A practical reference on Mass spectrometry: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-12-16. Anything still debated is marked as such rather than presented as settled.
Cardarine is a synthetic compound also known as GW501516, GW-501516, and sometimes endurobol. It was developed as a selective agonist of peroxisome proliferator-activated receptor delta, a nuclear receptor involved in fatty acid oxidation and energy metabolism. The compound was studied in preclinical models for metabolic and cardiovascular conditions, but it did not become a marketed human medicine. In regulatory and anti-doping contexts, it is treated as a prohibited substance rather than a licensed medicine.
The pharmacological interest in cardarine centers on PPARδ activation and its downstream effects on lipid handling and mitochondrial function. In animal studies, PPARδ agonists have been associated with changes in exercise endurance and fatty acid utilization, though results vary by model and protocol. Human data remain sparse, and the absence of large controlled trials limits conclusions about efficacy. Researchers often describe the compound as a tool for probing PPARδ biology rather than a proven therapeutic agent.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | GW501516, GW-501516, GW 501516, endurobol | Names vary in research and anti-doping documents. |
| Chemical class | Synthetic PPARδ agonist | Small-molecule nuclear receptor ligand. |
| CAS Registry Number | 317318-70-0 | Identifier commonly associated with GW501516. |
| Appearance | White to off-white powder | Typical for purified research material. |
| Solubility | Low in water; soluble in DMSO and ethanol | Organic solvents are common for laboratory stock solutions. |
Laboratory handling focuses on identity, purity, and stability. Reference standards are typically stored cold and dry, protected from light, because solutions can degrade over time. Analytical checks may use high-performance liquid chromatography with ultraviolet detection or mass spectrometry. Impurities and related substances can be separated chromatographically and compared with a known standard. Because cardarine is not an approved drug, compendial monographs are absent, and laboratories often rely on in-house methods. Reported purity varies among unregulated products and should not be assumed from a label.
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.
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.
The Jackson Labs DO (Diversity Outbred) project is a mouse breeding program using multiple inbred founder strains to create a genetically diverse population of mice for use in scientific research. These mice are designed for fine genetic mapping, and capture a large portion of the genetic diversity of the mouse genome. This project has resulted in over 1,000 genetically diverse mice which have been used to identify genetic factors for diseases such as obesity, cancer, diabetes, and alcohol use disorder.
When the USSR was dissolved in 1991, Moscow remained the capital of the Russian Federation. Since then, a market economy has emerged, producing a significant increase in Western-style retailing, services, architecture, and lifestyles. The city continued to grow during the 1990s and 2000s, its population rising from less than nine million to more than ten million. Scholars Mason and Nigmatullina argue that Soviet-era urban-growth controls produced controlled and sustainable metropolitan development, typified by the greenbelt built in 1935. Since then, however, low-density suburban sprawl has increased significantly, as a result of heavy demand for single-family dwellings (rather than multi-family apartments). In 1995–1997, the MKAD ring road was widened from an initial four lanes to ten lanes. In December 2002, Bulvar Dmitriya Donskogo became the first Moscow Metro station to open outside the MKAD. The Third Ring Road—intermediate between the early 19th-century Garden Ring and the Soviet-era outer ring road—was completed in 2004. The greenbelt is becoming more fragmented, and satellite cities are appearing at the fringe. Summer dachas are being converted into year-round residences; with the proliferation of automobiles, the city has heavy traffic congestion. Multiple old churches and other examples of architectural heritage that were demolished during the Stalin era have been restored, such as the Cathedral of Christ the Saviour. In the 2010s, Moscow's administration launched long-term projects such as the Moja Ulitsa (lit.
Antioxidants may be added to industrial products, such as stabilizers in fuels and additives in lubricants, to extend their usable lifetimes by preventing oxidation and polymerization that leads to the formation of engine-fouling residues.
=== Animal-derived === Some drugs used in modern medicine have been discovered in animals or are based on compounds found in animals. For example, the anticoagulant drugs, hirudin and its synthetic congener, bivalirudin, are based on saliva chemistry of the leech, Hirudo medicinalis. Used to treat type 2 diabetes, exenatide was developed from saliva compounds of the Gila monster, a venomous lizard.
Sources: en.wikipedia.org
Target-mediated drug disposition (TMDD) is the process in which a drug binds with high affinity to its pharmacological target (for example, a receptor) to such an extent that affects its pharmacokinetic characteristics. Various drug classes can exhibit TMDD, most often these are large compounds (biologics such as antibodies, cytokines or growth factors) but also smaller compounds can exhibit TMDD (such as warfarin and CHK-336). A typical TMDD pattern of antibodies displays non-linear clearance and can be seen at concentration ranges that are usually defined as 'mid-to-low'. In this concentration range, the target is partly saturated.
From 1980 to 2008, the prevalence of obesity in children aged 6 to 11 years tripled from 6.5% to 19.6%. The prevalence of obesity in teenagers more than tripled from 5% to 18.1% in the same time frame. In less than one generation, the average weight of a child has risen by 5 kg in the United States. The CDC has reported that, in 2014, 17.2% of youth aged 2–19 were considered obese and another 16.2% were overweight. Meaning, over one-third of children and teens in the US were overweight or obese. Statistics from a 2016–2017 page on the CDC's official website that 13.9% of toddlers and children age 2–5, 18.4% of children 6–11, and 20.6% of adolescents 12–19 are obese. The prevalence of child obesity in today's society concerns health professionals because a number of these children develop health issues that weren't usually seen until adulthood. Some of the consequences in childhood and adolescent obesity are psychosocial. Overweight children and overweight adolescents are targeted for social discrimination, and thus, they begin to stress-eat. The psychological stress that a child or adolescent can endure from social stigma can cause low self-esteem which can hinder a child's after school social and athletic capability, especially in plump teenage girls, and could continue into adulthood.
==== The labile iron pool ==== In the cytoplasm, ferrous iron is found in a soluble, chelatable state which constitutes the labile iron pool (~0.001 mM). In this pool, iron is thought to be bound to low-mass compounds such as peptides, carboxylates and phosphates, although some might be in a free, hydrated form (aqua ions). Alternatively, iron ions might be bound to specialized proteins known as metallochaperones. Specifically, poly-r(C)-binding proteins PCBP1 and PCBP2 appear to mediate transfer of free iron to ferritin (for storage) and non-heme iron enzymes (for use in catalysis). The labile iron pool is potentially toxic due to iron's ability to generate reactive oxygen species. Iron from this pool can be taken up by mitochondria via mitoferrin to synthesize Fe-S clusters and heme groups.
=== Home oximetry and peripheral arterial tone measurement === Home oximetry (a non-invasive method of monitoring blood oxygenation) used in concert with Peripheral Arterial Tone (PAT) technology has been approved by the FDA at-home sleep apnea diagnosis since November 2001 when Itamar Medical obtained 510(k) clearance for the Watchpat-100. Although PAT-based at-home sleep tests are not considered as accurate as polysomnography-based tests, their AHI or AHI-equivalent measurements are considered sufficient for coverage purposes in the United States by Medicare and private health insurance companies.
== Overdose == LGD-4033 has been assessed in clinical trials at single doses ranging from 0.1 to 22 mg and at repeated doses ranging from 0.1 to 2 mg/day for 3 to 12 weeks. The drug sold via black-market Internet suppliers and used non-medically is often taken at much higher doses than those used in repeated-dose clinical trials (e.g., 5–10 mg/day), with unknown adverse effects and risks.
Sources: en.wikipedia.org
Cardarine is an investigational synthetic compound that acts as a PPARδ agonist. It is also known as GW501516 and has been studied mainly in preclinical research. It is not an approved medicine.
No. Cardarine is not a steroid hormone; it targets the nuclear receptor PPARδ. Its classification in anti-doping rules differs from anabolic steroids, though it remains prohibited in sport.
Early rodent studies reported tumor formation at multiple sites, which raised safety concerns. Sponsors stopped clinical development, and no approved human product exists.
LC-MS/MS is common, often after sample cleanup. The assay targets GW501516 or its metabolites.