Pharmacotherapy of bipolar II disorder: a critical review of current evidence

Objectives: There is much controversy surrounding the diagnosis and treatment of patients with bipolar II disorder (BP II). To address the growing need to find effective treatment strategies for patients with BP II, this article identifies and summarizes available published evidence specific to the pharmacotherapy of BP II. Methods: Using the keywords, 'bipolar disorder', 'type II' or 'type 2', 'bipolar II', 'hypomania', and 'bipolar spectrum', a search of the databases Medline (via PubMed), the Cochrane Central Register of Controlled Trials (via Ovid), and PsychInfo was conducted for the period January 1994 to January 2003. Articles deemed directly relevant to the treatment of BP II were selected. Studies that included both BP I and II patients were excluded if results for BP II patients were not analyzed and reported separately. Results: Fourteen articles were selected for the review period. There are no double blind, randomized controlled trials (RCT) involving only BP II patients. Most studies investigating the pharmacotherapy of BP II are methodologically limited, having observational or retrospective designs and small samples. For long-term treatment, lamotrigine has the strongest quality of evidence (double blind RCT), while lithium is the best studied. With regard to short-term treatment, there is some limited support for the use of risperidone in hypomania, and for divalproex, fluoxetine and venlafaxine in treating depression. Conclusions: There is a paucity of sound evidence to help guide clinicians treating BP II patients. Decisions about pharmacotherapy should be made on a case-by-case basis; overall, broad recommendations that are based on available evidence cannot be adequately made. More quality research is needed to delineate effective treatment strategies.