Ebselen as an add-on Treatment in Hypo/Mania

Ebselen, a new drug for mania Bipolar disorder, formerly known as manic depression, is a condition that affects mood, which can swing from one extreme to another. Typically, there will be periods of: * Depression - very low mood and energy levels * Mania or hypomania (less severe) - very high mood and overactive energy levels A drug called lithium, used to stabilise mood, is an important treatment for bipolar disorder but has a number of problematic side effects, is not well tolerated by patients and requires careful monitoring. To replace lithium with other, safer medicines would have clear advantages. The investigators are interested in an antioxidant medicine(substance that may prevent or delay cell damage) called ebselen which has been shown to work in a similar way as lithium and the investigators are investigating whether it might help improve recovery from manic episodes. The present study aims to see whether ebselen, used as an 'add-on' treatment can help stabilise mood in patients experiencing high mood (hypo/mania). Sixty patients experiencing hypo/mania will be given in a randomised order (similar to tossing a coin) either ebselen or placebo (dummy) in addition to their usual medication for three weeks after which the add-on treatment will be stopped. A final follow up visit will take place one week after the study medication has been stopped. Participants can be in or outpatients and mood will be monitored with questionnaires and interviews. Activity will also be monitored with the use of an actiwatch (similar to a wrist watch) which will be worn continuously throughout the study. A single blood sample will be optional and occur after the first week of treatment to check plasma levels of ebselen and inflammatory markers. A positive outcome in this trial will be followed by longer term studies of ebselen in bipolar disorder.