If you take any medications on a regular basis, make sure you put about a weeks worth in your kit. All the food and water in your kit isn't going to do any good if you can't survive without specific medications. When I used to take my "crazy" meds I made sure I had at least 3 days worth in my pack. A disaster is not a good time to see how you would do weaning off of it:)
I know it can be difficult with prescriptions to get extra. I remember my insurance wouldn't let me get a new bottle until I was almost out of the last one. Maybe talk to your doctor about gettign some samples-that way they are in teh convenient packaging as well.
Now I keep medications like ibruprofen, tylenol for the kids, their excema cream, prenatal vitamins (since I am usually pregnant or nursing:). They are a great vitamin even if you aren't of course. You will not be eating as much or getting as much nutrients during a disaster most likely, so make sure you have vitamins for the whole family. I just bought a container of chewable animal vitamins at the dollar store for the kids.