LC-MS/MS raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-02 and is reviewed periodically as new material appears.
Safety concerns emerged from long-term animal studies. In rodents given the compound for extended periods, researchers found an increased incidence of certain cancers, including liver and bladder tumors. These findings contributed to the discontinuation of clinical development. Whether similar risks apply to short-term or low-level exposure in humans is not established, and controlled human safety data are limited. The relevance of high-dose rodent carcinogenicity findings to human use remains a subject of debate.
Human trials of GW501516 were small and short in duration. They examined lipid levels, glucose handling, and other metabolic markers, but the programs were halted after the animal cancer findings. No approved therapeutic product exists, and published human data are insufficient for establishing long-term safety. Reports of use for athletic performance come mainly from non-clinical settings and cannot be verified through controlled trials. Independent testing of products sold as cardarine has found inconsistent purity and labeling.
Regulatory bodies treat GW501516 as a prohibited substance in competitive sport. The World Anti-Doping Agency added it to the prohibited list, and it falls under classes covering metabolic modulators and hormone-related agents. It is not approved by drug regulators for human use, and it is not a lawful dietary supplement. Products sold under the cardarine name may contain unlisted ingredients or different compounds. Because no approved product exists, quality and identity are not guaranteed by pharmaceutical manufacturing standards.
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.
| Property | Value | Notes |
|---|---|---|
| Primary target | PPARδ (NR1C2) | Nuclear receptor involved in lipid metabolism |
| Preclinical effect | Increased fatty acid oxidation | Observed in rodent studies |
| Key safety signal | Tumors in rodents after long-term exposure | Contributed to halted clinical development |
| Human trial status | No approved product; development stopped | Limited short-term metabolic data |
| Sport regulatory status | Prohibited at all times | WADA hormone and metabolic modulators class |
In the fitness and bodybuilding literature, cardarine is frequently discussed as an endurance agent or fat-loss compound, although such claims are not supported by robust clinical evidence. Online descriptions often mix animal data, user anecdotes, and marketing language. Researchers who study PPARδ agonists distinguish between receptor activation in controlled experiments and unsupervised use of unverified products. The latter introduces unknown purity, dose, and interactions, making reported experiences difficult to interpret scientifically.
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.
In laboratory settings, cardarine is studied as a tool compound for probing PPARδ biology. Published experiments often use cell cultures, rodent models, or isolated tissues. Some investigations focus on metabolic effects, while others assess potential risks such as carcinogenicity observed in long-term animal studies. Because human trials are sparse, most knowledge comes from preclinical work and adverse event reports. Scientific literature frequently notes the gap between animal findings and human outcomes. The compound is not a dietary supplement and is not intended for human consumption.
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.
Regulatory treatment of cardarine differs by context and jurisdiction. In competitive sport, the World Anti-Doping Agency lists PPARδ agonists, including GW501516, as prohibited at all times. Outside sport, it lacks approval as a prescription medicine in major drug markets, and products sold for human consumption may be treated as unapproved drugs. Some countries also restrict importation or sale through general consumer protection and medicines laws. These classifications affect availability, testing, and legal risk without establishing therapeutic value.
Because cardarine is not an approved medicine, no pharmacopeial monograph defines its identity, purity, or storage requirements. Laboratories typically rely on in-house methods and reference standards when testing materials labeled as GW501516. Certificates of analysis may report purity and identity for a specific batch, but their scope varies and they do not guarantee safety or legal status. Independent verification can include high-performance liquid chromatography, mass spectrometry, nuclear magnetic resonance, and elemental analysis. The distinction between research chemical labeling and human use is significant because quality standards and oversight differ.
Cardarine can be detected in biological samples and product materials using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method separates compounds by chromatography and identifies them by mass-to-charge transitions, allowing low-level detection in urine or blood. Sample preparation often involves enzymatic hydrolysis, solid-phase extraction, or protein precipitation. Certified reference materials and isotope-labeled internal standards improve quantification. Detection windows depend on metabolism, matrix, and assay sensitivity, so no single universal window applies.
Veneer is obtained either by "peeling" the trunk of a tree or by slicing large rectangular blocks of wood known as flitches. The appearance of the grain and figure in wood comes from slicing through the growth rings of a tree and depends upon the angle at which the wood is sliced. There are three main types of veneer-making equipment used commercially:
Adrenal androgen stimulating hormone (AASH), also known as cortical androgen stimulating hormone (CASH), is a hypothetical hormone which has been proposed to stimulate the adrenal glands to produce adrenal androgens such as dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione (A4). It is hypothesized to be involved in adrenarche and adrenopause. The existence of this hormone is controversial and disputed and it has not been identified to date. A number of other mechanisms and/or hormones may instead play the functional role of the so-called AASH.
However, in the 2025 study, time to maximal effects was about 2.5 hours orally and about 1.2 hours intravenously. In an earlier 2016 study, intravenous LSD effects similarly peaked after about 1.7 hours. For comparison, intravenous dimethyltryptamine (DMT) given as a bolus has been found to produce maximal effects after about 2 minutes and intravenous psilocybin given over 60 seconds produces peak effects after about 4 minutes. Doses of LSD are said to be similar by oral and injectable routes, with the exception of intrathecal injection, in which the dose is reduced to about one-third of usual. The plasma protein binding of LSD in humans is unknown, but it is 65 to 90% bound to plasma proteins in guinea pigs.
End groups are an important aspect of polymer synthesis and characterization. In polymer chemistry, they are functional groups that are at the very ends of a macromolecule or oligomer (IUPAC). In polymer synthesis, like condensation polymerization and free-radical types of polymerization, end-groups are commonly used and can be analyzed by nuclear magnetic resonance (NMR) to determine the average length of the polymer. Other methods for characterization of polymers where end-groups are used are mass spectrometry and vibrational spectrometry, like infrared and raman spectroscopy. These groups are important for the analysis of polymers and for grafting to and from a polymer chain to create a new copolymer. One example of an end group is in the polymer poly(ethylene glycol) diacrylate where the end-groups are circled.
==== Distribution ==== The majority of carvedilol is bound to plasma proteins (98%), mainly to albumin. Carvedilol is a basic, hydrophobic compound with a steady-state volume of distribution of 115 L. Plasma clearance ranges from 500 to 700 mL/min. Carvedilol is highly lipophilic and easily crosses the blood–brain barrier in animals, and hence is not thought to be peripherally selective.
Sources: en.wikipedia.org
The CDC defines an adult (a person aged 20 years or greater) with a body mass index (BMI) of 30 or greater as obese and an adult with a BMI of 25.0 to 29.9 as overweight. Obesity in adults is divided into three categories. Adults with a BMI of 30 to 34.9 have class 1 obesity; adults with a BMI of 35 to 39.9 have class 2 obesity; adults with a BMI of 40 or greater have class 3 obesity, which is also known as extreme or severe obesity (and was formerly known as morbid obesity). Children (persons aged 2 to 19 years) with a BMI at or above the 95th percentile of children of the same age and sex are defined as obese, and children with a BMI at or above the 85th percentile but less than the 95th percentile are defined as overweight. Compared to non-obese Americans, between 2001 and 2016, obese Americans incurred an average of $2,505 more in medical expenses annually, and in 2016, the aggregate medical cost due to obesity in the United States of America was $260.6 billion. However, some evidence suggests the lifetime cost of medical treatment for obese individuals is lower than for healthy weight individuals. This is because healthy weight people live longer statistically and tend to develop chronic diseases that need to be continually treated into old age, whereas obese people tend to die from metabolic diseases at younger ages and avoid some of those protracted medical costs.
==== Dietary iron uptake ==== The absorption of dietary iron is a variable and dynamic process. The amount of iron absorbed compared to the amount ingested is typically low, but may range from 5% to as much as 35% depending on circumstances and type of iron. The efficiency with which iron is absorbed varies depending on the source. Generally, the best-absorbed forms of iron come from animal products. Absorption of dietary iron in iron salt form (as in most supplements) varies somewhat according to the body's need for iron, and is usually between 10% and 20% of iron intake. Absorption of iron from animal products, and some plant products, is in the form of heme iron, and is more efficient, allowing absorption of from 15% to 35% of intake. Heme iron in animals is from blood and heme-containing proteins in meat and mitochondria, whereas in plants, heme iron is present in mitochondria in all cells that use oxygen for respiration. Like most mineral nutrients, the majority of the iron absorbed from digested food or supplements is absorbed in the duodenum by enterocytes of the duodenal lining. These cells have special molecules that allow them to move iron into the body. To be absorbed, dietary iron can be absorbed as part of a protein such as heme protein or iron must be in its ferrous Fe2+ form. A ferric reductase enzyme on the enterocytes' brush border, duodenal cytochrome B (Dcytb), reduces ferric Fe3+ to Fe2+.
The transition from wakefulness to sleep (REM sleep or NREM sleep) is associated with a reduction in upper-airway muscle tone. During REM sleep, the muscle tone of the throat and neck, as well as that of the vast majority of skeletal muscles, is almost completely relaxed. This allows the tongue and soft palate/oropharynx to relax, reducing airway patency and potentially impeding or completely obstructing air flow into the lungs during inspiration, resulting in reduced respiratory ventilation. If reductions in ventilation are associated with sufficiently low blood-oxygen levels or with sufficiently high breathing efforts against an obstructed airway, neurological mechanisms may trigger a sudden interruption of sleep, called a neurological arousal. This arousal can cause an individual to gasp for air and awaken. These arousals rarely result in complete awakening but can have a significant negative effect on the restorative quality of sleep. In significant cases of OSA, one consequence is sleep deprivation resulting from the repetitive disruption and recovery of sleep activity. This sleep interruption in Stage 3 NREM sleep (also called slow-wave sleep) and in REM sleep can interfere with normal growth patterns, healing, and immune response, especially in children and young adults. The fundamental cause of OSA is a blocked upper airway, usually behind the tongue and epiglottis, whereby the otherwise patent airway, in an erect, awake patient, collapses when the patient lies on his or her back and loses muscle tone upon entering deep sleep.
== History == The predecessor of LGD-4033, LG121071 (LGD-121071), was discovered by Ligand Pharmaceuticals and was first described in the literature in January 1999. It was the first orally active nonsteroidal androgen receptor agonist to be discovered. LG121071 is a tricyclic quinoline derivative, and is structurally distinct from arylpropionamide SARMs like andarine and enobosarm (ostarine). LGD-2226, a bicyclic quinoline SARM, was subsequently developed by Ligand Pharmaceuticals and TAP Pharmaceuticals in 2001. Other quinoline SARMs, like LGD-2941 and LGD-3303, were also subsequently developed by Ligand Pharmaceuticals prior to the development of LGD-4033. LGD-4033 was developed by Ligand Pharmaceuticals and was first described in the literature in 2010. On the basis of a favorable preclinical profile, phase 1 clinical trials of LGD-4033 began in 2009. The results of a single-dose phase 1 clinical trial were published as a conference abstract in 2010 and the findings of a multi-dose phase 1 trial were published as a journal article in 2013. A third phase 1 trial was also conducted. By 2012, a phase 2 trial of LGD-4033 for the treatment of muscle wasting related to cancer cachexia, acute rehabilitation (e.g., hip fracture), and acute illness was being prepared by Ligand Pharmaceuticals. On 22 May 2014, Viking Therapeutics licensed the developmental rights of LGD-4033 from Ligand Pharmaceuticals and intended to advance the compound into mid-to-late-stage clinical trials.
HT-2157 (former development code SNAP-37889) is a drug which acts as a selective non-peptide antagonist for the receptor GAL-3, which is usually activated by the neuropeptide galanin. Blocking this receptor with HT-2157 produced increased serotonin release, as well as producing antidepressant and anxiolytic effects in animal studies, and it was also being researched for treatment of cognitive dysfunction. All human clinical trials were terminated due to safety concerns however, and new GAL-3 antagonists are now being sought instead.
Sources: en.wikipedia.org
Human Genome Project (HGP) A collaborative international scientific research project with the goal of sequencing all of the chromosomal DNA and identifying and mapping all of the genes within human cells, and ultimately of assembling a complete reference genome for the human species. The project was launched in 1990 by a consortium of federal agencies, universities, and research institutions and was declared complete in 2003. Because each individual human being has a unique genome, the finished reference genome is a mosaic of sequences obtained by sampling DNA from thousands of individuals across the world and does not represent any one individual.
== Biosafety == Xenobiological systems are designed to convey orthogonality to natural biological systems. A (still hypothetical) organism that uses XNA, different base pairs and polymerases and has an altered genetic code will hardly be able to interact with natural forms of life on the genetic level. Thus, these xenobiological organisms represent a genetic enclave that cannot exchange information with natural cells. Altering the genetic machinery of the cell leads to semantic containment. In analogy to information processing in IT, this safety concept is termed a "genetic firewall". The concept of the genetic firewall seems to overcome a number of limitations of previous safety systems. A first experimental evidence of the theoretical concept of the genetic firewall was achieved in 2013 with the construction of a genomically recoded organism (GRO). In this GRO all known UAG stop codons in E.coli were replaced by UAA codons, which allowed for the deletion of release factor 1 and reassignment of UAG translation function. The GRO exhibited increased resistance to T7 bacteriophage, thus showing that alternative genetic codes do reduce genetic compatibility. This GRO, however, is still very similar to its natural "parent" and cannot be regarded to have a genetic firewall. The possibility of reassigning the function of large number of triplets opens the perspective to have strains that combine XNA, novel base pairs, new genetic codes, etc. that cannot exchange any information with the natural biological world.
Five-door four-seat hatchback Three-door four-seat hatchback Five-door four-seat station wagon (also as a van in Japan) Three-door four-seat station wagon Three-door two-seat van with an extended roof profile
== External links == Interview with Roderick MacKinnon by Harry Kroto Freeview video provided by the Vega Science Trust. Website of his lab at The Rockefeller University Ion Channel Chemistry: The Electrical System of Life Transcribed video of a May 2008 talk by MacKinnon, sponsored by the Oregon State University Libraries. Nobel Lecture by Roderick MacKinnon, 2003 Introduction to Neuroscience by Donald C.Cooper Roderick MacKinnon on Nobelprize.org
== Venture capital arm == In early 2021, Dexcom launched Dexcom Ventures, a venture capital arm focused on emerging continuous glucose monitoring technologies and devices measuring the levels of other types of substances and analytes. In practice, Dexcom Ventures has also invested in cybersecurity platforms for the software used in medical devices.
Sources: en.wikipedia.org
Rodent studies reported increased endurance and fat oxidation after GW501516 exposure. Long-term studies also found higher rates of some tumors, which led to halted development.
Small short-term human trials examined metabolic markers such as lipids and glucose. The trials did not continue after rodent cancer findings, so long-term human safety is unknown.
Controlled human trials have not established a performance benefit. Anecdotal reports exist, but they are not reliable evidence.
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.