Not sure if this applies to all addictive substances, but I noticed today that with booze, you have to fail the fort save and take the drunk penalties to remove the addiction penalty. It seems to me that simply drinking alcohol should really count as taking your "fix" and you should not need to become drunk to counter it.
I always thought alcoholics were drunk very often.
It actually made perfect sense to me when I was playing an alcoholic. The more you use a substance, the more resistant you become, the more you need to get drunk.
Especially in the case of people who are really fit or have large body mass, it takes more alchohol to get drunk.
It was rough lyfe trying to get drunk as a dwarf with 18 con, resist poison and great fortitude let me tell you =(