The objective of the study is to evaluate the efficacy of allopurinol, compared to placebo, as add-on to mood stabilizers and/or antipsychotic in the treatment of patients with bipolar disorder, in a manic episode.

An emerging body of evidence supports a role for dysfunctional purinergic related neurotransmission in mood disorders [1, 2]. Adenosine agonists have been shown to have properties similar to those of dopamine antagonists and there is a well characterized antagonistic interaction between adenosine and dopamine receptors in the ventral striatum. Increased adenosynergic transmission has been demonstrated to reduce the affinity of dopamine agonists for dopamine receptors. It has been theorized that adenosine may exert some of its antipsychotic effects through modulation of glutamatergic transmission.

Two double-blind, randomized, add-on, placebo-controlled trials comparing allopurinol and placebo in acute mania have showed statistically significant greater improvements in YMRS scores in the allopurinol vs. placebo groups. These empiric data, together with the theoretical and basic science background cited, provide the impetus for this proposed study.

Inclusion Criteria:

1. Male or female, 18-65 years of age, inclusive
2. 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 bipolar I disorder with the current episode manic (296.4x) or mixed (296.6x), as confirmed by the Modified Structured Clinical Interview for DSM-IV (SCID). In order to ensure that this is an acute manic episode, we will verify that the current manic episode was preceded by a period of euthymia or depression. If inpatients, subjects will be included only up to 14 days after admission. Subjects with psychotic features will be included in the study.
5. YMRS> 17
6. Patients receiving one or multiple mood stabilizers, and/or one or more anti-psychotics.
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. Currently taking any of the following medications: warfarin, amoxicilline, ampicilline, theophylline, or mycophenolate mofetil.
5. Likely allergy or sensitivity to Allopurinol
6. At significant risk of committing suicide, or in the opinion of the Investigator, currently is at imminent risk of suicide or harming others.
7. 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.
8. Concurrent delirium, mental retardation, drug-induced psychosis, or history of brain trauma.