MONDAY, March 3, 2008 (HealthDay News) -- A drug commonly used to treat breast cancer may one day help manage symptoms of mania, or the "high" phase experienced by people with bipolar disorder, researchers say.
Men and women who took tamoxifen for three weeks experienced a significant lessening of their mania compared to people taking a placebo, the study found.
Whether or not tamoxifen will become a mainstay of treatment for bipolar disorder remains to be seen, however.
"The bad news is [that] this is something we would have to figure out how side effects are going to be a factor in long-term use," said one expert, Dr. Jane Ripperger-Suhler, assistant professor of psychiatry and behavioral science at Texas A&M Health Science Center College of Medicine and a psychiatrist with Scott & White Mental Health Center. "The good news is that people are thinking outside the box in terms of what might be effective for a particular disorder."
"More trials need to be conducted," added Dr. Ma-Li Wong, professor of psychiatry and vice chair for translational research at the University of Miami Miller School of Medicine. "Tamoxifen is not a drug that is without side effects. One needs to be careful in terms of drawing conclusions. Bipolar is not a short-term disorder and in clinical trials for breast cancer, you're talking about treatment of five years. Also, the dose used in this study is a bit high in comparison to that used in breast cancer."
The findings, by researchers at Dokuz Eylül University Medical School in Izmir, Turkey, are published in the March issue of Archives of General Psychiatry.
Tamoxifen helps suppress breast cancer by interfering with the action of the female hormone estrogen in the body.
The drug also inhibits the activity of a family of enzymes known as protein kinase C (PKC). Activity of PKC may be altered during the mania state of bipolar disorder, experts say. Existing drugs for the condition, including librium and valproate sodium, inhibit PKC-associated signaling in the brain.
Previous animal studies as well as pilot trials in humans have suggested that tamoxifen might be effective in treating bipolar-related mania.
For the new study, 66 men and women with bipolar disorder and currently in a manic state, or mixed states that included mania, were randomly assigned to take 40 to 80 milligrams of tamoxifen a day or a placebo for up to three weeks.
Participants were also given up to 5 milligrams a day of the sedative lorazepam as needed.
Fifty patients completed the study.
At the end of three weeks, participants taking tamoxifen had significantly lower scores on tests used to measure the severity of mania, with 48 percent of them citing a reduction of at least half in their mania scores.
Those in the placebo group had slightly increased mania scores, and only 5 percent experienced a reduction of at least half in their mania scores.
Twenty-eight percent of those in the tamoxifen group reached the cut-off scores for remission from mania, compared to none in the placebo group, the researchers said.
Another expert was intrigued by the results.
"I found the study very interesting -- not that it necessarily indicates that tamoxifen is the best, newest, greatest drug for bipolar, although that's possible," said Dr. Andrew Kolodny, vice chair of psychiatry at Maimonides Medical Center in New York City. He said the study's real importance may lie in the fact that "it points towards a mechanism for the disease. The particular role of a molecule is hard to find in psychiatry."
The U.S. National Institute of Mental Health has more on bipolar disorder.