Capsules effective in treating acute manic and mixed episodes of Bipolar I Disorder

11/15/05

Six month study data also announced at major medical meeting

Shire Pharmaceuticals Inc. has announced that University of North Carolina at Chapel Hill researchers studied the efficacy of carbamazepine extended-release capsules (CBZ-ERC, Equetro) in patients with manic or mixed episodes of Bipolar I Disorder over six months. Data from this open label study was presented by UNC researchers last week at the 18th annual U.S. Psychiatric and Mental Health Congress in Las Vegas.

These data complement a pooled analysis of data from two, three-week placebo-controlled phase 3 studies of CBZ-ERC, which demonstrated that CBZ-ERC significantly reduced manic and mixed symptoms for patients and was generally well tolerated. CBZ-ERC, manufactured for Shire US Inc., is the only formulation of carbamazepine approved by the U.S. Food and Drug Administration for treatment of patients with acute manic and mixed episodes associated with Bipolar I Disorder. Shire provided funding for these studies.

“Many patients still fail to find an effective medication for their bipolar disorder that is generally well tolerated with a low incidence of weight gain, which can influence their ability to stay on treatment,” said Richard H. Weisler, M.D., primary investigator of both clinical trials and adjunct professor of psychiatry at UNC’s School of Medicine. “A medication like CBZ-ERC that works effectively and is well tolerated in both manic and mixed patients is a very important addition to our treatment options for patients and their doctors.”

Weisler also is an adjunct assistant professor of psychiatry and behavioral sciences at Duke University Medical Center and has a private practice in Raleigh.

As many as 450 million people suffer from a mental or behavioral disorder worldwide, according to the World Health Organization. A recent study demonstrated that Bipolar I Disorder is more prevalent in the U.S. than previously estimated, affecting approximately 2 percent of the population annually and 3.3 percent of the population in its lifetime. These estimates are conservative considering the difficulty in the diagnosis of bipolar disorder. In the United States, annual costs for prevalence-based bipolar disorder are estimated at $45.2 billion, while lifetime costs of incidence-based bipolar disorder amount to about $24 billion. Bipolar disorder, also known as manic depression, is an illness that causes a person to experience extreme mood changes that alternate between manic episodes of abnormally high energy and the severe lows of depression, often with periods of normal mood in between.

The six-month study was an open-label extension trial for 92 patients who previously participated in one of two large, three-week phase 3 studies in which investigators randomized a total of 263 hospitalized participants to receive either CBZ-ERC or a placebo, although neither investigators nor patients knew to which group a patient was assigned until the study ended.

Of the patients who had responded to CBZ-ERC treatment during the phase 3 trials, defined as a 50 percent decrease in scores of the Young Mania Rating Scale (YMRS), 78 percent remained responders in the extension study. Also, 73 percent of those previously on placebo responded during the extension study. Overall, only 11 (14.3 percent) of the 77 intent-to-treat study patients experienced a relapse while taking CBZ-ERC. These participants’ estimated average time to relapse was 141.8 ± 5.6 days.

Weisler and his coinvestigators also pooled and analyzed the data from the two earlier phase 3 studies, confirming previous findings that CBZ-ERC is effective and generally well tolerated in patients with Bipolar I Disorder with manic or mixed episodes.

When examining the 147 patients experiencing mixed episodes, the investigators found that CBZ-ERC treatment demonstrated significantly greater improvements in average YMRS scores compared to placebo (-12.39 versus –8.84, P<.01). Patients experiencing manic episodes taking CBZ-ERC also had significantly greater improvements in average YMRS scores versus the placebo group (–12.22 versus –5.02, P<.0001).

All of the patients, who ranged in age from 18 to 76 years, had a previous diagnosis of Bipolar I Disorder, with the most current episode manic or mixed, as defined in the Diagnostic and Statistical Manual for Mental Disorders, fourth edition, text revision (DSM-IV-TR®).

Treatment with CBZ-ERC was initiated at 200 milligrams (mg) twice daily and increased, as necessary and tolerated, by 200 mg per day up to 1,600 mg per day. Doses greater than 1,600 mg per day were not studied.

The most common adverse events reported in these studies associated with CBZ-ERC included dizziness, somnolence, nausea, vomiting, ataxia and pruritis. These events were generally mild and were most often reported early in dose titration. Adverse events in all studies were typical of those associated with CBZ.

Weisler’s co-authors for both studies were Dr. R. Hirschfeld of the University of Texas Medical Branch at Galveston, Dr. A. J. Cutler of the University of South Florida, Dr. T. Gazda of St. Luke’s Medical Center, Dr. T. Ketter of Stanford University School of Medicine; Dr. P Keck, Jr. of the University of Cincinnati College of Medicine, Cincinnati, Ohio; Dr. A. Swann of the University of Texas Medical School at Houston; and Dr. A. Kalali of Quintiles CNS Therapeutics in San Diego.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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