GW-501516, widely sold as "Cardarine," is one of the most misclassified compounds in this market:
it is routinely grouped with SARMs but is not one. Getting that right matters, because its
mechanism and — critically — its safety record are different from the SARM class.
Chemical identity & structure.
GW-501516 is a synthetic PPARδ (peroxisome proliferator-activated receptor delta) agonist, a
small-molecule research chemical developed in the 1990s (originally a GlaxoSmithKline/Ligand
collaboration). It is not a hormone or a peptide and does not act on the androgen receptor, which
is what distinguishes it from SARMs despite the shared marketing shelf.
Mechanism of action.
PPARδ is a nuclear receptor that regulates fatty-acid metabolism and oxidative capacity in
skeletal muscle. Agonism is reported in animal models to shift fuel use toward fat oxidation and
to increase expression of genes associated with endurance and mitochondrial function — the basis
for the "exercise mimetic" framing in the literature.
Key research findings.
Rodent studies reported increased running endurance and favourable metabolic-marker changes.
These findings drove substantial interest, but they sit against a decisive safety finding (below)
and a near-total absence of human efficacy data.
The research / citation base.
GW-501516's development was **discontinued after long-term rodent studies showed it induced
cancers across multiple organ systems at the doses and durations tested. It is not an approved
drug**, was never completed through human trials for performance or metabolic indications, and is
on the WADA Prohibited List — WADA took the unusual step of issuing a public health warning
about it. This carcinogenicity signal is the single most important fact about the compound and
belongs at the centre of any honest summary.
Human clinical trial data.
In the first-in-human study by Sprecher and colleagues (2007), healthy volunteers were allocated placebo (n=6) or one of two GW501516 dose levels (n=9 each) for 2 weeks (PubMed). In the study by Olson and colleagues (2012), GW501516 at one of three dose levels or placebo was given for 12 weeks to patients (n=268) with high-density lipoprotein cholesterol <1.16 mmol/L (PubMed).
Quality & sourcing notes.
As a small molecule, a COA should report identity and purity by HPLC and mass spectrometry.
Mislabelling and contamination are documented across this category. The more important sourcing
note is interpretive: no COA addresses the carcinogenicity finding, which is a property of the
molecule itself, not of any particular batch.
*Research-use note: This monograph is an educational summary of the published research literature.
GW-501516 is not an approved drug, is prohibited in sport, and rodent studies reported
carcinogenicity; it is described here for research context only. Nothing here is medical advice or
a usage recommendation.*