| Therapeutic Doses of Oral Methylphenidate Significantly Increase Extracellular Dopamine in the (2008) | |||||||||||||
Abstract | |||||||||||||
| Methylphenidate (Ritalin) is the most commonly prescribed psychoactive drug in children for the treatment of attention deficit hyperactivity disorder (ADHD), yet the mechanisms responsible for its therapeutic effects are poorly understood. Whereas methylphenidate blocks the dopamine transporter (main mechanism for removal of extracellular dopamine), it is unclear whether at doses used therapeutically it significantly changes extracellular dopamine (DA) concentration. Here we used positron emission tomography and [ 11 C]raclopride (D2 receptor radioligand that competes with endogenous DA for binding to the receptor) to evaluate whether oral methylphenidate changes extracellular DA in the human brain in 11 healthy controls. We showed that oral methylphenidate (average dose 0.8 � 0.11 mg/kg) significantly increased extracellular DA in brain, as evidenced by a significant reduction in B max/K d (measure | |||||||||||||
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