Examination of Tamoxifen in Acute Mania in Patients With Bipolar I Disorder

The purpose of this study is to examine how the drug tamoxifen affects the brain in patients with bipolar I disorder. Bipolar Disorder (BD) is a severe, chronic, and often life-threatening illness for which safe and effective treatments are necessary. The mood stabilizing effects of lithium and valproate have revolutionized the treatment of patients with BD. However, a significant percentage of patients do not respond fully to these drugs, and the biochemical basis for the antimanic and mood-stabilizing actions of lithium and valproate is unclear. Both drugs inhibit protein kinase C (PKC). There is a need to investigate the efficacy of a direct PKC inhibitor in the treatment of acute mania. Tamoxifen is currently the only relatively selective PKC inhibitor available for human use. Participants in this study will be screened with a physical, psychiatric, and eye examination and blood and urine tests. Eligible participants will be hospitalized at the Clinical Center for at least 4 weeks. They will be tapered off all psychiatric medication and kept drug free for 2 to 7 days. They will also be put on a low-monoamine, low-caffeine diet. Participants will be randomly assigned to receive either tamoxifen or placebo (an inactive pill) for 3 weeks. During this time, participants will have daily pulse and blood pressure measurements, several electrocardiograms (EKGs), and blood draws. Weight measurements will be taken at least twice during the study, and caffeine or dextromethorphan will be given at the beginning and end of the study to test how tamoxifen affects the way the body eliminates other medications. Participants will have a physical examination at the end of the study. At the end of this 4-week study, some participants may continue the study and will receive tamoxifen for an additional 3 weeks. At the conclusion of the study, participants' psychiatric status will be reassessed and long-term psychiatric treatment for their mood disorders will be arranged.