I don't know, but there is this nutritional supplement that will help you a lot with your anxiety. I've had severe anxiety for about 4 years now, and i've tried all the medications out there, if you really want to fix or cure your anxiety then i propose that you take it. I've taken it for the past 3 years, it really helps. The first few weeks i didn't notice a difference, but my family noticed a difference in my behavior the day i took it. It's called True Hope it's a pretty good nutritional supplement. Instead of having anxiety attacks 3-6 times a day i only have maybe one anxiety attack the entire year, and only because i forgot to take a days worth of my pills. here's the website http://www.truehope.com/default.aspx
People with mental disorders are generally deprived of the vitamin B in their brain, check out the testimonials and what not. good luck
Most people with anxiety find Ativan very helpful, it is less addictive than Xanax but takes longer to work, approximately 1 to 2 hours, they don't prescribe Xanax in the Uk.