Wednesday, 30 July 2014

GW501516: Update on endurobol and doping: some thoughts about dosing

In a previous blog [1], I noted that there was no evidence in animals that endurobol improved performance in animals. I must apologise as I missed a rather important paper from Ron Evans group in 2008 that showed just that. The performance effect was only seen if the mice were also doing exercise training [2].

What is interesting is the doses that were used in this study. The four-week program of exercise training was paired with 5 mg/kg/day of the drug. This is at the low range of the long-term (2 year) toxicity study done by Glaxo [3], which varied from 0 – 80 mg/kg/day. But some adverse effects were still seen at the 5mg/kg/day level.

Interestingly one anonymous commentator on my previous blog said that he/she knew people who have been using it at a dosage of 10 mg per day for fat loss purposes and 20 mg per day for a performance enhancing benefit. Indeed some companies are selling pills of 5 mg size [4]. However, these doses are far lower than are shown to work in the Evans paper (for an average 85 kg human, the “Evans” dose should be 425 mg/day  - or three full bottles every day of the pills that some manufacturers are selling.

The usual caveats apply. There are long-term toxicity effects of this compound and it is generally easier to show performance effects in laboratory rats and mice than highly fit trained athletes.

  2.  Narkar VA, Downes M, Yu RT et al (2008) AMPK and PPARdelta agonists are exercise mimetics. Cell 134:405-415.
  3.   Toxicological Sciences Volume 108, Number 1, March 2009 Abstracts # 895 and 896    

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