RegEx is your friend for such things!
To capture "cialis" without catching instances of "specialist" you need to use RegEx instead of Contains and define the beginning with ^ and the end with $ (and it is recommended to use (?i) to make the string Case Insensitive). So for example, you would use:
^(?i)CIALIS$
Not sure if the Content Filters can use RegEx but the Custom Rules in Smartermail certainly can.