Study Evaluating Vabicaserin in Subjects With Schizophrenia

• Drug: vabicaserin
  
  This study will utilize a randomized, double-blind, placebo-controlled, comparator-referenced, multicenter, parallel-group adaptive design with placebo, risperidone (4 mg/day), and up to 7 treatment arms of vabicaserin (50, 100, 150, 200, 300, 400 and 600 mg/day) over the course of the study
• Drug: risperidone
• Other: placebo

• Experimental: 1
  
  Intervention: Drug: vabicaserin
• Active Comparator: 2
  
  4mg/day
  Intervention: Drug: risperidone
• Placebo Comparator: 3
  
  matching placebo
  Intervention: Other: placebo

Inclusion Criteria:

• Generally healthy, men and women, aged 18 to 65.
• Hospitalization because of an acute exacerbation of schizophrenia with a diagnosis of schizophrenia established greater than 1 year.
• Ability to remain hospitalized for the duration of the screening period and for 4 weeks of double-blind treatment.

Exclusion Criteria:

• Current Axis I primary psychiatric diagnosis other than schizophrenia (DSM-IV-TR criteria).
• Current diagnosis or history of substance abuse or dependence (DSM-IV-TR criteria), including alcohol (except for nicotine), within 3 months before baseline (day -1).
• Subjects taking high or chronic doses of benzodiazepine at the screening evaluation who, in the investigator's judgment, would be likely to have severe withdrawal symptoms upon discontinuation.