Of course, it does depend if you took the extended
release version or not. Essentially, if you look at the label, the
time it gives between doses plus half again should be a pretty good indicator that most of it is out of your system.
Note, under interactions, it says "Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially: ... other stimulants (e.g.