Although the cause of the death of Whitney Houston can not be known for weeks, the singer of 48 years would have had a prescription for Xanax and history of alcohol and drug rehabilitation in at least three times during his career. Found dead Feb. 11 in the bathtub of the general theory is used to cause her death was an overdose of a combination of drugs and alcohol. Toxology reports can take weeks to complete, but we know that the combination of Xanax and alcohol can be deadly, said Dr. Marvin Seppala, chief medical officer of Hazelden, a treatment center for dependence on alcohol and other advanced drugs. Anxiolytic alprazolam, the generic name of Xanax, classified as a benzodiazepine. Benzodiazepines are sedative drugs that act by binding to a portion of the brain for its soothing, or gamma amino butyric acid to enhance the natural ability to calm down. They work quickly, often within 15 minutes - and highly addictive. The effect lasts only a few hours. Alprazolam is also the eighth most prescribed drug in the United States in 2010, according to The New York Times. "It is often used for stage fright or other types of anxiety, but was abused a lot and have the potential of the addiction," said Seppala, especially if someone has a genetic predisposition to addiction. "Tolerance develops quickly if used regularly."