Cardarine
Also known as: GW501516, GW-501516, Endurobol
PPAR-delta Agonist | Endurance & Fat Metabolism
Overview
Cardarine (GW501516) is a synthetic PPAR-delta (peroxisome proliferator-activated receptor delta) agonist originally developed by GlaxoSmithKline and Ligand Pharmaceuticals in the early 2000s for the treatment of metabolic and cardiovascular diseases, including dyslipidemia, obesity, and diabetes. Despite being almost universally categorized alongside SARMs in the performance enhancement market, Cardarine is not a selective androgen receptor modulator and does not bind to the androgen receptor at all. Its mechanism is entirely distinct: it activates PPAR-delta, a nuclear receptor that regulates fatty acid oxidation, energy expenditure, and lipid metabolism. In preclinical studies, Cardarine demonstrated remarkable effects on endurance capacity, fat oxidation, and lipid profiles. However, development was abandoned by GSK in 2007 after preclinical toxicology studies in rodents revealed an increased incidence of tumors across multiple organ systems when the compound was administered at supratherapeutic doses over extended periods. This cancer signal remains the central controversy and safety concern surrounding Cardarine. The compound has never been approved for human use by any regulatory agency, and no clinical trials have been completed. It is classified as a prohibited substance by the World Anti-Doping Agency (WADA). Despite these concerns, Cardarine continues to be widely available through research chemical suppliers and is used in performance enhancement contexts for its potent endurance-boosting and fat-burning properties.
Key benefits
- Dramatic increase in endurance capacity through enhanced fatty acid oxidation in skeletal muscle
- Promotes fat loss by shifting metabolic fuel preference toward fatty acid utilization over glucose
- Improves lipid profiles: increases HDL cholesterol, decreases LDL cholesterol, and lowers triglycerides
- Non-hormonal mechanism -- does not suppress testosterone or require post-cycle therapy
- No androgenic side effects (no hair loss, no prostate stimulation, no virilization in women)
- Long half-life (16-24 hours) permits convenient once-daily oral dosing
- May offset lipid disruption caused by SARMs or anabolic steroids when used in combination
Mechanism of action
Cardarine acts as a potent and highly selective agonist of PPAR-delta, a nuclear hormone receptor expressed in skeletal muscle, liver, adipose tissue, and the gastrointestinal tract. Upon binding to PPAR-delta, Cardarine triggers a conformational change that promotes heterodimerization with retinoid X receptor (RXR), and the resulting complex binds to PPAR response elements (PPREs) in the promoter regions of target genes. This transcriptional activation upregulates a suite of genes involved in fatty acid oxidation, mitochondrial biogenesis, and energy uncoupling. In skeletal muscle, PPAR-delta activation by Cardarine shifts the metabolic fuel preference from glucose toward fatty acids, dramatically increasing the rate of beta-oxidation. This metabolic reprogramming effectively transforms type II (fast-twitch, glycolytic) muscle fibers toward a more oxidative phenotype, similar to type I (slow-twitch) fibers, which underpins the compound's dramatic effects on endurance capacity. Preclinical studies in mice demonstrated that GW501516 treatment increased running endurance by up to 68% compared to controls. In the liver and adipose tissue, PPAR-delta activation by Cardarine promotes fatty acid catabolism and reduces lipogenesis, resulting in reduced body fat storage and improved lipid profiles (increased HDL, decreased LDL, reduced triglycerides). Critically, Cardarine does not interact with the androgen receptor, does not suppress the hypothalamic-pituitary-gonadal (HPG) axis, and does not affect endogenous testosterone production. This non-hormonal mechanism means it does not cause testosterone suppression and does not require post-cycle therapy.
Molecular data
- Type
- PPAR-delta agonist (C21H18F3NO3S2)
- Half-life
- ~16-24 hours
Indications
What the research community uses this compound for, with self-reported effectiveness.
Performance & Body Composition
Clinical / Investigational (Abandoned)
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Delivery method
| Protocol | Dose | Frequency | Duration |
|---|---|---|---|
| — | 10 mg/day | Once daily | — |
| — | 20 mg/day | Once daily | — |
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Headaches (typically transient, most common in the first week)
- Mild gastrointestinal discomfort (nausea, loose stools, or stomach upset, usually dose-dependent and transient)
Rare side effects
- Insomnia or sleep disturbance
- Mild joint discomfort
- Elevated heart rate during rest (infrequently reported)
Contraindications
- Personal or family history of cancer (the rodent carcinogenicity data warrants extreme caution in individuals with elevated cancer risk)
- Pregnancy or potential pregnancy
- Breastfeeding
- Pre-existing liver disease (limited safety data)
- Individuals under 18 years of age
Monitoring
- Lipid panel (total cholesterol, HDL, LDL, triglycerides): baseline and at 4-8 weeks to track improvements
- Liver function panel (ALT, AST): baseline and mid-cycle as a precaution given limited human safety data
- Fasting blood glucose and HbA1c: baseline and post-cycle (given PPAR-delta's role in glucose metabolism)
- General health screening including physical examination at regular intervals
References
Primary literature and clinical-trial data informing this entry.