A practical reference on nuclear receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-15 and is reviewed periodically as new material appears.
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.
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.
Legal status varies by country. In some places, cardarine is controlled under medicines or psychoactive substances laws; in others, it may be sold with minimal oversight as a research chemical. Customs agencies have intercepted shipments, and several national health agencies have issued warnings about products marketed for bodybuilding or performance enhancement. The lack of a standardized pharmaceutical supply means identity, purity, and contamination levels can differ widely between samples. These factors make cardarine a regulatory and public health concern rather than a conventional prescription drug.
| 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 a common name for GW501516, a synthetic compound developed in the 1990s through research collaborations involving GlaxoSmithKline. It belongs to a class of molecules known as peroxisome proliferator-activated receptor delta agonists. Early studies explored its effects on lipid metabolism and energy expenditure in animal models. The compound was never approved as a human medicine, and clinical development was discontinued. In the years since, it has appeared in fitness and bodybuilding communities as a performance-enhancing substance. Regulatory agencies classify it as an unapproved drug.
PPARδ is a nuclear receptor that regulates gene expression related to fatty acid oxidation, glucose homeostasis, and mitochondrial function. GW501516 binds to this receptor with high affinity and activates downstream signaling in skeletal muscle and other tissues. Animal studies reported increased endurance and altered fuel preference, but human data remain limited and inconsistent. The precise relationship between receptor activation and observed physiological changes is still an area of active investigation. Researchers have also examined whether the compound affects inflammation or cell proliferation. No approved therapeutic indication exists for cardarine.
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.
Detection of GW501516 in biological samples generally relies on liquid chromatography coupled with tandem mass spectrometry. Urine is a common matrix in anti-doping analysis, while blood or plasma may be used in research settings. Sample preparation can involve enzymatic hydrolysis, protein precipitation, or solid-phase extraction before instrumental analysis. Because the compound undergoes metabolism, assays may target the parent molecule, one or more metabolites, or both. Detection windows are not fixed; they depend on factors such as dose, route, individual metabolism, and assay sensitivity. Reference standards are required for accurate identification and quantification.
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.
== Mechanism of action == Cefuroxime axetil is a second generation cephalosporin that, like penicillins antibiotics, contains a β-lactam ring structure. Cephalosporins work as bactericidal antibiotics; that by binding to penicillin-binding proteins (PBPs), inhibit the last step of the bacterial cell wall synthesis. Once the β-lactam ring binds to PBPs, cross-linking between peptidoglycan units is inhibited.
=== Cricket === January New Zealand completes 2–1 series win over Sri Lanka in a three-match Twenty20 International series in New Zealand. New Zealand defeats Sri Lanka 2–1 in a three-match ODI series in New Zealand. December 19 December – Following a prolonged disagreement with New Zealand Cricket's board and key cricket stakeholders, Scott Weenink resigned from his position as its chief executive.
== Science and technology == Caldwell 18 (NGC 185), a dwarf spheroidal galaxy of the Local Group in the constellation Cassiopeia Carbon-18 (C-18 or 18C), an isotope of carbon C18, the molecular formula of cyclo(18)carbon C18, an octadecyl-type hydrocarbon with 18 carbon atoms, such as Fatty acids such as Stearic acid, C18H36O2 Oleic acid C18H34O2 C18 bonded silica stationary phase column, a type of reversed-phase chromatography column IEC 60320 C18, a power connector Colorectal cancer (ICD-10 code) ISO/IEC 9899:2018 standard for the programming language C, informally named C18
Sources: en.wikipedia.org
=== Legal status === In January 2016, Eli Lilly submitted a new drug application to the US Food and Drug Administration (FDA) for the approval of baricitinib to treat moderately-to-severely active rheumatoid arthritis. In December 2016, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) recommended the approval of baricitinib as a therapy for rheumatoid arthritis. European Union approval was granted in February 2017. Despite widespread expectations that the FDA would approve baricitinib for rheumatoid arthritis, in April 2017, the FDA issued a rejection, citing concerns about dosing and safety. In May 2018, baricitinib was approved in the United States for the treatment of rheumatoid arthritis. In March 2020, the US FDA granted breakthrough therapy designation to baricitinib for the treatment of alopecia areata and granted approval in June 2022. The efficacy and safety of baricitinib in alopecia areata was studied in two randomized, double-blind, placebo-controlled trials (Trial AA-1 and Trial AA-2) with participants who had at least 50% scalp hair loss as measured by the Severity of Alopecia Tool (SALT) for more than six months. Participants in these trials received either a placebo, 2 milligrams of baricitinib, or 4 milligrams of baricitinib every day. The primary measurement of efficacy for both trials was the proportion of participants who achieved at least 80% scalp hair coverage at week 36.
=== Legal status === Suvorexant is a schedule IV controlled substance under the Controlled Substances Act in the United States. It is not a controlled drug in Australia, instead being classed as a prescription-only medicine (Schedule 4 (S4)) in this country.
In Japan, the Mister Donut franchise is owned by Duskin Co., Ltd., a part of the Mitsui conglomerate. Mister Donut is the largest donut franchise chain in Japan, with a total of 961 retail shops operating as of March 2021. Keiji Chiba, who was Duskin Company's general manager and director of food industries, adjusted the recipes and gave a higher class image so the company would be successful in the Japanese market. Before the introduction of Mister Donut, the Japanese perceived doughnuts as being snacks for children. The Star wrote in 2007 that "Mister Donut has gained a following among mostly younger Japanese for its American-style doughnuts, decor and music, becoming the country's biggest donut chain." On September 13, 2013, a survey by the Japanese retail research company, Softbrain Field, surveyed close to 6000 Japanese citizens of all ages on their favorite fast food restaurant. Mister Donut came in third, at 17%, behind McDonald's at 33% and MOS Burger at 25%.
Sources: en.wikipedia.org
Antidotes are agents that can neutralise the effects of a poison or toxin. Antidotes counteract the effects of toxins in many ways, such as by blocking the absorption of the toxin, binding and neutralising the poison, opposing the toxin's end-organ function, or blocking the toxin's conversion to more hazardous metabolites. In addition to lowering the amount of free or active poison present, antidote delivery may also lessen the toxin's effects on organs through competitive inhibition, receptor blockage, or direct antagonistic interaction. The therapeutic index or ratio (TD50/ED50), which is the ratio of the toxic dosage (TD) or fatal dose (LD) to the effective dose (ED), determines the level of safety associated with a substance.
=== Chemical properties === Technetium is located in group 7 of the periodic table, between rhenium and manganese. As predicted by the periodic law, its chemical properties are between those two elements. Of the two, technetium more closely resembles rhenium, particularly in its chemical inertness and tendency to form covalent bonds. This is consistent with the tendency of period 5 elements to resemble their counterparts in period 6 more than period 4 due to the lanthanide contraction. Unlike manganese, technetium does not readily form cations (ions with net positive charge). Technetium exhibits nine oxidation states from −1 to +7, with +4, +5, and +7 being the most common. Technetium dissolves in aqua regia, nitric acid, and concentrated sulfuric acid, but not in hydrochloric acid of any concentration. Metallic technetium slowly tarnishes in moist air and, in powder form, burns in oxygen. When reacting with hydrogen at high pressure, it forms the non-stoichiometric hydride TcH1.3 and while reacting with carbon it forms Tc6C, with cell parameter 0.398 nm. Technetium can catalyse the destruction of hydrazine by nitric acid, and this property is due to its multiplicity of valencies. This caused a problem in the separation of plutonium from uranium in nuclear fuel processing, where hydrazine is used as a protective reductant to keep plutonium in the trivalent rather than the more stable tetravalent state. The problem was exacerbated by the mutually enhanced solvent extraction of technetium and zirconium at the previous stage, and required a process modification.
All patients were switched to or continued their treatments only with gemigliptin 50 mg qd during the extension period. A further decrease in HbA1c was observed in the continued treatment with gemigliptin 50 mg in this extension period, and the mean change from baseline at 52 weeks (–0.87%) was still clinically and statistically significant (full analysis set analysis, P<0.0001). In another blinded, active-controlled, phase III trial (study identifier: LG-DPCL011), eligible patients with HbA1c greater than 7.5% were randomized to receive gemigliptin 50 mg qd with metformin slow release (SR) qd (n=141), gemigliptin 50 mg qd (n=142), or metformin SR qd (n=150) for 24 weeks. After 24 weeks, the reduction from the baseline in HbA1c was –1.24% for gemigliptin monotherapy. In a meta-analysis involving data from 10 randomized controlled trials (1,792 patients), Dutta et al. demonstrated the good glycaemic efficacy, durability and safety of gemigliptin in managing type-2 diabetes Initial combination therapy with metformin In this randomized, blinded, active-controlled, phase III trial (study identifier: LG-DPCL011, INICOM study; ClinicalTrials.gov registration number: NCT01787396), eligible patients with an HbA1c greater than 7.5% were randomized to gemigliptin 50 mg qd+metformin SR qd (n=141), gemigliptin 50 mg qd (n=142), or metformin SR qd (n=150). From weeks 2 to 6, metformin SR was uptitrated incrementally from 500 to 2,000 mg/day maximum in the gemigliptin/metformin and metformin groups.
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.
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.