Five different amphetamine-based pharmaceuticals are currently used in ADHD treatment: racemic amphetamine, dextroamphetamine, lisdexamfetamine, and two mixed enantiomer products (Adderall and Dyanavel XR). Lisdexamfetamine is an inactive prodrug of dextroamphetamine (i.e., lisdexamfetamine itself doesn't do anything in the body, but it metabolizes into dextroamphetamine). Adderall is a proprietary mixture of (75%) dextroamphetamine and (25%) levoamphetamine salts, which results in very mild differences between their effects. Dyanavel XR contains a similar mixture. Adderall begins to work before dextroamphetamine because of levoamphetamine. Levoamphetamine also provides Adderall with a longer clinical effect than dextroamphetamine. Some children with ADHD and comorbid disorders respond well to levoamphetamine.