SIDE-EFFECTS OF METHYLPHENIDATE AND DEXAMPHETAMINE IN CHILDREN WITH ATTENTION-DEFICIT HYPERACTIVITY DISORDER - A DOUBLE-BLIND, CROSSOVER TRIAL

Objective. To compare the side effect profiles of methylphenidate (MPH ) and dexamphetamine (DEX) in children with attention deficit hyperact ivity disorder (ADHD), as well as to determine which symptoms are genu ine adverse effects of stimulant medication, as opposed to aspects of the child's underlying behavioral phenotype. Design. Double-blind, cro ssover study. Setting. Pediatric teaching hospital ambulatory behavior clinic. Subjects. A total of 125 children with ADHD with a mean age o f 104.8 months. Interventions. Subjects received DEX (0.15 mg/kg/dose) and MPH (0.3 mg/kg/dose) twice a day for 2 weeks each in a randomized order. Outcome Measures. The Barkley Side Effects Rating Scale (17 sy mptoms; 0 = absent, severity rated from 1 to 9) was completed by paren ts at baseline and at the completion of each trial fortnight. Results. Subjects' parents reported a significantly greater mean number (8.19) and mean severity (4.08) of ''side effects'' before commencing the tr ial than during the MPH period (number 7.19; severity 3.24), but not t he DEX period (number 7.64, severity 3.73). The mean severity (but not mean number) was greater on DEX than on MPH. DEX caused more severe i nsomnia and appetite suppression compared with the baseline rating. Ap petite suppression was the only item rated more severe on MPH than at baseline. Six side effects were significantly more severe on DEX than MPH: insomnia, irritability, proneness to crying, anxiousness, sadness /unhappiness, and nightmares. None were more severe on MPH than DEX. O verall, both MPH and DEX were well tolerated by most subjects, with on ly four subjects discontinuing the trial period because of severe adve rse effects (2 [1.6%] on each stimulant). Conclusions. Many symptoms c ommonly attributed to stimulant medication are actually preexisting ch aracteristics of children with ADHD and improve with stimulant treatme nt. At the doses investigated, both DEX and MPH caused appetite suppre ssion, and DEX caused insomnia. Negative emotional symptoms were more severe on DEX than MPH.