It increases the blood flow, acting as a 'masking' agent and allowing other substances into the bloodstream quicker..

very impressive Donny

Thanks D . were there any other substances found in Hock's tests then ?

Don't know, but the presense of a metabolyte of cocaine (ingredient basically), could indicate to testers that there may be other substances involved.
The fact that there was cocaine (or one of its 'ingredients') in his bloodstream is enough for him to get a ban if both tests come back positive.

There are a variety of drugs that can act as masking agents, Viagra being one of them. Basically, anything that can increase bloodflow in the human body can be used, which is why all the scandal broke in the Tour De France a few years back when a previously unknown drug was found in the blood of a lot of riders.

The problem is, the users are always going to be one or two paces in front of the testers, so they'll always have the opportunity to get an advantage.

In itself it can a performance enhancer - just depends what performance you want to enhance!