be careful of pills - they oxidize and render the NAC useless.
this is why the CFF clinical trials are using fizzy NAC (tablet that you drop in water to dissolve) - these tablets hold their integrity better.
supplements aren't regulated inthe US as you know - whereas in Europe and Canada they are. So buying fizzy NAC from regulated areas is important.
you can get more details about where those of us who use NAC get it on my blog