I would be interested in seeing the actual studies as well. Does not seem that they are posted openly for some reason? This was what I found on a quick google search:
Anti-doping agency warns cheats on the health risks of Endurobol
Benjamin Koh
Doctoral Researcher,
Complementary,
Alternate Medicine at University of Technology, Sydney
The World Anti-Doping Agency (WADA) has taken the unusual step of warning athletes about the health risks of the banned substance GW501516.
In an alert published yesterday, the agency claimed the substance – also known online by its supplement name, Endurobol – was being sold on the black market as an endurance booster and was being abused by athletes.
There is no indication as yet as to how prevalent the use of the drug is, nor what the specific health concerns of the substance were that prompted the global alert, but according to WADA:
The side effect of this chemical compound is so serious that WADA is taking the rare step of warning “cheats” to ensure that there is complete awareness of the possible health risks to athletes who succumb to the temptation of using GW501516 for performance enhancement.
GW501516 was described by WADA as:
a developmental drug that was withdrawn from research by the pharmaceutical company and terminated when serious toxicities were discovered in pre-clinical studies.
Unfortunately, 2009 document (
http://www.toxicology.org/AI/Pub/Tox/2009Tox.pdf) provided by WADA did not shed any light on the reason for the drug termination by the pharmaceutical company and/or WADA’s latest concern.
What we do know is that GW501516 is a developmental drug that was being developed by the major pharmaceutical company GlaxoSmithKline (GSK).
And we know a little about its chemical make-up and potential uses.
Endurobol’s mechanism of action
Peroxisome proliferator-activated receptors (PPARs) are a group of drugs that are believed to act on the nuclear hormone receptors (NHRs) involved in glucose and lipid metabolism.
They belong to a group of receptors called the NHR super family, which also includes receptors for thyroid hormones, steroid hormones and vitamin D.
Three different PPARs — PPAR-alpha (PPARA), PPAR-gamma (PPARG), and PPAR-delta (PPARD) — have been described.
GW501516 (also known as GW501, GW516, GW1516) belongs to family of drugs that act on the PPARD receptors and is an oral drug that is bioactive (has interaction with or effect on cell tissue) in humans.
PPARD is believed to work at the gene level and affects skeletal muscle metabolism. In one laboratory study, PPARD activation seemed to nearly double the performance of running endurance in untrained adult mice.
Other potential functions of GW501516 include its regulation of fat metabolism, glucose uptake in skeletal muscle tissue and an increase in muscle gene expression.
The combined effects of these various functions suggest it has a role in burning fat for energy instead of carbohydrates or muscle protein.
As such, it fits within an area of research into clinical applications for obese patients to lose fat effectively without experiencing muscle catabolism or the effects and satiety issues associated with low blood sugar.
In studies on mice, GW501516 led to increases in muscle mass, which improved glucose tolerance and reduced fat mass accumulation even in mice fed a very high fat diet.
Further rodent studies suggest there may be an increased risk of some forms of tumours in rats and mice administered GW501516. The implication of this finding is at present unknown as the in vitro therapeutic effects of GW501516 on human pancreatic cancer cells is also postulated.
Human health risks
GSK undertook two phase I and one phase II clinical trials for GW501516.
A review of the reports for these shows one phase I clinical trial was terminated – but no reason is provided as to why. The other two trials were listed by GSK as completed.
The terminated Phase I study evaluated the usefulness of the drug in treating patients with heart disease. It also measured a number of other potential markers of drug activity, including levels of lipids and proteins in participants’ blood.
A phase IV clinical study was completed in Australia in 2008. It assessed the application of GW5015156 in the treatment of high blood cholesterol in insulin resistance and obesity.
No adverse events were reported by the authors for the phase IV trials. The authors also cited two earlier clinical studies that showed no significant adverse effect of the drug, including liver or muscle responses in participants treated with GW501516.
Doping
Peroxisome proliferator-activated receptors have been listed as a specific class of substances banned under WADA’s prohibited list since 2009.
Prior to this, the ban was effective only under the generic header of “gene doping” as GW501516 affects gene expression.
According to the Australian Sports Anti-Doping Authority (ASADA) website, PPARs are banned both in and out of competition. But searching the site for GW501516, GW501, GW516, GW1516, GSK-516 and Endurobol all returned negative results.
In the printed version of the current WADA prohibited list, GW501516 is banned under section S4-5b, and in the online version it’s banned under section M3.
This, in and of itself, offers little in the way of explanation for the current – and seemingly urgent – WADA warning. Like many people, I’m hoping for more clarification from WADA in the coming days.
I am also waiting for further updates from representatives at GSK, who I contacted today.