Bipolar disorder is among the top causes of worldwide disability and is characterised by both depressive and manic episodes but the depressive symptoms are now recognised to be the predominant cause of disability in the long term. However, using conventional anti-depressants can run the risk of sending people into the manic phase of the illness. Recent guidelines have suggested a role for lamotrigine. There is good evidence for its long-term effectiveness in preventing relapse but the evidence for its effectiveness in the acute phase of bipolar depression is much more mixed. Researchers from Oxford University pooled the results from five separate studies with a total of 1,072 participants. They found consistent evidence that lamotrigine has a beneficial effect on depressive symptoms. The overall effect was modest although the advantage over placebo was larger in more severely-depressed participants.
Geddes, John R., Calabrese, Joseph R. and Goodwin, Guy M. - Lamotrigine for treatment of bipolar depression: independent meta-analysis and meta-regression of individual patient data from five randomised trials British Journal of Psychiatry January 2009, 194(1), 4-9