She has taken this drug for 10 years, and says it was prescribed by a doctor. The drug was not on the banned list until the rules changed Jan 1.
http://www.freep.com/story/sports/tennis/2016/03/08/nike-tag-heuer-suspend-ties-sharapova/81469616/
http://www.freep.com/story/sports/tennis/2016/03/08/nike-tag-heuer-suspend-ties-sharapova/81469616/