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Background And Regulatory History — Deep Dive

By Editorial Desk · published 2026-07-14 · last reviewed 2026-07-28 · News

The short version of GW501516 fits in a sentence. The long version — which is the one that helps — is below.

Reviewed 2026-07-28. Anything still debated is marked as such rather than presented as settled.

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.

Identity and Pharmacological Classification

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.

PPARδ is a nuclear receptor that influences transcription of genes involved in fatty acid oxidation, lipid transport, and energy homeostasis. GW501516 binds and activates this receptor with high selectivity relative to PPARα and PPARγ in laboratory assays. Activation alters expression of target genes in skeletal muscle, liver, and adipose tissue in animal models. The exact clinical consequences of these changes in humans remain incompletely characterized, and observed effects in animals do not establish therapeutic benefit or safety.

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.

Cardarine as Investigational PPARδ Agonist

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.

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Regulation and Analytical Detection

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.

Background from the literature

=== Elimination === Testosterone and its metabolites are eliminated in urine. It is excreted mainly as androsterone glucuronide and etiocholanolone glucuronide. It is also excreted to a small extent as other conjugates such as testosterone glucuronide (1%), testosterone sulfate (0.03%), and androstanediol glucuronides. Only a very small amount of testosterone (less than 0.01%) is found unchanged in the urine.

=== COVID 19 === The COVID 19 pandemic marked a new chapter in Hetero’s public health contributions. In March 2020, as the pandemic took hold, Hetero donated INR 10 crore to the Telangana government’s COVID relief fund, composed of 5 crores in direct funding and 5 crores in essential medicines including Hydroxychloroquine Sulphate, Lopinavir/Ritonavir and Oseltamivir. During this period, Hetero also began supplying medicines to countries such as the United States, Italy, Spain, Israel, and Algeria. In May 2020, Hetero entered a licensing agreement with Gilead Sciences to manufacture and distribute a generic version of Remdesivir in 127 countries. The Drug Controller General of India granted manufacturing and marketing approval on 21 June 2020, making Covifor the first generic Remdesivir approved in India. An initial consignment of 20000 Vials was distributed within India across major cities including Hyderabad, Delhi, Mumbai, Kolkata and Chennai, priced at ₹5400 per vial. By August 2020, Hetero had supplied approximately 800000 doses of Remdesivir in India alone, treating more than 100000 patients. In the same month, Hetero received authorization from the South African Health Products Regulatory Authority (SAHPRA) to import 'Remdesivir' in South Africa for the treatment for Covid-19, and committed to supplying 60000 vials a month. In July 2020, Hetero received approval from the DCGI to manufacture and market a generic version of Favipiravir tablets under the name Favivir, which is used to treat patients with mild to moderate COVID-19 symptoms.

== Sublethal effects == When an insect population is exposed to pesticide concentrations that are sublethal, surviving individuals may experience a variety of sublethal effects (symptoms). These effects can influence its biology, behavior, and long-term population dynamics. Documented sublethal responses include reduced or increased reproductive capacity, shortened or lengthened lifespan, altered developmental timing or deformities, disrupted feeding activity, and changes in foraging or movement patterns. Over time, these physiological and behavioral changes can slow population growth, disrupt ecological interactions, or in some cases, lead to compensatory increases in reproduction as a stress response. Sublethal exposure can lead to pesticide resistance. Insects that survive may carry genetic traits that enable tolerance, and when these individuals reproduce, resistance can spread through the population and result in decreased long-term pesticide effectiveness. Understanding sublethal effects is critical for integrated pest management strategies and for evaluating the ecological risk of pesticide use in agricultural and natural ecosystems.

Sources: en.wikipedia.org

Further detail

After the discovery of the gene encoding myostatin in 1997, several laboratories cloned and established the nucleotide sequence of a myostatin gene in two breeds of cattle, Belgian Blue and Piedmontese. They found mutations in the myostatin gene (various mutations in each breed) which in one way or another lead to absence of functional myostatin. Unlike mice with a damaged myostatin gene, in these cattle breeds, muscle cells multiply rather than enlarge. People describe these cattle breeds as "double-muscled", but the total increase in all muscles is no more than 40%. Animals lacking myostatin or animals treated with substances such as follistatin that block the binding of myostatin to its receptor have significantly larger muscles. Thus, reduction of myostatin could potentially benefit the livestock industry, with even a 20 percent reduction in myostatin levels potentially having a large effect on the development of muscles. However, the animal breeds developed as homozygous for myostatin deficiency have reproduction issues due to their unusually heavy and bulky offspring, and require special care and a more expensive diet to achieve a superior yield. This negatively affects economics of myostatin-deficient breeds to the point where they do not usually offer an obvious advantage. While hypertrophic meat (e.g.

=== Prosecution in the United States === Following his capture Noriega was transferred to a cell in the Miami federal courthouse, where he was arraigned on the ten charges which the Miami grand jury had returned two years earlier. The trial was delayed until September 1991 over whether Noriega could be tried after his detention as a prisoner of war, the admissibility of evidence and witnesses, and how to pay for Noriega's legal defense. The trial ended in April 1992, when Noriega was convicted on eight of the ten charges of drug trafficking, racketeering, and money laundering. On July 10, 1992, Noriega was sentenced to 40 years in prison. In pre-trial proceedings, the government stated that Noriega had received $322,000 from the U.S. Army and the CIA. Noriega insisted that he had in fact been paid close to $10,000,000, and that he should be allowed to testify about the work he had done for the U.S. government. The district court held that information about the operations in which Noriega had played a part supposedly in return for payment from the U.S. was not relevant to his defense. It ruled that "the tendency of such evidence to confuse the issues before the jury substantially outweighed any probative value it might have had." One of the witnesses in the trial was Carlton, who had previously flown shipments of drugs for Noriega. Information about Noriega's connections to the CIA, including his alleged contact with Bush, were kept out of the trial. After the trial, Noriega appealed this exclusionary ruling by the judge to the Eleventh Circuit Court of Appeals.

The precise direct molecular mechanism of action by which bromantane ultimately acts as a dopamine synthesis enhancer is unknown. However, it has been determined that activation of certain cAMP-, Ca2+-, and phospholipid-dependent protein kinases such as protein kinase A and especially protein kinase C corresponds with the manifestation of the pharmacological effects of bromantane. Bromantane may activate intracellular signaling cascades by some mechanism (e.g., agonizing some as-yet-undetermined receptor) to in turn activate protein kinases, which in turn cause increased transcription of TH and AAAD. The related drugs amantadine and memantine also have many properties similar to those of bromantane. Researchers discovered that amantadine and memantine bind to and act as agonists of the σ1 receptor (Ki = 7.44 μM and 2.60 μM, respectively) and that activation of the σ1 receptor is involved in the central dopaminergic effects of amantadine at therapeutically relevant concentrations; the authors of the study stated that this could also be the mechanism of action of bromantane, as it is in the same family of structurally related compounds and evidence suggests a role of dopamine in its effects. But this could also be seen as evidence of the contrary since bromantane has effects that are distinctly different from amantadine and memantine.

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 cardarine also known as?

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.

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