The present invention relates to drug formulations in dry powder form for administration by inhalation and indicated for the treatment of obstructive airway syndromes such as asthma and chronic obstructive pulmonary disease (COPD). In particular, the invention relates to an inhalable pharmaceutical composition comprising a first powder consisting of budesonide, or one of its pharmaceutically allowable salts, in a quantity greater than 5% w/w of said first powder, leucine in a quantity in the range of 5 to 70% w/w of said first powder, and lactose in a quantity in the range of 20 to 90% w/w of said first powder； a second powder consisting of formoterol, or one of its pharmaceutically allowable salts, in a quantity greater than 1% w/w of said second powder, leucine in a quantity in the range of 5 to 70% w/w of said second powder, and lactose in a quantity in the range of 20 to 90% w/w of said second powder； and a third powder consisting of leucine in a quantity in the range of 5 to 70% w/w of said third powder, and lactose in a quantity in the range of 20 to 90% w/w of said third powder. Said composition has a fine particle fraction (FPF) greater than 60% and a delivered fraction (DF) greater than 90%.La presente invención se refiere a formulaciones farmacológicas en forma de polvo seco para la administración por inhalación e indicadas para el tratamiento de síndromes respiratorios obstructivos como el asma y enfermedad pulmonar obstructiva crónica (COPD)； en particular, la invención se refiere a una composición farmacéutica inhalable que comprende un primer polvo de budesonida, o una de sus sales farmacéuticamente admisibles, en una cantidad mayor que 5% p/p de dicho primer polvo, leucina en una cantidad en el intervalo de 5 a 70% p/p de dicho primer polvo y lactosa en una cantidad en el intervalo de 20 a 90% p/p de dicho primer polvo； un segundo polvo que consta de formoterol o una de sus sales farmacéuticamente admisibles, en una cantidad mayor de 1% p/p de dicho s
