Inclusion Criteria:

• The subject has a current primary diagnosis of schizophrenia or schizoaffective disorder; specifically, an acute exacerbation with prominent "active phase" symptoms, as described in DSM-IV-TR criteria (and confirmed by the SCID I/P). Subjects with schizophrenia may belong to any of the following subtypes: paranoid, disorganized, catatonic, or undifferentiated
• The subject has a PANSS total score of >= 60
• The subject has a score of >= 4 ("moderate") on at least 2 out of the following 5 PANSS positive symptoms: delusions, conceptual disorganization, hallucinatory behavior, grandiosity, suspiciousness/persecution
• The subject is male or female of non-childbearing potential (i.e., surgically sterilized or postmenopausal). Females of childbearing potential may participate in the study only if they meet all of the following: a) a negative pregnancy test (b hCG) at Screening; b) they must agree not to attempt to become pregnant during the course of the study; and c) if sexually active, they must agree to use a combination of two acceptable contraceptive methods for the duration of the study (e.g., hormonal, intra-uterine device, condom, diaphragm with a spermicide). Males that are not surgically sterile (vasectomy) may participate in the study only if a) sexually inactive, or b) agrees to use a barrier method of birth control (condom) for the duration of the study.
• The subject is between 18 and 65 years old inclusive at the time of randomization
• The subject has a reliable caregiver (if applicable) or an identified responsible person (e.g., family member, social worker, nurse) who will support him/her to ensure compliance with treatment and outpatient visits. In addition, the subject must have an adequate place of residence
• The subject agrees to be hospitalized for the duration of the Taper off/Washout Period and at least the first fourteen days of the Double-blind Period

Exclusion Criteria:

• The subject has any condition that is likely to interfere with his/her ability to complete the study and all the study-related procedures (e.g., blindness, deafness, language difficulties, sensory or motor deficits)
• The subject has any condition which is likely to interfere significantly with the absorption, distribution, metabolism or excretion of the active treatment, including: malabsorption syndromes, previous GI surgery, active peptic ulcer disease, chronic GI disease etc.; evidence suggesting impaired kidney function (e.g., raised urea or creatinine with albuminuria or hematuria); any condition affecting plasma proteins (e.g., multiple myeloma, chronic medical illness)
• The subject has a diagnosis of one or more of the following conditions: another primary Axis I disorder, including schizophreniform disorder, bipolar disorder or major depressive disorder; comorbid Axis II diagnoses, including borderline personality disorder and mental retardation. (Note: a diagnosis of depression NOS (not otherwise specified) is acceptable for inclusion into the study)
• The subject has a diagnosis of substance or alcohol disorder (abuse/dependence according to DSM-IV-TR criteria), excluding nicotine, within one (1) month prior to the beginning of the Screening Period, or in the opinion of the investigator, a disorder that will interfere with the conduct of the study
• The subject has a history of substance-induced psychotic disorder in the previous 6 months
• The subject has evidence suggestive of treatment-resistant schizophrenia (i.e., lack of significant clinical improvement despite adequate courses and doses of at least two different antipsychotic medications during the previous 2 years; or adequate use of clozapine indicated for treatment-resistant schizophrenia).
• The subject has serious violent, homicidal or suicidal ideation in the opinion of the investigator
• The subject has a Screening QTc interval of > 430 msec if male and > 450 msec if female
• The subject has clinically significant abnormal laboratory values at Screening
• The subject's LFTs (AST, ALT or total bilirubin levels) are not within normal limits at screening
• The subject has a diagnosis, history, or a positive serological result suggestive of liver disease including but not limited to hepatitis and Gilbert's Syndrome
• The subject has a positive urine drug screen for non-prescribed drugs of abuse including but not limited to alcohol, cocaine, phencyclidine (PCP), opiates, barbiturates, tetrahydrocannabinol (THC), or amphetamines at any point prior to randomization
• The subject has received any of the following treatments within the time periods described: mood stabilizers or antidepressants during the 30 days prior to Screening; electroconvulsive therapy during the 3 months prior to Screening; clozapine during 60 days prior to Screening.
• The subject is currently receiving treatment with oral psychotropic medications or has received depot neuroleptics within one inter-injection interval