Tamoxifen, a breast cancer drug which has been safely used for years, is being heralded for new treatments--specifically acute mania. Tamoxifen blocks estrogen receptors, and was initially thought to be helpful in women whose breast cancer had lots of estrogen receptors. However, it has recently been found to be beneficial to a large number of women whose breast cancer does not have estrogen receptors. This finding has lead to more in-depth exploration of Tamoxifen and its biochemical structure and effects.
Husseini Manji, MD, associate professor of psychiatry and behavioral neurosciences and director of the Neuropsychiatric Research Unit, has discovered that Tamoxifen can be particularly effective in treating the manic phase of bipolar disorder. Bipolar effective disorder is a common, severe, and debilitating mental illness, in which 15 percent of patients typically die from suicide. It is characterized by both depressive and manic episodes.
"Currently, two medications are approved by the FDA for the treatment of mania," said Dr. Manji. "Both lithium and valproate do work, but a major limitation is that they take days or even weeks to become effective. Patients are normally hospitalized and treated with sedative drugs while we wait for the lithium or valproate to work. This is not an ideal situation." In articles previously published in the Journal of Neurochemistry, Dr. Manji showed that both lithium and valproate, when used over a period of weeks, inhibit the activity of a family of chemicals called protein kinase C (PKC). Researchers have discovered that Tamoxifen is a potent PKC inhibitor.
"When I heard that news, I decided to do a study using Tamoxifen in the treatment of mania," noted Dr. Manji. "So far, we’ve treated seven patients and six of them have responded positively. In some cases, when we’ve gone up in dose fairly quickly, the response has been evident within two-three days. Particularly interesting is that five out of five male patients have responded." .