I've read that for the amphetamines, a higher dose extends the duration of the medication effects than a lower dose does.

But that that is not true for Ritalin. For Ritalin, you could take 10 mg and it is going to wear off in 2-4 hours, or 100 mg and it'll wear off in 2-4 hours.

I wonder why this is. I understand the huge difference in half-lives between amphetamines and Ritalin, but that doesn't seem to explain it.

Anyone know anything?