An extended-release capsule formulation. of carbamazepine is approved for use in adult patients experiencing an acute manic or mixed episode associated with bipolar I disorder. A capsule of extended-release carbamazepine contains three types of bead: immediate release, extended release and enteric release, constituting 25%, 40% and 35% of the dose, respectively. Extended-release carbamazepine capsules 200-1600 mg/day demonstrated superior antimanic efficacy to placebo in two 3-week, well designed trials in adult patients with bipolar I disorder and acute manic or mixed episodes. At study end, reductions from baseline in Young Mania Rating Scale scores were significantly greater with carbamazepine than with placebo (primary endpoint). The active treatment was effective from the end of the first week of treatment (post hoc analysis). A In the 3-week trials and a 6-month extension study, most treatment-emergent adverse events observed with extended-release carbamazepine were of mild or moderate severity. In the 3-week trials, although significantly greater reductions in white blood cell count occurred with extended-release carbamazepine than with placebo, only one case of leukopenia was deemed serious. There were no reports of agranulocytosis or aplastic anaemia with up to 6 months' treatment.