here's something I just posted on another lifting site, so I'll paste it here....
tommy thompson banned it in '04 or there abouts; however, as recently as a year or so ago the ban was lifted. Clen is a whole lot better than ephedrine, but for the money? Who knows. Anyway, I get mine from a company called DMD pharmaceuticals--the price has gone up since the good old days before tommy got his paws ito the scene; the doseage available is, in theory, 12.5 mg of ephedrine w/ 200 mg of guaifensin, & it is marketed as it always was, as a bronchodilator. Since I seriously doubt anyone is really regulating seriously this side of the OTC market, who knows how much of whatever is in it. It doesn't light my fuse like those itty bitty white crosses that first came out from AST (these are considerably larger tabs).
Regardless of all that, here is how I understand ephedra/ephedrine: ephedra is the basic herb that ephedrine comes from, so a dose can not really be standardized beyond doubt; ephedrine hcl is the product made from the herb ephedra, &, again in theory, the dose should be standardized (but that's all in how much you trust the people making the stuff). As I see it, & I may see it inaccurately) an analogy would be the coca leaf vs powdered cocaine. And, once again, who knows what's been done to that g of coke before you got a hold of it. But, powdered cocaine can be a standardized dose as opposed to chewing on coca leaves.
If you are interested, do a couple of hits on the wikipedia: look up ephedrine & then look up meth amphetamine; I'm no chemistry major, just what I had to take to get into nsg school, but looking at the diagram, there is not a whole helluvalotta difference between the two molecularly. The atoms are arranged slightly different if I remember correctly & there is something different about a couple of the bonds, but, I have little doubt that one is a precursor to the other. Not that I care about that.