THURSDAY, Feb. 23 (HealthDay News) -- Antidepressant treatment of patients with bipolar disorder is associated with a high risk of threshold switches to full-duration hypomania or mania, with venlafaxine having the highest risk among antidepressants tested, according to a study in the February issue of the American Journal of Psychiatry.
Gabriele S. Leverich, M.S.W., of the National Institute of Mental Health in Bethesda, Md., and colleagues examined 159 patients with bipolar I or II disorder who participated in 228 acute (10-week) trials of bupropion, sertraline, or venlafaxine. Patients in 87 of the trials continued therapy for up to one year.
In the acute trials, threshold switches into full-duration hypomania occurred in 11.4 percent of patients and threshold switch to mania in 7.9 percent. For the continuation trials, threshold switches into full-duration hypomania and mania occurred in 21.8 percent and 14.9 percent of patients, respectively.
The rate of threshold switches to sub-threshold brief hypomanias was higher in the acute and continuation trials for venlafaxine (3.60 and 3.75, respectively), compared with bupropion (0.85 and 1.17, respectively) and sertraline (1.67 and 1.66, respectively).
"Adjunctive treatment with antidepressants in bipolar depression was associated with substantial risks of threshold switches to full-duration hypomania or mania in both acute and long-term continuation treatment," the authors write, noting that venlafaxine had the highest relative risk and bupropion had the lowest.
Drugs for the study were provided by GlaxoSmithKline, Pfizer and Wyeth.
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