Single- and multiple-dose pharmacokinetics of an oral once-a-day osmotic controlled-release OROS (methylphenidate...

Methylphenidate is used for the treatment of attention deficit hyperactivity disorder (ADHD). OROS (methylphenidate HCl) is an osmotic controlled-release delivery system designed for once-daily oral dosing. The pharmacokinetics of OROS (methylphenidate HCl) 18 mg qd, sustained-release (SR) methylphenidate 20 mg qd, and the immediate-release (IR) formulation given as three 5 mg doses every 4 hours (tid) were compared in adults. In addition, the single- and multiple-dose pharmacokinetics of the OROS formulation were studied. Following OROS (methylphenidate HCl), there was a gradual increase in the mean methylphenidate plasma concentrations with peak concentrations noted at 6 to 8 hours. With the SR formulation, peak plasma concentrations were noted at approximately 4 hours. Following the IR regimen, methylphenidate plasma concentrations fluctuated in tandem with oral dosing; peak concentrations were noted at 6.5 hours. The terminal half-life of methylphenidate was similar for the three formulations. The dose-normalized methylphenidate Cmax for OROS (methylphenidate HCl) was significantly lower than for IR and SR methylphenidate. The bioavailability of methylphenidate and PPA from OROS (methylphenidate HCl) relative to the IR and SR formulations was complete. Mean methylphenidate AUC and terminal half-life were similar after single (32.9 ng.h/mL and 3.9 hours) and multiple doses (35.2 ng.h/mL and 3.9 hours) of OROS (methylphenidate HCl).