Conditions: Anxiety Disorders
Keywords: Generalized Anxiety Disorder Chronic Mediation Treatment Double-Blind Placebo Controlled Venlafaxine XR Relapse
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 268
Healthy volunteers: no

Brief summary:
This study will assess the effectiveness of venlafaxine XR, randomized to either venlafaxine XR or placebo in preventing the relapse of generalized anxiety disorder after 6 months of treatment versus 12 months of treatment.

Detailed description:
Generalized anxiety disorder (GAD) is a highly prevalent, chronic psychiatric disorder. Despite the fact that GAD frequently demands prolonged treatment with medication, very little is known about the benefits of long-term treatment. GAD is characterized by 6 months or more of exaggerated worry and tension that is unfounded or much more severe than the normal anxiety most people experience. People with GAD are unable to relax and often suffer from insomnia. Venlafaxine XR, a drug used to treat depression, has been shown to be effective in the short-term treatment of GAD. However, its benefits over a course of more than 8 weeks have not been assessed. This study will evaluate the effectiveness of venlafaxine XR in treating GAD on a long-term basis and preventing the relapse of GAD after 6 months of treatment versus 12 months of treatment.

Participants in this double-blind study will first receive 6 months of open-label treatment with venlafaxine XR. Upon completion of this initial phase, participants will be randomly assigned to either continue on venlafaxine XR or begin taking placebo. After 12 months, participants taking venlafaxine XR will be randomly assigned to continue on the drug or switch to placebo. Participants will have 22 study visits over at least 18 months. Follow-up visits will occur 24 months after enrollment. Relapse of GAD will be assessed with the Hamilton Anxiety Scale and Global Severity and Improvement Scale. A variety of methods, including questionnaires and standardized scales, will be used to assess secondary outcomes.

Arms:
arm 1: 6-month randomized phase of Venlafaxine XR at a flexible dose of 75 - 225 mg/d arm 2: 6-month randomized, double-blind phase of Venlafaxine XR at a flexible dose of 75 - 225 mg/d occurring between months 6 - 12 of the study arm 3: 6-month randomized, double blind phase of placebo occurring between months 6 - 12 of the study arm 4: 6-month randomized, double blind phase of Venlafaxine XR at a flexible dose of 75 - 225 mg/d occurring between months 13 - 19 of the study arm 5: 6-month randomized, double blind phase of placebo occurring between months 13 - 19 of the study arm 6: 6-month randomized, double blind phase of placebo occurring between months 13 - 19 of the study

Interventions: intervention 1: Venlafaxine XR intervention 2: Placebo
Intervention descriptions: intervention 1: Six month intervention of Venlafaxine XR treatment with flexible range of 75 to 225 mg/d intervention 2: six month intervention with placebo drug

Protocol document: