Allopurinol in Schizophrenia: A Randomized Trial Administering Allopurinol vs Placebo as add-on Antipsychotics in Patients With Schizophrenia

Inclusion Criteria: 1. Male or female, 18-65 years of age, inclusive 2. Because gout is relatively rare in women of childbearing age, there are few reports describing the use of allopurinol during pregnancy; in those there were no adverse fetal outcomes attributable to allopurinol. Therefore, only females who are abstinent or practicing an established method of birth control (oral contraceptive tablets, hormonal implant device, hormone patch, injectable contraceptive, intrauterine device \[IUD\]) can be included in the trial. 3. Willing and able to provide informed consent, after the nature of the study has been fully explained 4. Current DSM-IV-TR diagnosis of schizophrenia as confirmed by SCID 5. Symptoms: 4 (moderate) or above on CGI-S AND \>= 4 (moderate) score on two of the following four PANSS items: delusions, hallucinatory behaviors, conceptual disorganization or suspiciousness/ persecution. 6. Must be on any antipsychotic drug for at least 2 weeks prior to the baseline visit, at doses within the PORT criteria. Patients receiving higher doses will have their records reviewed to insure that dose is required. Patients receiving two anti-psychotics, or IM depot antipsychotics can also be included. 7. Inpatients or outpatients. Exclusion Criteria: 1. Unwilling or unable, in the opinion of the Investigator, to comply with study instructions 2. Pregnant or breast-feeding 3. Unstable medical disease (malignancy, poorly controlled diabetes, active ischemic cardiac disease, or cardiomyopathy, serious pulmonary disease, , kidney disease, impaired liver functioning 4. Likely allergy or sensitivity to allopurinol 5. At significant risk of committing suicide, or in the opinion of the Investigator, currently is at imminent risk of suicide or harming others. 6. Suffers from a significant Substance Dependence disorder based on DSM-IV criteria within the 3 months prior to Screening, or is deemed by the Investigator to have a high risk of substance use during the study. Patients with a history of recreational use of cannabinoids or alcohol, and/or patients who smoke cigarettes can be included. 7. Concurrent delirium, mental retardation, drug-induced psychosis, or history of brain trauma.