Pharmacokinetics [edit]. According to a medication of pamphlet of Adderall XRÂ®, the mean elimination half-life for d-AMP is 10 hours in adults; 11 hours in persons less than or equal to 165 lbs and 9 hours in children 6-12 years of age.s stated above, Adderall is a prescription medication used to treat many forms of ADHD (increased or more difficulty focusing, controlling actions, and remaining still or quiet than other people who are the same age) and narcolepsy (a sleep disorder that causes excessive daytime sleepiness and sudden attacks of sleep).