In this @-week , double-blind , active-controlled study , patients aged @-@ years with a previous inadequate response to MPH were randomized ( @:@ ) to dose-optimized LDX ( @ , @ or @ mg/day ) or ATX ( patients < @ kg : @-@ @ mg/kg/day , not to exceed @ mg/kg/day ; patients @ kg : @ , @ or @ mg/day ) .