The effects of oral d-amphetamine on impulsivity in smoked and intranasal cocaine users.

backgroundEffective treatments for cocaine use disorders remain elusive. Two factors that may be related to treatment failures are route of cocaine used and impulsivity. Smoked cocaine users are more likely to have poorer treatment outcomes compared to intranasal cocaine users. Further, cocaine users are impulsive and impulsivity is associated with poor treatment outcomes. While stimulants are used to treat Attention Deficit Hyperactivity Disorder (ADHD) and attenuate certain cocaine-related behaviors, few studies have comprehensively examined whether stimulants can reduce behavioral impulsivity in cocaine users, and none examined route of cocaine use as a factor.

methodsThe effects of immediate release oral d-amphetamine (AMPH) were examined in 34 cocaine users (13 intranasal, 21 smoked). Participants had three separate sessions where they were administered AMPH (0, 10, or 20mg) and completed behavioral measures of impulsivity and risk-taking and subjective measures of abuse liability.

resultsSmoked cocaine users were more impulsive on the Delayed Memory Task, the GoStop task and the Delay Discounting Task than intranasal cocaine users. Smoked cocaine users also reported more cocaine craving and negative mood than intranasal cocaine users. AMPH produced minimal increases on measures of abuse liability (e.g., Drug Liking).

conclusionsSmoked cocaine users were more impulsive than intranasal cocaine users on measures of impulsivity that had a delay component. Additionally, although AMPH failed to attenuate impulsive responding, there was minimal evidence of abuse liability in cocaine users. These preliminary findings need to be confirmed in larger samples that control for route and duration of cocaine use.