The term mood stabilizer is widely used to describe drugs such as lithium (Eskalith CR, Lithobid), valproate (Depacon, Depakene, Depakote), carbamazepine (Equetro, Tegretol) and lamotrigine (Lamictal), which are used to treat the mania and depression of bipolar disorder. No real definition exists, however. The FDA does not officially recognize the term and the medical community has not yet arrived at a consensus about how to define it.
The problem is that the perfect mood stabilizer -- a drug that treats and prevents both the highs and lows of bipolar disorder -- does not actually exist. The drugs currently being called mood stabilizers are generally best at treating only one pole of the illness, most often mania.
One proposed definition, which seems to fit how the term is actually being used, is to define mood stabilizers as drugs that decrease the frequency or severity of any type of episode in bipolar disorder and do not worsen the frequency or severity of other types of episodes. Others, however, have a proposed a more stringent definition, which seeks to only label those drugs which treat and prevent both depression and mania as mood stabilizers.
Source:
Bauer, Mark S. and Michener, Landis. "What Is a 'Mood Stabilizer'? An Evidence-Based Response." American Journal of Psychiatry 161 (2004): 3-18.
