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Effectiveness of Long-Term Versus Short-Term Treatment of Generalized Anxiety Disorder With Venlafaxine XR

This study has been completed.
Information provided by:
National Institute of Mental Health (NIMH) Identifier:
First received: September 12, 2005
Last updated: October 12, 2010
Last verified: September 2008
This study will assess the effectiveness of venlafaxine XR in preventing the relapse of generalized anxiety disorder after 6 months of treatment versus 12 months of treatment.

Condition Intervention Phase
Anxiety Disorders
Drug: Venlafaxine XR
Drug: Placebo
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Short-term Versus Long-term Treatment in Generalized Anxiety Disorder

Resource links provided by NLM:

Further study details as provided by National Institute of Mental Health (NIMH):

Primary Outcome Measures:
  • Relapse of GAD [ Time Frame: Meausured at Months 6, 12, and 24 ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Anxiety, depression, and GAD symptoms [ Time Frame: Measured at Months 6, 12, 18, and 24 ] [ Designated as safety issue: No ]

Enrollment: 330
Study Start Date: January 2004
Study Completion Date: September 2009
Primary Completion Date: September 2009 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1
Drug: Venlafaxine XR
All participants will take venlafaxine for 6 months. After this initial 6 months, participants who are not randomized to placebo will continue to take venlafaxine.
Experimental: 2
Venlafaxine and placebo
Drug: Venlafaxine XR
All participants will take venlafaxine for 6 months. After this initial 6 months, participants who are not randomized to placebo will continue to take venlafaxine.
Drug: Placebo
After initial treatment with venlafaxine, some participants will be randomized to take placebo for 6 months in the second phase of the study and then to switch back to venlafaxine or continue with placebo for an additional 6 months.

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.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • GAD diagnosis by structured interview
  • Hamilton Anxiety Scale score of 18 or MORE
  • Clinical Global Impressions Severity Scale score of at least 4
  • Hamilton Depression Scale score of 18 or less
  • Hamilton Depression Scale suicide item score less than 2
  • Use of an effective form of contraception throughout the study

Exclusion Criteria:

  • Hypersensitivity to venlafaxine XR
  • History of seizures
  • Episode of major depressive disorder in the previous 6 months
  • History of any psychotic illness, bipolar disorder, or dementia
  • Substance abuse and dependence during the past 6 months
  • Other anxiety disorders with the exception of social phobia as long as GAD is primary
  • Regular use of anxiolytics or antidepressants within 7 days of study onset
  • Use of fluoxetine or monoamine oxidase inhibitors within 28 days of study onset (low dose usage of benzodiazepines will not prevent participation)
  • Use of other psychotropic medication besides benzodiazepines during the study
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00183274

United States, Pennsylvania
University of Pennsylvania, 3535 Market Street, Suite 670
Philadelphia, Pennsylvania, United States, 19104-3309
Sponsors and Collaborators
National Institute of Mental Health (NIMH)
Principal Investigator: Karl Rickels, MD University of Pennsylvania
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):

Responsible Party: Karl Rickels, MD, University of Pennsylvania Identifier: NCT00183274     History of Changes
Other Study ID Numbers: R01MH065963  DSIR 83-ATAS 
Study First Received: September 12, 2005
Last Updated: October 12, 2010
Health Authority: United States: Federal Government

Keywords provided by National Institute of Mental Health (NIMH):
Generalized Anxiety Disorder
Chronic Mediation Treatment
Placebo Controlled
Venlafaxine XR

Additional relevant MeSH terms:
Anxiety Disorders
Pathologic Processes
Mental Disorders
Venlafaxine Hydrochloride
Serotonin and Noradrenaline Reuptake Inhibitors
Neurotransmitter Uptake Inhibitors
Membrane Transport Modulators
Molecular Mechanisms of Pharmacological Action
Neurotransmitter Agents
Physiological Effects of Drugs
Antidepressive Agents, Second-Generation
Antidepressive Agents
Psychotropic Drugs processed this record on October 21, 2016