This is a working overview of LC-MS/MS, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.
GW501516 acts as an agonist at the peroxisome proliferator-activated receptor delta, a nuclear receptor that regulates gene expression. Activation shifts transcription toward genes involved in fatty acid uptake, oxidation, and energy expenditure. The compound does not bind the androgen receptor and therefore differs from anabolic steroids and SARMs. In rodent models, this metabolic shift has been linked to increased running endurance and reduced fat accumulation. The exact downstream pathways in humans remain incompletely characterized.
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.
| Property | Value | Notes |
|---|---|---|
| Primary target | PPARδ | Nuclear receptor; not androgen receptor |
| Studied indications | Dyslipidemia; obesity; diabetes | Early clinical research; development discontinued |
| Rodent toxicity | Tumor formation in multiple tissues | Dose-dependent findings in some studies |
| Human approval | None | No approved therapeutic use |
| Typical analytical method | LC-MS/MS | Used for identity and quantification |
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.
Cardarine is not approved for human therapeutic use in any major jurisdiction. It appears on the World Anti-Doping Agency Prohibited List as a PPARδ agonist within the hormone and metabolic modulators category. Sports organizations test for it because it has been detected in athlete samples and seized products. Regulatory actions against marketed research chemical versions have occurred in several countries, though enforcement varies. Availability through unregulated channels complicates oversight.
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.
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.
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.
GW501516 acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in transcription of genes related to lipid handling and energy use. Activation of PPARδ can shift skeletal muscle toward greater fatty acid oxidation in animal models, which is one reason it drew interest for metabolic disease and exercise research. The exact downstream effects depend on tissue, species, dose, and duration. Human data are sparse, so many proposed benefits remain hypotheses rather than established clinical outcomes.
Laboratory studies have examined GW501516 in cell cultures and rodents for conditions such as dyslipidemia, insulin resistance, and obesity. Some trials in humans were initiated, but development was discontinued after preclinical findings raised concerns about cancer in certain models. Those findings do not prove that the compound causes cancer in people, but they contributed to regulatory caution. Later reviews often describe the evidence as preliminary and insufficient for assessing long-term safety.
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.
Safety discussions about cardarine frequently cite rodent carcinogenicity findings reported in the 2000s. In those studies, treated animals developed tumors at multiple sites, leading sponsors to discontinue clinical development. The relevance of these findings to humans has not been resolved, but they are a major reason the compound is not approved. Current literature emphasizes uncertainty about long-term effects and the risks of unregulated use. Regulators and health agencies have not established a safe human exposure level.
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.
== Cannabinoid receptors == Cannabinoid receptor 1 (CBR1) and Cannabinoid receptor 2 (CBR2) are the two main binding targets in the endocannabinoid system. They share similar molecular shape and signalling mechanisms, but differ in their tissue distribution and effects. CB1R mainly presents in the central nervous system, with its activation commonly associated with the regulation of mood, pain and appetite. CB2R is abundant in the immune tissues, for example spleen, lymph nodes and bone marrow. Its activation causes immunosuppressive effects.
=== Netball === 10 September - Netball New Zealand suspends the Silver Ferns' coach Dame Noeline Taurua over concerns over her management style and bullying allegations. 25 October – Following an internal investigation and protracted negotiations, Netball New Zealand reinstates Dame Taurua as the Silver Ferns' coach, effective late 2025.
Resting membrane potential The baseline electrical potential across the neuron's membrane when it is not actively sending signals, typically around –70 mV in neurons. Reticular formation A network of nuclei in the brainstem involved in regulating arousal, attention, sleep–wake cycles, and autonomic functions. Retina A thin layer of tissue at the back of the eye that contains photoreceptors and neurons responsible for detecting light and initiating visual processing. Retinotopy An orderly representation of the visual field maintained throughout the visual pathways, including the visual cortex. Retrograde amnesia A type of memory loss where individuals cannot recall past memories prior to a brain injury, while the ability to form new memories may be preserved. Retrograde transport The movement of materials from the axon terminal back to the cell body, typically via dynein motors. Used for recycling vesicles and transporting signals. Rett syndrome A rare neurodevelopmental disorder, primarily affecting females, caused by mutations in the MECP2 gene. Characterized by developmental regression, motor problems, and seizures. Reuptake The process by which neurotransmitters are reabsorbed by the presynaptic neuron after being released, terminating synaptic transmission. Reward system A group of brain structures involved in motivation, pleasure, and reinforcement. Includes the ventral tegmental area, nucleus accumbens, and prefrontal cortex. Rhinal cortex A region of the medial temporal lobe that plays a key role in memory and object recognition.
=== United States of America === In the US, home sleep testing is increasingly being preferred by private insurance carriers. For individuals who have high co-pays or deductibles, a home sleep test can be done for a fraction of the cost of polysomnography. Radiofrequency ablation was recognized by the American Academy of Otolaryngology as a somnoplasty treatment option in selected situations for mild to moderate OSA, but the evidence was judged insufficient for routine adoption by the American College of Physicians.
Additional types of nevi do not involve disorders of pigmentation or melanocytes. These additional nevi represent hamartomatous proliferations of the epithelium, connective tissue, and vascular malformations.
Sources: en.wikipedia.org
==== Maintenance phase ==== After the 5–7 day loading phase, muscle creatine stores are fully saturated and supplementation only needs to cover the amount of creatine broken down per day. This maintenance dose was originally reported to be around 2–3 g/day (or 0.03 g/kg/day), however, some studies have suggested 3–5 g/day maintenance dose to maintain saturated muscle creatine.
=== German Empresses (1871–1918) === Augusta of Saxe-Weimar-Eisenach (1811–1890), consort of Emperor William I (tenure 1871–1888) Victoria, Princess Royal (1840–1901), consort of Emperor Frederick III (tenure 1888) Augusta Victoria of Schleswig-Holstein (1858–1921), first consort of Emperor William II (tenure 1888–1918)
Sulfur forms several polyatomic molecules. The best-known allotrope is octasulfur, cyclo-S8. The point group of cyclo-S8 is D4d and its dipole moment is 0 D. Octasulfur is a soft, bright-yellow solid that is odorless. It melts at 115.21 °C (239.38 °F), and boils at 444.6 °C (832.3 °F). At 95.2 °C (203.4 °F), below its melting temperature, cyclo-octasulfur begins slowly changing from α-octasulfur to the β-polymorph. The structure of the S8 ring is virtually unchanged by this phase transition, which affects the intermolecular interactions. Cooling molten sulfur freezes at 119.6 °C (247.3 °F), as it predominantly consists of the β-S8 molecules. Between its melting and boiling temperatures, octasulfur changes its allotrope again, turning from β-octasulfur to γ-sulfur, again accompanied by a lower density but increased viscosity due to the formation of polymers. At higher temperatures, the viscosity decreases as depolymerization occurs. Molten sulfur assumes a dark red color above 200 °C (392 °F). The density of sulfur is about 2 g/cm3, depending on the allotrope; all of the stable allotropes are excellent electrical insulators. The sublimation of sulfur becomes noticeable more or less between 20 °C (68 °F) and 50 °C (122 °F), and occurs readily in boiling water at 100 °C (212 °F). Sulfur is insoluble in water but soluble in carbon disulfide and, to a lesser extent, in other nonpolar organic solvents, such as benzene and toluene. Sulfur is also soluble in supercritical carbon dioxide.
ω (omega) is the angle in the chain Cα − C' − N − Cα, φ (phi) is the angle in the chain C' − N − Cα − C' ψ (psi) is the angle in the chain N − Cα − C' − N (called φ′ by Ramachandran) The figure at right illustrates the location of each of these angles (but it does not show correctly the way they are defined). The planarity of the peptide bond usually restricts ω to be 180° (the typical trans case) or 0° (the rare cis case). The distance between the Cα atoms in the trans and cis isomers is approximately 3.8 and 2.9 Å, respectively. The vast majority of the peptide bonds in proteins are trans, though the peptide bond to the nitrogen of proline has an increased prevalence of cis compared to other amino-acid pairs. The side chain dihedral angles are designated with χn (chi-n). They tend to cluster near 180°, 60°, and −60°, which are called the trans, gauche−, and gauche+ conformations. The stability of certain sidechain dihedral angles is affected by the values φ and ψ. For instance, there are direct steric interactions between the Cγ of the side chain in the gauche+ rotamer and the backbone nitrogen of the next residue when ψ is near −60°. This is evident from statistical distributions in backbone-dependent rotamer libraries. Dihedral angles have also been defined by the IUPAC for other molecules, such as the nucleic acids (DNA and RNA) and for polysaccharides.
== Structure == Antithrombin is also termed antithrombin III (AT III). The designations antithrombin I through to antithrombin IV originate in early studies carried out in the 1950s by Seegers, Johnson and Fell.
Sources: en.wikipedia.org
It targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not act primarily on androgen receptors. This distinction separates it from SARMs.
Rodent studies found dose-dependent tumors in several organs. The sponsor discontinued the program over cancer concerns. Human risk from long-term use remains unknown.
Controlled human endurance trials are lacking. Animal studies show increased exercise capacity under some conditions. Anecdotal reports are not equivalent to clinical evidence.
Cardarine is commonly known as GW501516 or GW-1516. These names refer to the same synthetic compound. It is not a brand-name approved medicine.