My first concern is what kind of evaluations did the pediatrician use to diagnosis ADHD? Other disorders such as anxiety and depression mimic ADHD behavior.
Here's some info I found: http://www.apa.org/topics/adhd/index.aspx
It doesn't really seem to address the medications question you have, but it has some info on ADHD treatment.
Someone, I think Sheila, posted an article a while back on the proper way to diagnosis ADHD. I'll see if I can find it.
