College of Pharmacy
Methylphenidate is the most commonly prescribed medication for the treatment of attention deficit hyperactivity disorder (ADHD), and is metabolized by the highly polymorphic carboxylesterase 1 (CES1) enzyme to the inactive ritalinic acid metabolite. Variants within the CES1 gene have been shown to reduce its enzymatic activity, thus resulting in higher than expected methylphenidate concentrations at standard dosing. This has the potential to increase the variation seen in both clinical response and the frequency of adverse events. The primary objective of this retrospective study was to determine associations between clinical response to methylphenidate and frequency of adverse effects with variation in the CES1 gene in children 6-16 years of age.