This is a working overview of nuclear receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-19. Anything still debated is marked as such rather than presented as settled.
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.
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.
Preclinical research reported that GW501516 increased running endurance in mice and improved lipid profiles in some animal species. Early human trials explored effects on high-density lipoprotein cholesterol, triglycerides, and glucose handling, but the program was discontinued. Published human data are sparse and do not establish efficacy for any condition. Studies also examined PPAR delta in cancer biology, with conflicting findings across models. The relationship between receptor activation, tissue context, and disease risk remains an active area of investigation.
Anti-doping laboratories identify GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the usual matrix, and detection can occur after the parent compound has cleared from blood. The exact detection window depends on dose, formulation, individual metabolism, and assay sensitivity. Because the compound is prohibited at all times, athletes are subject to testing in and out of competition. Analytical methods continue to improve as new metabolites and designer analogs are characterized.
GW501516 acts as a ligand for PPAR delta, a nuclear receptor that regulates transcription of genes involved in fatty acid oxidation and energy use. Activation of this receptor in skeletal muscle shifts metabolism toward fat burning in animal models. The compound does not burn fat directly; it changes gene expression over hours to days. Researchers study it to understand metabolic flexibility and exercise adaptation. Effects observed in rodents are not automatically expected in humans.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic PPARδ agonist | Not a steroid or a selective androgen receptor modulator. |
| Common synonyms | Cardarine, GW501516, GW-501516, endurobol | Names vary by supplier and literature source. |
| Appearance | White to off-white powder | Consistent with many small-molecule research chemicals. |
| Solubility | Low in water; soluble in DMSO and ethanol | Often prepared in organic solvent for laboratory work. |
| Primary target | PPARδ (NR1C2) | Nuclear receptor involved in lipid and energy metabolism. |
Cardarine is a common name for GW501516, an investigational compound developed in the 1990s for metabolic conditions. It acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in lipid and energy metabolism. The compound is frequently mislabeled as a selective androgen receptor modulator, or SARM, but its molecular target is different. GW501516 reached early clinical testing before development was discontinued. It has no approved therapeutic use in any country. The name cardarine is not a formal international nonproprietary name.
Regulatory treatment varies, but cardarine is not approved as a medicine. Sports authorities list GW501516 as a prohibited substance, and it is banned at all times under the World Anti-Doping Agency code. Many countries restrict sales for human consumption, while online vendors market it as a research chemical. Such products may lack purity data, and their actual contents can differ from the label. Purchasing or possessing cardarine may carry legal consequences depending on jurisdiction. The compound is not a dietary supplement ingredient in regulated markets.
Clinical development stopped after rodent studies showed tumors at multiple sites. Whether those findings predict human cancer risk remains an open question, but they led sponsors to discontinue programs. Human safety data are limited to small, short-term studies that were not designed to assess cancer risk. Reported effects in those studies included changes in blood lipids, but the evidence is insufficient for medical use. Long-term consequences of nonmedical use are not well characterized. Questions about dose, duration, and individual susceptibility remain unresolved.
Cardarine has no approved therapeutic indication and is not marketed as a medicine. The World Anti-Doping Agency lists GW501516 as a prohibited substance at all times, covering both in-competition and out-of-competition periods. National laws vary: some countries treat it as an unapproved drug subject to import controls, while others have specific restrictions on sale for human consumption. It is often sold as a research chemical, a label that does not imply safety or legality. Enforcement actions have targeted online vendors and shipments.
Anti-doping laboratories identify GW501516 and related metabolites using liquid chromatography coupled with tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be analyzed. The method targets the parent compound and phase I and phase II metabolites, which extend the detection window. Because the substance is prohibited at all times, athletes can be tested outside competition. Detection limits and windows depend on the assay, sample type, and individual metabolism.
Cardarine is frequently described as a fat-burning or endurance-enhancing supplement, but these claims exceed the available evidence. The compound is not a hormone, steroid, or selective androgen receptor modulator. Research articles discuss it as a tool compound for studying PPARδ biology, while anti-doping literature focuses on its abuse and detection. Quality of unapproved products is uncertain, and independent analyses have found impurities or incorrect labeling. Open questions include whether human cancer risk resembles that seen in rodents and how often non-athletes use the substance.
== Contributions in protein structural biology == The three-dimensional structures of various proteins including lactoperoxidase, peptidoglycan recognition protein, lactoferrin from several species, ribosome inactivating proteins, bifunctional inhibitor proteins from plant seeds and various serine proteases and their inhibitors have been determined by his group. The elaborate structural studies of proteins from several important systems as potential drug targets such as phospholipase A2, cyclooxygenase, lipoxygenase, endothelin receptor, endothelin converting enzyme, breast cancer regression proteins and matrix metanosomal proteins as well as their complexes with natural and designed synthetic ligands have been carried out. He had developed the rules of peptide design with alpha, beta – dehydro – amino acids through extensive studies using syntheses, and X-ray and NMR structure determinations. These design rules are being exploited for making specific peptides to act as tight inhibitors of target enzymes and potent antagonists of target receptors for eventually leading to useful therapeutic agents. He initiated a new programme on Clinical Proteomics at the All India Institute of Medical Sciences in which it is intended to characterize all the proteins that are expressed during various patho/physiological conditions. The newly identified proteins will either be useful as biomarkers or they may be associated with the progression of diseases making them important targets for drug design.
=== Pheochromocytoma === Metirosine is primarily used to reduce these symptoms in patients with pheochromocytoma. It is contraindicated for the treatment of essential hypertension. Pheochromocytoma is a rare neuroendocrine tumor that results in the release of too much epinephrine and norepinephrine, hormones that control heart rate, metabolism, and blood pressure. AMPT was used in the 1960s for preoperative pharmacological control of catecholamine overexpression that causes hypertension and other arterial and cardiac abnormalities. The use of AMPT to treat Pheochromocytoma prior to surgery was discontinued due to its extensive side effects.
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In pharmacokinetics, bioavailability generally refers to the fraction of a drug that is absorbed systemically and is thus available to produce a biological effect. This is often measured by quantifying the "AUC". In order to determine the respective AUCs, the serum concentration vs. time plots are typically gathered using C-14 labelled drugs and AMS (accelerated mass spectrometry). Bioavailability can be measured in terms of "absolute bioavailability" or "relative bioavailability". Absolute bioavailability refers to the bioavailability of a drug when administered via an extravascular dosage form (i.e. oral tablet, suppository, subcutaneous, etc.) compared with the bioavailability of the same drug administered intravenously (IV). This is done by comparing the AUC of the non-intravenous dosage form with the AUC for the drug administered intravenously. This fraction is normalized by multiplying by each dosage form's respective dose. F abs = ( AUC non-IV AUC IV ) × ( Dose IV Dose non-IV )
Sources: en.wikipedia.org
== Side effects == Research indicates that cannabidiol may reduce adverse effects of THC, particularly those causing intoxication and sedation, but only at high doses. Safety studies of cannabidiol showed it is well tolerated, but may cause fatigue, somnolence, sedation, diarrhea, or changes in appetite as common adverse effects, with the most common being somnolence and sedation. Side effects of CBD are dose related. Epidiolex documentation lists sleepiness, insomnia and poor quality sleep, decreased appetite, diarrhea, and fatigue. In November 2019, the US Food and Drug Administration (FDA) issued concerns about the safety of cannabidiol, stating that CBD use has potential to cause hepatotoxicity, interfere with the mechanisms of prescription drugs, produce gastrointestinal disorders, or affect alertness and mood. In 2020–2023, the FDA updated its safety concerns about CBD, acknowledging the unknown effects of protracted use, how it affects the developing brain, fetus, or infants during breastfeeding, whether it interacts with dietary supplements or prescription drugs, whether male fertility is affected, and its possible side effects, such as drowsiness. As of September 2019, 1,085 people contacted US poison control centers about CBD-induced illnesses, doubling the number of cases over the 2018 rate and increasing by nine times the case numbers of 2017. Of cases reported in 2019, more than 33% received medical attention and 46 people were admitted to a hospital intensive care unit, possibly due to exposure to other products, or drug interactions with CBD.
== Career == Vasquez began his career as the business editor for the Las Cruces Bulletin from 2008 to 2011. He later served as executive director of the Las Cruces Hispanic Chamber of Commerce before joining SDS Inc. as executive vice president for public relations. From 2013 to 2015, Vasquez worked as a field representative for U.S. Senator Martin Heinrich. He also worked as vice president of communications for First Focus on Children, director of community relations for the New Mexico Wildlife Federation, and deputy state director for the Wilderness Society. He later worked as deputy director for federal lands at the Western Conservation Foundation from 2019 to 2021. In 2017, Vasquez was elected to the Las Cruces City Council, where he served until 2021.
== Structure == Glutamine can exist in either of two enantiomeric forms, L-glutamine and D-glutamine. The L-form is found in nature. Glutamine contains an α-amino group which is in the protonated −NH3+ form under biological conditions and a carboxylic acid group which is in the deprotonated −COO− form, known as carboxylate, under physiological conditions.
Sources: en.wikipedia.org
Cardarine is a common name for GW501516, a synthetic PPARδ agonist. It is not a steroid or a selective androgen receptor modulator. It was developed and studied as a research compound for metabolic pathways.
It binds to and activates PPARδ, a nuclear receptor that regulates genes related to fatty acid oxidation and energy use. This activation alters transcription in tissues such as skeletal muscle and liver. The full range of downstream effects in humans is not fully established.
No, cardarine is not known to occur naturally in plants, animals, or humans. It is a synthetic molecule produced for laboratory research. Products labeled as cardarine should therefore be treated as manufactured chemicals with variable purity.
It binds to and activates PPAR delta, a nuclear receptor that controls expression of genes related to fatty acid oxidation. This mechanism can alter energy metabolism in animal models. It is not a direct stimulant or fat-burning enzyme.