The drug is nicknamed "dex", but is commonly known as Dextroamphetamine or Dexedrine. It's a stimulant that prescribed to patients who have ADHD, but some Canadian college students have begun using it to help them cram for finals.
"One first-year U of C business student told a Calgary TV station that he buys Dexedrine for $5 a pill from a friend with ADHD. He said dex keeps him extra-focused for hours of hard-core studying and also while he's writing exams."
One of the dangers of misusing Dexedrine is that is can aggravate existing medical conditions like high blood pressure, and there is a risk of psychological addiction.