Amphetamine and dextroamphetamine combination is used to treat attention-deficit hyperactivity disorder (ADHD) and narcolepsy (uncontrollable desire for sleep or sudden attacks of deep sleep).These two medicines belong to the group of medicines called central nervous system (CNS) stimulants.mphetamine and dextroamphetamine combination is used to treat attention-deficit hyperactivity disorder (ADHD) and narcolepsy (uncontrollable desire for sleep or sudden attacks of deep sleep).