Comparison of the pharmacokinetics and clinical efficacy of new extended-release formulations of methylphenidate

Introduction: Attention-deficit hyperactivity disorder (ADHD) is a common neurobehavioral disorder of which the main features are inattention, hyperactivity and impulsivity. Methylphenidate (MPH) is the mainstay of treatment, but its short duration of action and consequent need for multiple administrations has been problematic for children attending school. Extended-release (ER) formulations have been developed to help overcome the drawbacks associated with immediate-release (IR) preparations. Areas covered: This review focuses on the pharmacokinetics of ER MPH formulations (Concerta (R), Equasym XL (R)/Metadate CD (R), Medikinet Retard (R) and Ritalin LA (R)). It also attempts to align the properties of each agent with available clinical findings in children/adolescents with ADHD. Expert opinion: In the author's opinion, Concerta, Equasym XL/Metadate CD, Medikinet Retard and Ritalin LA offer the convenience of once-daily administration with absorption characteristics resembling two or three times daily dosing with IR MPH preparations. All formulations produce plasma concentrations necessary to maintain symptom control during school time in children with ADHD. However, their pharmacokinetic profiles differ with respect to peak plasma levels and the rate at which peak levels are attained and decline. These differences may provide physicians with the opportunity to prescribe a formulation best suited to the symptom profile of individual patients. Additional clinical research is required to clarify further the relative merits of these ER formulations with the goal of enabling