Generalized anxiety is a common disorder with an estimated lifetime prevalence of 5.1 percent. It usually begins in the early 20s and has a low rate of spontaneous remission. The popular view of this disorder is that it is mild, but studies have shown that it can cause substantial interference in the lives of affected patients. Many patients seek professional help that usually results in the use of medication to treat the symptoms. Many medications have been used to treat generalized anxiety disorder, but each has safety limitations or limited research indicating effectiveness. Venlafaxine affects the serotonergic and noradrenergic pathways and may have some anxiolytic properties. Rickels and colleagues studied the safety and efficacy of extended-release venlafaxine in the treatment of generalized anxiety disorder without concomitant major depressive disorder.

The study was a multicenter, randomized, placebo-controlled trial using outpatients with generalized anxiety disorder. To be included in the study, the patients had to score 18 or higher on the Hamilton Rating Scale for Anxiety and score 2 or more on its anxious mood and tension factors. Patients were excluded if they had a concomitant major depressive disorder within six months of the study or a current diagnosis based on the screening interview. Patients were randomly assigned to receive placebo or extended-release venlafaxine in a dosage of 75, 150 or 225 mg per day for up to eight weeks. Primary efficacy variables included total and psychic anxiety factor scores on the Hamilton anxiety scale, and severity and global improvement scores on the Clinical Global Impression scale at the end of the study. Safety evaluation was based on patients' reports of adverse events, routine physical examinations, laboratory evaluations and electrocardiography.

Patients who received extended-released venlafaxine scored better on all four of the primary measurements when compared with the placebo group. In addition, they scored better on the Clinical Global Impression scale than those who received placebo. Patients responded well to three doses of venlafaxine, with the 225-mg-per-day dosage providing the best response. The most common adverse events reported in the venlafaxine group included nausea, insomnia, dry mouth, somnolence, dizziness and asthenia. These symptoms tended to be mild, to occur early in the treatment course and to subside with continued treatment.

The authors conclude that extended-release venlafaxine is a safe and effective alternative for the treatment of generalized anxiety disorder in patients without concomitant major depressive disorder. All dosages of venlafaxine were effective, but 225 mg per day provided the best results. The majority of the side effects of the medication were mild and subsided with time.