I wouldn't worry about it unless you have a vicodin habit. If you take them too often it could damage your liver. If you only take them every now and then, I wouldn't worry about it. I have taken 4500mg of acetaminophen through vicodin on numerous occasions and have had no negative reactions. It all depends on the frequency of ingestion, so don't worry about it unless you take copious amounts very often.
you know, you could just do a cold water extraction with the vicodin to get all the APAP out and not have to worry about the bad effects. google cold water extraction if you don't know how to do it