Carbamazepine is a potential
treatment option for bipolar depression,
as evident by studies dating
back to 1980.11 However, most
data support its use during manic
episodes and in the prevention of
episodic mood swings. In contrast, a
recent meta-analysis of 4 relatively
small studies showed that when used
as monotherapy, valproic acid was
superior to placebo in the treatment
of depressive symptoms.12 The
use of these medications must also
be weighed against their potential for
interactions with other medications.
Carbamazepine is a potent inducer
of the 3A4 enzyme of the hepatic
cytochrome p450 system, leading
to faster clearance and lower serum
concentrations of medications
metabolized through this pathway.
In contrast, valproic acid has been
shown to be a potent inhibitor of
lamotrigine elimination, leading to
elevated serum concentrations of
lamotrigine when used in combination.
Overall, further studies are
warranted before definitive conclusions
can be made regarding the role
of lamotrigine, carbamazepine, and
valproic acid in treating acute episodes
of bipolar depression.