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Background And Regulatory History — Worked Examples

By Editorial Desk · published 2025-07-01 · last reviewed 2025-07-17 · Data

The short version of Investigational drug fits in a sentence. The long version — which is the one that helps — is below.

This page was last updated on 2025-07-17 and is reviewed periodically as new material appears.

Background and Regulatory History

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.

Mechanism and Safety Research

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.

Early clinical research explored GW501516 for lipid disorders, obesity, and diabetes. Some short-term human studies reported changes in HDL cholesterol, LDL cholesterol, and triglycerides. The development program was discontinued after rodent studies showed dose-dependent tumor formation in multiple tissues, including liver, bladder, stomach, and skin. These findings raised concerns about long-term cancer risk in humans. Because human exposure data are limited, the clinical significance of the rodent tumors remains uncertain.

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.

Cardarine at a glance

PropertyValueNotes
Common nameCardarineCommon internet and media name.
Research codeGW501516Also written GW-1516.
Drug classPPARδ agonistNot a selective androgen receptor modulator.
Development statusDiscontinuedClinical development halted after rodent cancer findings.
Regulatory statusProhibited in sportListed by WADA; not approved as medicine.

Mechanism and Laboratory Detection

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.

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Identity and Regulatory Status

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.

Regulation and Analytical Detection

Cardarine is prohibited in competitive sport under the World Anti-Doping Agency code, where it is classified as a metabolic modulator. It is not approved as a prescription medicine in the United States, European Union, or other major markets. Regulatory action has focused on its presence in sports and in products marketed as research chemicals. Because it has no accepted medical indication, supply is often unregulated. This status creates legal and safety uncertainties for anyone who encounters the substance.

Anti-doping laboratories detect GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be used in some programs. Detection depends on factors such as dose, timing, metabolism, and the sensitivity of the assay. Published methods describe limits of detection in the low nanogram per milliliter range for related compounds. Exact detection windows are not fixed for all situations and remain an area of ongoing study.

Products sold as cardarine have been found to contain incorrect compounds, variable amounts, or no active ingredient at all. Independent testing is required to verify identity and purity. Common analytical approaches include high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance for structural confirmation. These methods can distinguish GW501516 from related PPAR agonists and from unrelated steroids. For regulators and researchers, such verification is central to interpreting both biological results and adverse event reports.

Identity and Pharmacological Mechanism

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.

Reference notes

The English word Germany derives from the Latin Germania, which came into use after Julius Caesar adopted it for the peoples east of the Rhine. The German term Deutschland, originally diutisciu land ('the German lands'), is derived from deutsch (cf. Dutch), which descended from Old High German diutisc 'of the people' (from diot or diota 'people'), originally used to distinguish the language of the common people from Latin and its Romance descendants. This in turn descends from Proto-Germanic *þiudiskaz 'of the people' (see also the Latinised form Theodiscus), derived from *þeudō, descended from Proto-Indo-European *tewtéh₂- 'people', from which the word Teutons also originates.

== Mechanism == Blockage of the cystic duct by a gallstone causes a buildup of bile in the gallbladder and increased pressure within the gallbladder. Concentrated bile, pressure, and sometimes bacterial infection irritate and damage the gallbladder wall, causing inflammation and swelling of the gallbladder. Inflammation and swelling of the gallbladder can reduce normal blood flow to areas of the gallbladder, which can lead to cell death due to inadequate oxygen.

Since metabolism focuses on the breaking down (catabolic processes) of molecules and the building of larger molecules from these particles (anabolic processes), the use of glucose and its involvement in the formation of adenosine triphosphate (ATP) is fundamental to this understanding. The most frequent type of glycolysis found in the body is the type that follows the Embden-Meyerhof-Parnas (EMP) Pathway, which was discovered by Gustav Embden, Otto Meyerhof, and Jakob Karol Parnas. These three men discovered that glycolysis is a strongly determinant process for the efficiency and production of the human body. The significance of the pathway shown in the adjacent image is that by identifying the individual steps in this process doctors and researchers are able to pinpoint sites of metabolic malfunctions such as pyruvate kinase deficiency that can lead to severe anemia. This is most important because cells, and therefore organisms, are not capable of surviving without proper functioning metabolic pathways.

Sources: en.wikipedia.org

Reference notes

Allogeneic cultured keratinocytes and fibroblasts in bovine collagen, sold under the brand name Gintuit, is a cellular therapy used for the treatment of mucogingival (the oral mucosa and gingival (gum) tissues of the mouth) conditions. Common adverse reactions observed during clinical trials include sinusitis (sinus inflammation), nasopharyngitis (inflammation of the upper throat, upper respiratory tract infection, aphthous stomatitis (canker sores), and local surgery site reactions such as pain and redness. Allogeneic cultured keratinocytes and fibroblasts in bovine collagen is a cellular sheet that consists of two layers, an upper layer composed of living human keratinocytes (the primary cell type in the skin's outer layer) and a lower layer constructed of bovine-derived collagen, human extracellular matrix proteins (molecules that support and give structure to cells), and living human dermal fibroblasts (skin cells that generate connective tissues). It is the first cell-based product made from allogeneic (cells derived from a donor source that is unrelated to the intended recipient) human cells and bovine collagen approved by the US Food and Drug Administration (FDA). It was approved for medical use in the United States in March 2012.

The Chinese Room (formerly Thechineseroom) is a British video game developer based in Brighton that is best known for exploration games. The company originated as a mod team for Half-Life 2, based at the University of Portsmouth in 2007, and is named after John Searle's Chinese room thought experiment. It was a subsidiary of Sumo Digital from 2018 to 2025.

An Iranian ballistic missile strike damaged an Israeli drone factory in Petah Tikva. On the same day, Iran's army chief, Amir Hatami, stated that if US forces invade the country, "not a single person" among the invaders will survive.

Sources: en.wikipedia.org

Notes from published material

112—single emergency 101—the Fire Service and the Ministry of Emergency Situations 102—the police 103—ambulance 104—gas emergency Moscow's Emergency Medical Service (EMS) is the second most efficient among the world's megacities, according to the consultancy PwC in a study called "Analysis of EMS Efficiency in Megacities of the World".

== Structure == This gene encodes a member of the glutathione peroxidase family, consisting of eight known glutathione peroxidases (GPx1-8) in humans. Mammalian Gpx1 (this gene), Gpx2, Gpx3, and Gpx4 have been shown to be selenium-containing enzymes, whereas Gpx6 is a selenoprotein in humans with cysteine-containing homologues in rodents. In selenoproteins, the 21st amino acid selenocysteine is inserted in the nascent polypeptide chain during the process of translational recoding of the UGA stop codon. In addition to the UGA-codon, a cis-acting element in the mRNA, called SECIS, binds SBP2 to recruit other proteins, such as eukaryotic elongation factor selenocysteine-tRNA specific, to form the complex responsible for the recoding process. The protein encoded by this gene forms a homotetramer structure. As with other glutathione peroxidases, GPx1 has a conserved catalytic tetrad composed of Sec or Cys, Gln, Trp, and Asn, where the Sec is surrounded by four arginines (R 57, 103, 184, 185; bovine numbering) and a lysine of an adjacent subunit (K 91'). These 5 residues bind glutathione (GSH) and are only present in GPx1. Two alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. Glutathione peroxidase 1 is characterized in a polyalanine sequence polymorphism in the N-terminal region, which includes three alleles with five, six or seven alanine (Ala) repeats in this sequence. The allele with five Ala repeats is significantly associated with breast cancer risk.

== External links == Clinical trial number NCT03349060 for "Study to Evaluate Efficacy and Safety of PF-04965842 in Subjects Aged 12 Years And Older With Moderate to Severe Atopic Dermatitis (JADE Mono-1)" at ClinicalTrials.gov Clinical trial number NCT03575871 for "Study Evaluating Efficacy and Safety of PF-04965842 in Subjects Aged 12 Years And Older With Moderate to Severe Atopic Dermatitis (JADE Mono-2)" at ClinicalTrials.gov Clinical trial number NCT03720470 for "Study Evaluating Efficacy and Safety of PF-04965842 and Dupilumab in Adult Subjects With Moderate to Severe Atopic Dermatitis on Background Topical Therapy (JADE Compare)" at ClinicalTrials.gov

Due to the arrangement of the receiver antennas, the sensitive area had a number of side lobes that allowed reception at multiple vertical angles. Typically the operator would use the upper set of antennas at 215 ft (66 m), which had the clearest view of the horizon. Due to the half-wave interference from the ground, the main lobe from this antenna was directed at about 2.5 degrees above the horizontal, with its sensitive region extending from about 1 to 3 degrees. At the ground the gain was zero, which allowed aircraft to escape detection by flying at low altitudes. The second lobe extended from about 6 to 12 degrees, and so on. This left a distinct gap in the reception pattern centred at about 5.2 degrees. This reception pattern provided CH with a relatively accurate way to estimate the altitude of the target. To do this, the motorized switch in the receiver hut was used to disconnect the four receiver masts and instead select the two vertically displaced antennas on one mast. When connected to the radiogoniometer, the output on the display was now effected by the relative signal strength of the two lobes, rather than the relative strengths in X and Y in the horizontal plane. The operator swung the radiogoniometer looking for the peak or minimum reception, as before, and noted the angle. The number reported by the operator was the line-of-sight range to the target, or slant range, which included components of both the horizontal distance and altitude.

Sources: en.wikipedia.org

Frequently asked questions

Is cardarine a selective androgen receptor modulator?

No. Cardarine is a PPARδ agonist, while selective androgen receptor modulators act on androgen receptors. The two classes differ in receptor target and downstream effects.

Why did clinical development stop?

Preclinical rodent studies reported cancers, including liver and bladder tumors, at tested doses. The human relevance of those findings is uncertain, but development was discontinued. No approved human product resulted.

Is cardarine approved for medical use?

No. It remains an investigational compound without approved therapeutic labeling. Sports regulators prohibit its use, and health agencies have warned against consuming it.

What is the main molecular target of cardarine?

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.

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