The purpose of this study was to evaluate the relative bioavailability and safety of a multilayer extended-release bead methylphenidate ( MPH ) hydrochloride 80mg ( MPH-MLR ) capsule or sprinkles ( 37 % immediate-release [ IR ] ) versus MPH hydrochloride IR ( Ritalin ( ) ) tablets , and to develop a pharmacokinetic ( PK ) model simulating MPH concentration-time data for different MPH-MLR dosage strengths .