I just took (and aced) the PTCB.
You should definitely know basic calculations (500 mg tid x 10 d = how many 250 mg tabs?), brand/generic names, which drugs are controls and what that means for refills/returns, and the laws/bills regarding pharmacy.
I didn't study any of the laws and bills, thinking it wouldn't be on there, but there were at least 4-5 questions regarding that on there.
Also, I got hit with a bunch of days supply questions regarding insulin, so make sure you know that too.
All in all, it wasn't that hard of a test, and with a little studying, you should be fine.
Good luck.