"Antidepressant" is a general description of several classes of drugs, which, as the name implies, are designed to combat depression.
These drugs have also been found to be useful in dealing with the depressive phase of bipolar disorder, however antidepressants are NOT commonly prescribed to people with documented bipolar disease. They are typically prescribed to people when their bipolar disorder is not known and they are experiencing a depressive phase.
There can be complications with antidepressants with bipolar patients because the antidepressants change the brain chemistry and can shoot a person into the mania stage.
Where Antidepressants Fit In
Antidepressants are usually coupled with mood stabilizing drugs that are more useful against mania. When used this way, both the highs and lows of bipolar disorder can be more easily managed. On the whole, drugs are considered an essential part of the management of bipolar disorder.
How Do Antidepressants Work
Antidepressants are occasionally prescribed in conjunction with mood stabilizers when used to treat bipolar disorder. The mood stabilizers tend to be more effective in handling the manic phase of the disorder, and can also help minimize the possibility of certain side effects.