Don't mean to revive old posts, but I found this article in the NY Times that's pretty interesting. This appears to be the NFL's take on it:
http://www.nytimes.com/2006/12/08/sport ... ref=sports
Doing some quick research, it appears that the drug operates similar to ephedrine, but the drug lingers in the body longer. As the article mentions, it is illegal for human consumption and is usually used to treat asthma-like conditions in horses. In some of the stuff I read online it appears that this particular drug might have been banned recently - apparently the FDA does not have this ingredient on any approved therapudic drugs since 2006.