Extended-release carbamazepine for acute bipolar mania: a review

In December 2004, an extended-release capsule formulation of carbamazepine was approved by the U.S. Food and Drug Administration for the treatment of acute manic or mixed episodes associated with bipolar I disorder. This formulation allows twice-daily dosing and minimizes plasma carbamazepine fluctuations. The efficacy, safety and tolerability of the product were demonstrated with two pivotal randomized, placebo-controlled, double-blind monotherapy trials. These studies showed efficacy in bipolar I mania in patients with acute manic or mixed episodes. Pooled post hoc analyses documented a significant onset of effect within seven days, an incremental response of about 25% over placebo and a moderate effect size of 0.61 with no treatment-emergent depression. Carbamazepine's mode of action in mania is unknown, but a variety of effects on receptors, neurotransmitters, ion channels and binding sites have been documented. It has a complex pharmacokinetic profile due to autoinduction and a long-acting active metabolite. Carbamazepine's most frequent adverse events comprise dizziness, somnolence, nausea and vomiting, although these tend to diminish over time. It is effectively weight neutral and can provide an acceptable and efficacious treatment option for bipolar I mania.