Methylphenidate oral dose plasma concentrations and behavioral response in children

The relationship between methylphenidate (MP) oral dose and plasma concentration to social and cognitive behaviors was studied in 25 boys diagnosed as having attention deficit disorder with hyperactivity. Children were administered successive 1-week treatment conditions under the following schedule of fixed oral doses given twice daily: placebo; 0.25 mg/kg; 0.50 mg/kg; 1.0 mg/kg; placebo. Teacher and parent ratings showed increased improvement in social behavior as a function of MP dose. No drug effects were obtained on cognitive performance. MP plasma concentrations were significantly associated with oral dose and with measures of social behavior. No relationship was found with cognitive behavior. Side effects at the largest dose were severe enough to require discontinuation of treatment for five children, but were relatively mild for the remaining children.