Pharmacokinetics of methylphenidate transdermal system (MTS): results from a laboratory classroom study.

Objective: To evaluate the pharmacokinetic properties of the methylphenidate transdermal system (MTS) in pediatric patients diagnosed with ADHD (attention-deficit/hyperactivity disorder) in a laboratory school setting.

Method: A phase II, randomized, double-blind, placebo-controlled, laboratory classroom study was conducted with prior dose optimization. Children (aged 6-12 years) with ADHD were titrated over 5 weeks to an optimal clinical MTS dose (10, 15, 20, or 30 mg/9 h). Participants were randomized to 1 week of either MTS or corresponding placebo, followed by crossover to the alternate treatment. Laboratory school evaluations, including pharmacokinetic blood sampling, occurred at the end of each treatment.

Results: MTS delivered d- and l-MPH (methylphenidate) into the systemic circulation throughout the 9-hour wear time, and plasma concentrations declined rapidly after patch removal. Over the time-course of clinical effectiveness (2-12 h), mean plasma concentrations of d-MPH at the most frequently titrated doses (15 and 20 mg/9 h) ranged from 4.97 to 28.3 ng/mL. Systemic exposure increased approximately dose proportionately. Plasma concentrations of the l-MPH were approximately one-half to two-thirds those for d-MPH.

Conclusions: Plasma concentrations of the much less active l-MPH were consistently lower than those of d-MPH. The clinical relevance of the MTS pharmacokinetic profile is discussed.