Discovery may lead to new drug to treat manic phase of the illness, study says
WEDNESDAY, Sept. 12 (HealthDay News) -- The breast cancer drug tamoxifen helps control the manic phase of bipolar disorder, and works faster than many standard medications used to treat the chronic mental illness, a new study has found.
"One of the problems with existing treatments for bipolar disorder is they seem to have this long period before they start to work," explained Dr. Husseini K. Manji, senior study author and director of the U.S. National Institute of Mental Health's mood and anxiety disorders program.
Current treatments sometimes take weeks to become effective, Manji said. "And that obviously creates a huge problem," he said. When patients are in the manic phase, particularly, not getting relief fast enough from medication may mean they need to be hospitalized, he noted.
For the study, Manji and his colleagues gave eight patients experiencing a manic episode tamoxifen, while another eight received a placebo; no one knew which drug they were getting. After three weeks, 63 percent of those on tamoxifen had reduced symptoms of mania, compared to just 13 percent of those on a placebo. The tamoxifen group responded by the fifth day of treatment.
The study results are published online in the September issue of Bipolar Disorders.
Manji and his colleagues decided to study tamoxifen because they knew that standard medications used to treat mania are known to lower the activity of an enzyme called protein kinase C, or PKC, that regulates activities in brain cells. This enzyme is believed to become overactive when bipolar disorder patients experience a manic episode.
Tamoxifen also blocks PKC, but does it more directly than some bipolar drugs, according to the researchers.
Manji and his team made the discovery after years of searching for the correct cellular target to treat bipolar diso
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