Stimulants have been shown to be very effective in the treatment of Attention Deficit Hyperactivity Disorder (ADHD). [1] Studies have shown that full day treatment is often preferable to shorter treatment [2] and recent guidelines advise full day treatment. [3] However, there are many barriers to giving multiple doses of short acting medicine. New delivery systems have evolved to overcome tachyphylaxis and provide effective long-acting treatment with a single pill. [4] One of the new formulations is the spheroidal oral drug absorption system (SODAS). SODAS consists of capsules with two types of beads in a 1 to 1 ratio. One type of bead provides immediate release methylphenidate (IR MPH), and the other type of bead consists of MPH coated with a polymer that delays release for 4 hours. SODAS MPH has been shown to be effective in clinical studies [5]. However, the mechanism of action remains unclear. While pharmacokinetic studies have shown a double pulse profile in the serum [4], the central nervous system pharmacokinetics are unknown. Understanding the central nervous system pharmacokinetic properties is critical for new drug development for ADHD, especially for drugs of different lengths of action.