Levodopa minimum plasma concentration ( Cmin ) for each levodopa/carbidopa dose and for the mean of all levodopa/carbidopa doses increased substantially with all active treatments ( entacapone and opicapone ) when compared to the control group ( placebo ) , with values ranging from 1.7-fold ( 200 mg entacapone ) to 3.3-fold ( 75 mg opicapone ) .