The effects of different methylphenidate (MPH) delivery profiles on driving performance of 6 male ADHD adolescents, aged 16 to 19 years, were evaluated by a randomized, crossover, single-blind study comparing controlled-release (OROS) MPH (Concerta) given q.d. to immediate-release MPH (Ritalin) in equal doses t.i.d. in a study at the University of Virginia, Charlottesville, VA. A computer-quantified Impaired Driving Score (IDS) was used to measure driving performance tested on a driving simulator at 2 PM, 5 PM, 8 PM, and 11 PM after treatments had been maintained for 7 days. In participants receiving MPH t.i.d. the IDS worsened in the evening (8 PM) compared to those on OROS MPH q.d. (p=.01). Performance was significantly better overall when on once daily Concerta compared to MPH given t.i.d. (p=.004). 
COMMENT. Adolescent drivers with ADHD when treated with Concerta q.d. demonstrated less variability and performed significantly better throughout the day than when treated with immediate release MPH t.i.d. During the MPH t.i.d. treatment regimen driving performance deteriorated significantly by 8 PM., a time when adolescents are likely to be driving. Concerta-treated adolescents were less likely to brake inappropriately on the open road, their driving was less erratic, and they were less likely to run stop signals. The participants unblinded self-appraisals correlated significantly with the objective measures of driving performance on the simulator. ADHD is not only a school-based disorder, impacting behavior and learning, but also predisposes to accidental injuries related to bicycles and motor vehicles. Treatment benefits with the various formulations of MPH, amphetamines, and Strattera should consider the impact on risk of serious accidents in addition to school performance.
Extended release methylphenidate (MPH) formulations in ADHD. Once-daily doses of Metadate CD (MCD) and Concerta (CON) produced statistically different effects on measures of behavior and performance in children with ADHD as measured in a laboratory school setting (The Comacs Study)  The formulation with the highest expected plasma MPH concentration had the most benefits at any point in time. MCD was superior in the morning, MCD and CON were equivalent in efficacy during the afternoon, and CON was superior in the early evening.