PPARδ comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-04-29. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Laboratory studies indicate that GW501516 activates PPARδ, a nuclear receptor involved in fatty acid oxidation and energy metabolism. In rodent experiments, treated animals often showed increased endurance and reduced fat mass. These effects were observed under controlled conditions and do not establish safe or effective use in humans. The exact dose-response relationship in humans remains poorly characterized. Species differences in metabolism can affect how results translate across animals and people.
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.
| 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. |
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.
Handling and quality assessment of cardarine reference material follow general laboratory practices for poorly characterized compounds. It typically appears as a white to off-white powder and is sparingly soluble in water but soluble in organic solvents such as dimethyl sulfoxide and ethanol. Storage recommendations usually specify a cool, dry, dark place, with long-term storage at low temperature and desiccation. Purity may be checked by high-performance liquid chromatography with ultraviolet detection, while identity is confirmed by mass spectrometry and nuclear magnetic resonance. No pharmacopeial monograph exists, so reported purity and stability depend on the supplier’s methods.
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.
== Synthesis == To begin, this type of collagen is synthesized by the assembly of a specific trimer, when the three NC1 domains initiate molecular interactions between the three α-chains. Protomer trimerization then proceeds from the carboxy terminus to yield the fully assembled protomer. The next step in assembly is collagen IV dimerization. Two collagen IV protomers associate through the carboxy-terminal NC1 trimer to form the NC1 hexamer. These interactions form the core of the type IV collagen scaffold. The scaffold evolves into a collagen IV superstructure by "end-to-end" and lateral connections between collagen IV protomers. The collagen molecule is then formed. Lastly, the type IV collagen molecules bind together to form a complex protein network. To summarize, the process of collagen synthesis occurs mainly in the cells of fibroblasts which are specialized cells with the main function of synthesizing collagen. Collagen synthesis occurs both intracellularly and extracellularly. However, when looking specifically at type IV collagen, it is mostly synthesized extracellularly.
==== Iraq ==== In December 2004, the task forces based on 2–325th AIR and 3–325th AIR were deployed to Iraq to provide security for the country's national elections in which more than eight million Iraqis voted.
The initial effects of exposure were coughing, severe eye irritation, a feeling of suffocation, burning in the respiratory tract, blepharospasm, breathlessness, stomach pains, and vomiting. People alerted by these symptoms fled from the plant. Those who ran inhaled more than those in vehicles. Owing to their height, children and other residents of shorter stature inhaled higher concentrations, as methyl isocyanate gas is approximately twice as dense as air and in an open environment has a tendency to fall toward the ground. Thousands of people had died by the following morning. Primary causes of deaths were choking, reflexogenic circulatory collapse, and pulmonary oedema. Findings during autopsies revealed changes not only in the lungs but also cerebral oedema, tubular necrosis of the kidneys, fatty degeneration of the liver, and necrotising enteritis. The individuals who did not die suffered from cancer, blindness, loss of livelihood, and financial strain.
== Overdose == The median lethal dose of THC in humans is not fully known as there is conflicting evidence. A 1972 study gave up to 90 mg/kg of THC to dogs and monkeys without any lethal effects. Some rats died within 72 hours after a dose of up to 36 mg/kg. A 2014 case study based on the toxicology reports and relative testimony in two separate cases gave the median lethal dose in humans at 30 mg/kg (2.1 grams THC for a person who weighs 70 kg; 154 lb; 11 stone), observing cardiovascular death in the one otherwise healthy subject of the two cases studied. A different 1972 study gave the median lethal dose for intravenous THC in mice and rats at 30–40 mg/kg. A 2020 fact sheet published by the US Drug Enforcement Administration stated that "no deaths from overdose of marijuana have been reported."
High entry barriers because of demanding technology: the construction of a large-scale plant for the production of biopharmaceuticals by cell culture fermentation costs around $500 million and takes four to six years. As the specifications of the plant and process types for biopharmaceuticals differ substantially from traditional chemical synthesis, they cannot be produced in conventional multipurpose fine chemical plants. High financial exposure, due to high capital intensity (as massive investments are needed at a time when chances of success are still very low) and risk of batch failures (contamination). Unlike the biopharmaceutical start-ups, the emerging big biopharmaceutical companies are adopting the same opportunistic outsourcing policy as larger pharmaceutical companies. Thus, Amgen, Biogen Idec, Eli Lilly, Johnson & Johnson (J&J), Medimmune, Novartis, Roche-Genentech and Pfizer are investing heavily in in-house manufacturing capacity. With three plants in the US, two in Japan and one each in Germany and Switzerland, Roche has the largest production capacity. New developments in expression systems for mammalian and plant cell technology could reduce capacity requirements substantially: the titer in large-scale mammalian production, 2–3 grams/liter, is expected to double to 5–7 by 2015 go up to 10 by 2020. Furthermore, the widespread application of "single-use disposable bioprocessing technology" advantageously substitutes for stainless steel production trains, at least for short production campaigns.
Sources: en.wikipedia.org
== Mechanism == Myelofibrosis is a clonal neoplastic disorder of hematopoiesis, the formation of blood cellular components. It is one of the myeloproliferative disorders, diseases of the bone marrow in which excess cells are produced at some stage. Production of cytokines such as fibroblast growth factor by the abnormal hematopoietic cell clone (particularly by megakaryocytes) leads to replacement of the hematopoietic tissue of the bone marrow by connective tissue via collagen fibrosis. The decrease in hematopoietic tissue impairs the patient's ability to generate new blood cells, resulting in progressive pancytopenia, a shortage of all blood cell types. However, the proliferation of fibroblasts and deposition of collagen is a secondary phenomenon, and the fibroblasts themselves are not part of the abnormal cell clone. In primary myelofibrosis, progressive scarring, or fibrosis, of the bone marrow occurs, for the reasons outlined above. The result is extramedullary hematopoiesis, i.e. blood cell formation occurring in sites other than the bone marrow, as the hemopoietic cells are forced to migrate to other areas, particularly the liver and spleen. This causes an enlargement of these organs. In the liver, the abnormal size is called hepatomegaly. Enlargement of the spleen is called splenomegaly, which also contributes to causing pancytopenia, particularly thrombocytopenia and anemia. Another complication of extramedullary hematopoiesis is poikilocytosis, or the presence of abnormally shaped red blood cells.
=== Hearing loss === It is not known whether ACE inhibitors or other treatments affect hearing loss. For those with classic Alport syndrome, hearing aids are often required in teenage or young adult years.
Collagen alpha-1(VIII) chain is a protein that in humans is encoded by the COL8A1 gene. This gene encodes one of the two alpha chains of type VIII collagen. The gene product is a short chain collagen and a major component of the basement membrane of the corneal endothelium. The type VIII collagen fibril can be either a homo- or a heterotrimer. Alternatively spliced transcript variants encoding the same isoform have been observed.
=== Michael McDonald years === Under contract to release another album in 1976, the Doobies were at a crossroads. Their primary songwriter and singer remained unavailable, so they turned to McDonald and Porter for material to supplement that of Simmons. The resulting LP, Takin' It to the Streets, debuted a radical change in their sound. Their electric guitar-based rock and roll gave way to a more soft rock and blue-eyed soul sound, emphasizing keyboards and horns and subtler, more syncopated rhythms. Baxter contributed jazz-inflected guitar stylings reminiscent of Steely Dan, along with unusual, complex harmony and longer, more developed melody. Above all, McDonald's voice became the band's new signature sound. Takin' It to the Streets featured McDonald's title track and "It Keeps You Runnin'", both hits. (A second version of "It Keeps You Runnin'", performed by Carly Simon, appeared on her album Another Passenger, with the Doobies backing her.) Bassist Porter wrote and sang "For Someone Special" as a tribute to the absent Johnston. A greatest hits compilation, Best of the Doobies, followed before year's end. (In 1996, the Recording Industry Association of America certified Best of the Doobies "Diamond" for sales in excess of 10 million units.) Their new sound was further refined, and McDonald's dominant role cemented with 1977's Livin' on the Fault Line. It featured a recording of the Motown classic "Little Darling (I Need You)" and "Echoes of Love", which had been written by Willie Mitchell for, but not recorded by, Al Green.
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.
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.