itching (in absolute the most common side effect), contact dermatitis, dryness and skin irritation.
Congress reconvenes and formally certifies Joe Biden as the next president of the United States on the morning of January 7. President Trump formally concedes to an orderly transition of power to Joe Biden. During the Electoral College vote count, Senator Ted Cruz and Representative Paul Gosar object to Arizona's election results, the first time a vote is forced to accept or reject the objection since 2004. Representative Scott Perry and Senator Josh Hawley subsequently object to Pennsylvania's election results. January 7 Tesla and SpaceX CEO Elon Musk becomes the world's richest person, with a net worth exceeding $185 billion, surpassing Amazon CEO Jeff Bezos. Facebook indefinitely bans President Donald Trump from all of its platforms, citing his role in the January 6 Capitol riot. Twitter permanently suspends Trump's personal account the next day, January 8. Betsy DeVos resigns as Education Secretary in protest of President Trump's role in the January 6 Capitol riot. January 8 Amid an industry crackdown on extremist content following the January 6 Capitol riot, Google removes the mobile app of social networking service Parler from Google Play. Apple suspends the app from its App Store the next day, January 9. Parler goes offline a day later, January 10, when Amazon ceases to provide its cloud computing services. After 36 years, Alex Trebek's final episode of Jeopardy! airs. Ken Jennings becomes the temporary host on January 11 as the search for a new permanent host continues.
Oxidative phosphorylation works by using energy-releasing chemical reactions to drive energy-requiring reactions. The two sets of reactions are said to be coupled. This means one cannot occur without the other. The chain of redox reactions driving the flow of electrons through the electron transport chain, from electron donors such as NADH to electron acceptors such as oxygen and hydrogen (protons), is an exergonic process – it releases energy, whereas the synthesis of ATP is an endergonic process, which requires an input of energy. Both the electron transport chain and the ATP synthase are embedded in a membrane, and energy is transferred from the electron transport chain to the ATP synthase by movements of protons across this membrane, in a process called chemiosmosis. A current of protons is driven from the negative N-side of the membrane to the positive P-side through the proton-pumping enzymes of the electron transport chain. The movement of protons creates an electrochemical gradient across the membrane, which is called the proton-motive force. It has two components: a difference in proton concentration (a H+ gradient, ΔpH) and a difference in electric potential, with the N-side having a negative charge. ATP synthase releases this stored energy by completing the circuit and allowing protons to flow down the electrochemical gradient, back to the N-side of the membrane. The electrochemical gradient drives the rotation of part of the enzyme's structure and couples this motion to the synthesis of ATP.
Sources: en.wikipedia.org
=== D-ribose L-cysteine === D-ribose-L-cysteine (riboceine) is a chemical compound developed as a cysteine prodrug intended to increase endogenous production of glutathione, a naturally occurring intracellular antioxidant. Structurally, it consists of D-ribose, a pentose sugar involved in cellular energy metabolism, chemically bound to L-cysteine, an amino acid required for glutathione biosynthesis.
Later in January, NPR reported that "drug-seizure data suggest that the attacks are doing little to stop the flow of illegal narcotics into the United States." On March 6, 2026, the operation expanded to Ecuador when U.S. forces bombed Comandos de la Frontera as part of the Ecuadorian conflict (2024–present). The campaign was formally named on 13 November 2025 by Pete Hegseth, US secretary of defense, as an expansion of an operation bearing the same name announced by the United States Navy on 28 January 2025. It uses a hybrid fleet of vessels with robotics and autonomous systems to detect and combat alleged drug trafficking networks in the Western Hemisphere. According to an assessment by the Drug Enforcement Administration (DEA), the military strikes against suspected drug-trafficking vessels did not reduce the volume of cocaine entering the United States. Instead, the operations forced criminal organizations to change their smuggling techniques and at the same time eroded traditional law enforcement investigative techniques.
=== Reactivity at carbon (C-3 and C-6) === Regio- and stereocontrolled C-functionalization of 2,5-diketopiperazines at C-3 and C-6 involve enolate, radical and cationic precursors (and N-acyliminium ion) and are sensitive to polar and steric effects.
=== Common === Common side effects include sedation, drooling, constipation, headaches, trembling hands, digestive problems, low blood pressure, dry mouth, nausea, addiction, physical and psychological dependence.
==== Gallic acid biosynthesis ==== Gallic acid is formed from 3-dehydroshikimate by the action of the enzyme shikimate dehydrogenase to produce 3,5-didehydroshikimate. This latter compound spontaneously rearranges to gallic acid.
Sources: en.wikipedia.org
No. Major drug regulators have not approved GW501516 for treating any medical condition. Products sold as cardarine are typically unapproved research chemicals or supplements, so their contents and safety are not assured.
It is prohibited by the World Anti-Doping Agency as a hormone and metabolic modulator. Athletes who test positive for GW501516 can face sanctions, including suspensions and loss of results.
Cardarine is a common or trade-style name, while GW501516 is the research code for the same chemical entity. Some sources also use Endurobol or GSK-516. The names refer to the same compound, not distinct drugs.
LC-MS/MS is common, often after sample cleanup. The assay targets GW501516 or its metabolites.