Two 3-week multicentre , double-blind , randomised , placebo-controlled studies in acute mania ( study BIA-2093-203 : dose titrated by response , ESL 600-1800mg or 800-2400mg , once-daily ; study BIA-2093-204 : fixed doses of 600 , 1200 and 1800mg , once-daily ) were followed by a recurrence prevention study consisting of a 2-week open-label period ( 900mg , once-daily ) continued by a double-blind , parallel-group , fixed dose ( 300 , 900 and 1800mg , once-daily ) period for a minimum of 6 months .