Pregabalin in the Treatment of Patients With Generalized Anxiety Disorder (GAD).

• Efficacy will be measured by the improvement in the total Hamilton Anxiety Rating Scale (HAM-A) scores from baseline observed following 8 weeks of double-blind treatment or at earlier termination during the double-blind treatment phase
• and analyzed using a mixed linear model for repeated measures.

• Change in HAM-A Total Score at Weekly Visits [ Time Frame: Baseline, Weeks 1 through Week 8 ] [ Designated as safety issue: No ]
• Number of Responders Using Hamilton Anxiety Rating Scale (HAM-A) [ Time Frame: Weeks 1 through Week 8 ] [ Designated as safety issue: No ]
• Subjects in Remission Using Hamilton Anxiety Rating Scale (HAM-A) Total Score [ Time Frame: Week 1 through Week 8 ] [ Designated as safety issue: No ]
• Time to Onset of Sustained Hamilton Anxiety Rating Scale (HAM-A) Improvement [ Time Frame: Week 8 ] [ Designated as safety issue: No ]
• Number of Responders Using Clinical Global Impression of Improvement (CGI-I) Score [ Time Frame: Week 1 through Week 8 ] [ Designated as safety issue: No ]
• Clinical Global Impression of Severity (CGI-S) Score [ Time Frame: Week 8 ] [ Designated as safety issue: No ]
• Change in Hamilton Depression Rating Scale (HAM-D) Total Score [ Time Frame: Weeks 1 through Week 8 ] [ Designated as safety issue: No ]

• HAM-A changes from baseline by week
• HAM-A responders (greater than/equal to 50% decrease in total HAM-A scores from baseline through Week 8)
• Time to onset of sustained HAM-A improvement (greater than/equal to 50% reduction in HAM-A score from baseline)
• HAM-A Psychic Anxiety and Somatic subscale changes
• Remission rate (HAM-A less than/equal to 7) in subjects at last study week
• Hamilton Depression Rating Scale score change from baseline through week 8
• Sheehan Disability Scale (SDS) total and domain scale change from baseline
• Changes in the Daily Diary and Daily Assessment of Symptoms-Anxiety (DAS-A) and Global Anxiety-Visual Analogue Scale (GA-VAS) component and total scores from baseline
• CGI-S at the subject's last study week
• CGI-I responders (CGI-I greater than/equal to 2, much improved or very much improved) at the subject's last study week.

The primary objective of this study is to evaluate the efficacy of pregabalin as compared to placebo in the treatment of patients with general anxiety disorder (GAD). Efficacy will be measured by the improvement in the total Hamilton Anxiety Rating Scale (HAM-A) scores from baseline observed following 8 weeks of double-blind treatment or at earlier termination during the double-blind treatment phase and analyzed using a mixed linear model for repeated measures.

Further enrollment in this study was stopped on January 28, 2008 based on the recommendation of an independent data monitoring committee. The recommendation to stop the study was not based on any safety findings.

• Drug: pregabalin
  pregabalin 150-600 mg/day flexibly dosed for the first 6 weeks and fixed dosed for the last 2 weeks of total 8 weeks of double blind study period, + concurrent GAD treatment from the open-label study period
  Other Name: Lyrica
• Drug: placebo
  placebo + concurrent GAD treatment from the open-label study period

• Placebo Comparator: Arm 2
  Intervention: Drug: placebo
• Experimental: Arm 1
  Intervention: Drug: pregabalin

Inclusion Criteria:

• Adult male and female subjects with primary DSM-IV diagnosis of GAD, as confirmed by the MINI structured interview.
• Historical failure to respond optimally to a GAD treatment

Exclusion Criteria:

• Current primary DSM-IV (Diagnostic and Statistical Manual of Mental Disorders 4th edition) diagnosis of major depressive disorder with or without seasonal pattern, dysthmic disorder, depressive disorder NOS (not otherwise specified), social phobia, panic disorder with or without agoraphobia, post traumatic stress disorder, dissociative disorder, borderline personality disorder, obsessive-compulsive disorder, antisocial personality disorder, as defined in the DSM-IV TR (Diagnostic and Statistical Manual of Mental Disorders 4th edition, Text Revision).
• Past and/or current DSM-IV diagnosis of schizophrenia, schizoaffective disorder, other psychotic disorders, bipolar disorders (I or II), factitious disorder or cognitive disorder (including delirium, dementia, and amnestic disorder).