Anxiety disorders are prevalent and associated with increased morbidity and 
mortality. Some chronic anxiety disorders, including generalized anxiety 
disorder (GAD), may be characterized by an underlying high level of anxiety on 
which exacerbations of symptoms are superimposed. Effective treatment of anxiety 
disorders should therefore strive to attain both an acute reduction in the 
symptoms of anxiety (a response) and sustained resolution of the symptoms of any 
underlying chronic anxiety (remission). This strategy may necessitate long-term 
treatment of these disorders by pharmacotherapy and/or psychotherapy. Studies 
using the serotonin and norepinephrine reuptake inhibitor (SNRI), venlafaxine 
extended release (XR), suggest that these aims may be achieved using this newer 
class of drugs. Studies with venlafaxine XR in patients with GAD have 
demonstrated robust anxiolytic efficacy over placebo, particularly regarding 
worry, cognitive dysfunction, and muscular tension, which are specific to GAD. 
Administration of venlafaxine XR over both short- (8-week) and long-term 
(6-month) periods resulted in a significantly greater number of patients 
achieving response and remission than obtained with placebo. Long-term treatment 
with venlafaxine XR in patients with GAD showed greater efficacy than that 
observed in short-term studies. This was achieved without any loss of short-term 
efficacy and patients' social functioning was also restored. While available 
data indicate that venlafaxine XR is an appropriate choice of agent in the 
long-term treatment of GAD, more studies are needed to determine how to further 
increase remission rates and to maintain remission beyond 6 months.