Abstract: The present invention relates to a method for treatments relating to bipolar disorder in a mammal, including a human, the treatments including treatment of rapid-cycling bipolar disorder, treatment of symptoms of bipolar disorder selected from the group consisting of acute mania and depression, treatment for effecting mood stabilization; treatment for preventing relapse into bipolar episodes, and for the treatment of suicidal thoughts and tendencies associated with bipolar disorder, comprising administering to said mammal an effective amount of a compound of the formula I: or a pharmaceutically acceptable acid addition salt thereof, wherein Ar, n, X, and Y are as defined.