First, read the English article below.

Xanax is a type of sedative. It belongs in a class of drugs called benzodiazepines, which in turn are grouped under central nervous system depressants. The active ingredient in Xanax is Alprazolam, which essentially slows down your central nervous system, that is why it's considered a tranquilizer. It does this by binding to receptors in your brain, stimulating production of GABA. GABA is a naturally occuring neurotransmitter that reduces the activity of neurons to which it binds. Most often, Xanax is prescribed for anxiety. You may also have it prescribed for panic disorder, though sometimes doctors are reluctant to prescribe it for this condition, as you often get panic attacks when you are relaxed. Sometimes, it is used a sleep aid in a mild dosage.  Xanax can stop or lessen panic attacks. Xanax can get you through a crisis, such as a stressful exam or difficult meeting. The correct dosage will get your anxiety out of your way so you can focus properly. It treats the symptoms, not the cause. Xanax is not a cure for an anxiety disorder. Talk with your doctor about what treatments can help you in the long term. Xanax can become addictive over time. Therefore, this drug can be abused, and it has been a factor in many overdose cases. 

Now, please write a short abstract for it in Vietnamese. Abstract:
Biết thuốc Xanax là gì. Hiểu thuốc Xanax được kê đơn để làm gì. Biết vì sao bác sĩ có thể không muốn kê đơn thuốc Xanax.