A Double-Blind, Placebo-Controlled, Prophylaxis Study of Lamotrigine in Rapid-Cycling Bipolar Disorder

Background: Patients with rapid-cycling bipolardisorder are often treatment refractory. This study examinedlamotrigine as maintenance monotherapy for rapid-cycling bipolardisorder.

Method: Lamotrigine was added to patients’current psychotropic regimens and titrated to clinical effectduring an open-label treatment phase. Stabilized patients weretapered off other psychotropics and randomly assigned tolamotrigine or placebo monotherapy for 6 months. Time toadditional pharmacotherapy for emerging symptoms was the primaryoutcome measure. Secondary efficacy measures included survival instudy (time to any premature discontinuation), percentage ofpatients stable without relapse for 6 months, and changes in theGlobal Assessment Scale and Clinical Global Impressions-Severityscale. Safety was assessed from adverse event, physicalexamination, and laboratory data.

Results: 324 patients with rapid-cycling bipolardisorder (DSM-IV criteria) received open-label lamotrigine, and182 patients were randomly assigned to the double-blindmaintenance phase. The difference between the treatment groups intime to additional pharmacotherapy did not achieve statisticalsignificance in the overall efficacy population. However,survival in study was statistically different between thetreatment groups (p = .036). Analyses also indicated a 6-weekdifference in median survival time favoring lamotrigine.Forty-one percent of lamotrigine patients versus 26% of placebopatients (p = .03) were stable without relapse for 6 months ofmonotherapy. Lamotrigine was well tolerated; there were notreatment-related changes in laboratory parameters, vital signs,or body weight. No serious rashes occurred.

Conclusion: This was the largest and onlyprospective placebo-controlled study of rapid-cycling bipolardisorder patients to date; results indicate lamotriginemonotherapy is a useful treatment for some patients withrapid-cycling bipolar disorder.