- Current treatment of at least 3 months with risperidone.
- Primary diagnosis of schizophrenia.
- Total Positive and Negative Symptoms Scale (PANSS) score baseline.
- Psychiatric diagnosis other than schizophrenia as assessed by the modified Mini
International Neuropsychiatric Interview (MINI) and considered by the investigator to
be the primary psychiatric diagnosis.
- History or presence of clinically significant cardiovascular, endocrine, hepatic,
renal or other medical disease that might be detrimental to the subject or confound
- History of any suicide attempt within 3 years of day 1 or significant immediate risk
of violence or suicidality.