Antipsychotic and Motor Effects of ACP-103 When Administered in Combination With Haloperidol and Risperidone

The primary purpose of this study is to determine whether a combination of ACP-103 (the study medication) with either haloperidol or risperidone will show antipsychotic efficacy and that it is safe and well tolerated. Further purposes of this study are to determine whether ACP-103, in combination with either haloperidol or risperidone, will enhance their antipsychotic effectiveness, demonstrate effectiveness against the negative symptoms, improve motoric tolerability, and is safe and well tolerated. This is a seven-week study (one week screening and six weeks of study medication) where a total of 400 patients who meet entrance criteria will randomly be assigned to receive one of five groups of study treatments of either low dose haloperidol plus ACP-103, low dose haloperidol plus placebo (a substance similar to a sugar pill), low dose risperidone plus ACP-103, low dose risperidone plus placebo, or high dose risperidone plus placebo. The study will begin with with a three to seven day drug-free period followed by six weeks of a stable daily dosage of study medication. Study subjects will be treated as hospital in-patients during screening and for the first 14 days of the study. Study subjects will be closely monitored throughout the study.