Despite the increased use of methylphenidate(Drug information on methylphenidate) in preschoolers with attention deficit/hyperactivity disorder (ADHD), few data are available regarding the efficacy and safety of methylphenidate in this population. Methylphenidate has been approved by the FDA for the treatment of ADHD in children aged 6 years or older. A recent large-scale, controlled trial of methylphenidate for the treatment of preschoolers with ADHD provides clinically relevant and greatly needed information for clinicians who treat these children.
The Preschool ADHD Treatment Study (PATS) was an NIMH-funded, 6-center, controlled trial to evaluate the efficacy and safety of methylphenidate for preschool children with ADHD. 1,2 The ages of children who participated in the study ranged from 3 to 5.5 years. One hundred eighty-three children participated in the study, which consisted of 4 phases: a 1-week, open-label, lead-in phase (n = 183); a 5-week, double-blind, placebo-controlled phase (n = 165); a 5-week, double-blind, parallel phase (n = 114); and a 10-month, open-label maintenance phase (n = 140). Methylphenidate immediate-release (IR) was administered on a thrice-daily schedule.
Overall, the results showed that compared with placebo, there was a sig- nificant decrease in children's ADHD symptoms with methylphenidate at dosages of 2.5 mg, 5 mg, and 7.5 mg tid. The effect sizes for these dosages ranged from 0.4 to 0.8. There were no significant differences found between placebo and methylphenidate at a dosage of 1.25 mg tid. The mean optimal methylphenidate-IR total daily dose was 14.2 mg (0.7 mg/kg).
Clinical Findings The researchers in the PATS reported a number of clinically important findings. 2-4 Dosing
Based on the data, it was suggested that initial treatment with methylphenidate begin at low dosages. The recommended starting dosage was methylpheni- date-IR at 2.5 mg bid, with an increase to 7.5 mg tid over 1 week.
Safety
The 5 most commonly reported adverse effects were emotional outbursts, difficulty in falling asleep, repetitive behavior/thoughts, decreased appetite, and irritability. One serious adverse event of a seizure was rated by the treating physician as possibly being associated with methylphenidate treatment. Eleven percent of preschoolers who received methylphenidate discontinued study treatment because of adverse events. Emotionality and irritability were frequent reasons for discontinuation.
Discontinuation of methylphenidate treatment because of intolerable adverse effects occurred in more preschool-aged children (11%) in the PATS than in school-aged children (fewer than 1%) in the Multimodal Treatment Study of Children With ADHD. 5
For some preschoolers, the irritability and emotionality diminished over time. The investigators found that adverse effects such as appetite reduction and difficulty in sleeping remained stable. They recommended that these side effects be managed by dose reduction, by the child eating breakfast before receiving medication, and by parents giving healthy snacks to the child before bedtime.
