I just happened to read an article about stimulants to treat adult ADHD because my husband has it. They were talking about the range of different medications, but what I took away from it was that there really is no average dosage based on height and weight like there is with many drugs.
It said that aside from the obvious tolerance from previous use of these drugs that there's a big genetic disposition as to why some people need a much higher dose than others.
Other than reading that article I have very limited first hand knowledge and one 20mg has me going and cleaning house. Looking around here...Maybe I should order some?