Alprazolam, also known under the trade names Xanax and Niravam, is a short-acting drug of the benzodiazepine class used to treat moderate to severe anxiety disorders, panic attacks, and as an adjunctive treatment for anxiety associated with major depression. It is also available in an extended release form, Xanax XR. Both forms are now available generically.

http://en.wikipedia.org/wiki/Xanax

Xanax (alprazolam) is prescribed for generalized anxiety disorder (GAD) and panic disorder. Generalized anxiety disorder is characterized by 6 months or more of chronic, exaggerated worry and tension that is unfounded or much more severe than the normal anxiety most people experience. People with GAD usually expect the worst. They worry excessively about money, health, family, or work, even when there are no signs of trouble. They are unable to relax and often suffer from insomnia. Sometimes the source of the worry is hard to pinpoint. Simply the thought of getting through the day provokes anxiety.

http://www.rxlist.com/cgi/generic/alpraz.htm