A practical reference on fatty acid oxidation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-27. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Common name | Cardarine | Also called GW501516 and endurobol. |
| Chemical formula | C21H18F3NO3S2 | Molecular weight about 453.5 g/mol. |
| Appearance | White to off-white solid | Form depends on synthesis and purity. |
| Solubility | Soluble in DMSO and ethanol | Low solubility in water. |
| Typical storage | -20 °C, desiccated, protected from light | Common for research chemicals. |
Safety concerns emerged from long-term animal studies. In rodents given the compound for extended periods, researchers found an increased incidence of certain cancers, including liver and bladder tumors. These findings contributed to the discontinuation of clinical development. Whether similar risks apply to short-term or low-level exposure in humans is not established, and controlled human safety data are limited. The relevance of high-dose rodent carcinogenicity findings to human use remains a subject of debate.
Human trials of GW501516 were small and short in duration. They examined lipid levels, glucose handling, and other metabolic markers, but the programs were halted after the animal cancer findings. No approved therapeutic product exists, and published human data are insufficient for establishing long-term safety. Reports of use for athletic performance come mainly from non-clinical settings and cannot be verified through controlled trials. Independent testing of products sold as cardarine has found inconsistent purity and labeling.
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.
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.
== Chemistry == Metformin hydrochloride (1,1-dimethylbiguanide hydrochloride) is freely soluble in water, slightly soluble in ethanol, but almost insoluble in acetone, ether, or chloroform. The pKa of metformin is 12.4. The usual synthesis of metformin, originally described in 1922, involves the one-pot reaction of a heated solution of dimethylamine hydrochloride and 2-cyanoguanidine.
Nicotine is classified as a poison, and it is "extremely hazardous". The CDC says it is "toxic to developing fetuses and is a health danger for pregnant women." It can harm brain development up to age twenty-five, and early use of nicotine can predispose young people to smoking and drug use. However, at doses typically used by consumers, it presents little if any hazard to adult users. Although at low amounts nicotine has a mild analgesic effect, at sufficiently high doses nicotine may result in nausea, vomiting, diarrhea, salivation, bradycardia, and possibly seizures, hypoventilation, and death.
== Medical uses == The two most commonly used methods of confirming allergen sensitization are skin testing and allergy blood testing. Both methods are recommended by the NIH guidelines and have similar diagnostic value in terms of sensitivity and specificity. Advantages of the allergy blood test range from: excellent reproducibility across the full measuring range of the calibration curve, it has very high specificity as it binds to allergen specific IgE, and extremely sensitive too, when compared with skin prick testing. In general, this method of blood testing (in-vitro, out of body) vs skin-prick testing (in-vivo, in body) has a major advantage: it is not always necessary to remove the patient from an antihistamine medication regimen, and if the skin conditions (such as eczema) are so widespread that allergy skin testing cannot be done. Allergy blood tests, such as ImmunoCAP, are performed without procedure variations, and the results are of excellent standardization. Adults and children of any age can take an allergy blood test. For babies and very young children, a single needle stick for allergy blood testing is often more gentle than several skin tests. However, skin testing techniques have improved. Most skin testing does not involve needles and typically skin testing results in minimal patient discomfort. Drawbacks to RAST and ImmunoCAP techniques do exist. Compared to skin testing, ImmunoCAP and other RAST techniques take longer to perform and are less cost effective.
Sources: en.wikipedia.org
Hemoglobin (haemoglobin, Hb or Hgb) is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobin in the blood carries oxygen from the respiratory organs (lungs or gills) to the other tissues of the body, where it releases the oxygen to enable aerobic respiration which powers an animal's metabolism. A healthy human has 12 to 20 grams of hemoglobin in every 100 mL of blood. Hemoglobin is a metalloprotein, a chromoprotein, and a globulin. In mammals, hemoglobin makes up about 96% of a red blood cell's dry weight (excluding water), and around 35% of the total weight (including water). Hemoglobin has an oxygen-binding capacity of 1.34 mL of O2 per gram, which increases the total blood oxygen capacity seventy-fold compared to dissolved oxygen in blood plasma alone. The mammalian hemoglobin molecule can bind and transport up to four oxygen molecules. Hemoglobin also transports other gases. It carries off some of the body's respiratory carbon dioxide (about 20–25% of the total) as carbaminohemoglobin, in which CO2 binds to the heme protein. The molecule also carries the important regulatory molecule nitric oxide bound to a thiol group in the globin protein, releasing it at the same time as oxygen.
Hardee's was purchased by Canadian company Imasco Limited in 1981. In 1982, General Foods sold Burger Chef to Imasco for $44 million. Imasco converted many locations to Hardee's restaurants and let franchises and locations near existing Hardee's locations convert to other brands. Remaining restaurants that did not convert to Hardee's or new names and branding simply closed. A new management team, in the early 1980s, seeking to cut costs, changed the signature burger recipe and eliminated the flagship menu item, the Big Twin. The Big Deluxe continued to be offered throughout the 1990s. For a few years after acquiring the Roy Rogers Restaurants fast food chain in the early 1990s, Hardee's outlets sold fried chicken prepared using the popular Roy Rogers Restaurant recipe hoping it could compete with KFC. In addition to Roy Rogers, Hardee's also owned Rax Roast Beef for a period of time and sold roast beef sandwiches throughout the Hardee's system.
== Service == Mrksich has also been active in serving the scientific community in a number of roles. These include his current service as the Scientific Director of the Searle Scholars Program, as a member of the Board of Governors for Argonne National Laboratory, and as a member of the Board of Directors for the Camille & Henry Dreyfus Foundation. His past appointments include service and chairing DARPA’s Defense Sciences Research Council and many program advisory committees.
These positions were eventually quashed by two important advancements that happened later in the 19th century: the development of the periodic table and the discovery that molecules have an internal architecture that determines their properties.
Sources: en.wikipedia.org
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.
It activates PPARδ, a nuclear receptor that influences gene expression related to lipid and energy metabolism. Animal studies show changes in endurance and lipid levels. Human effects and risks are not well established.
No, cardarine is not a steroid. It belongs to a different chemical class, the PPARδ agonists. It is also not a selective androgen receptor modulator.
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.