A 9 year old child with a history of ADHD diagnosed at 5 years of age has presented to you with multiple tics in different pas of the body. The child had also developed vocal tics including barking sounds and coprolalic. There is history of similar illness in the family. Note that the child has never had any pharmacotherapeutic agents for ADHD. Which of the following drugs will you consider in the treatment of the child initially?