Patients were treated in a randomized , open-labeled , parallel group clinical trial with either a combination of salmeterol xinafoate/fluticasone propionate ( SF ; Seretide , GlaxoSmithKline ) Diskus ( 50/500 g twice daily ) or ipratropium bromide/salbutamol ( IS ; Combivent , Boehringer Ingelheim ) MDI ( 42 g/240 g quartic daily ) for 12 weeks .