Branded Concerta has
A unique delivery system with a methylphenidate
" overcoat" for an immediate release dose + 2 " push compartments" that deliver the rest of the dose over the school day as intestinal fluids enter the insoluble capsule.
Onset of action is 1 hour, peak action ~6 hrs., duration ~'12 hours. There is very litlle " rebound" as it wears off. Dosing starts low & is titrated for optimal effect