Crank by Ellen Hopkins.
Written in verse, 15-year-old narrator Kristina reveals how she became addicted to crank, and how the stimulant turned her from straight-A student to drug addict.

On a visit to see her long-absent dad, she meets a boy who introduces her to crank. At first she finds it freeing, but soon Kristina’s personality disappears inside the drug. What began as a wild, ecstatic ride turns into a struggle through hell for her mind, her soul, and her life.