The primary outcome measure is the PANSS total score at week 9. Subjects will be classified as responders if the improvement in PANSS total score is 20% or greater, and the proportion of responders in each group will be determined. Complementary outcome measures will be the CGI severity score, CGI improvement score, and SOFAS score. Safety and tolerance will be assessed by reports of adverse events and clinically significant changes in vital signs, weight, waist circumference, extrapyramidal side effects, metabolic and hematological measures.