A process for the preparation of a dry powder formulation for use in a dry powder inhaler, said formulation comprising: a) a fraction of fine particles consisting of a mixture of 90 to 99.5 percent by weight of micronized particles of a physiologically acceptable excipient and 0.5 to 10 percent by weight of magnesium stearate, b) a fraction of coarse particles consisting of a physiologically acceptable excipient having a mass median diameter equal to or higher than 175 micron, wherein the ratio between said fine particles a) and said coarse particles b) is from 1:99 and 30:70 percent by weight; c) a combination of micronized particles of glycopyrronium bromide, beclometasone dipropionate, and formoterol fumarate dihydrate as active ingredients, whereby the at least 90% of all said micronized particles of the active ingredients have a volume diameter lower than 6.0 micron, their volume median diameter is comprised between 1.2 and 2.5 micron, no more of than 10% of their volume diameter is lower than 0.6 micron, said particles being further characterized by a span expressed as [d (v, 0.9) - d(v,0.1)]/d(v,0.5) comprised between 1.0 and 4.5; said process comprising the steps of: i) pre-selecting the excipient particles and additive particles of fraction a) with a particle size wherein at least 90% of all said particles have a volume diameter lower than 12 micron, their volume median diameter is comprised between 3 to 7 micron, and no more than 10% of said particles have a diameter lower than 1.5 micron; ii) preparing the fraction of fine particles a), by co-mixing the excipient particles and the additive particles in a high-energy apparatus for a period of less than 20 minutes at a speed of rotation comprised between 500 and 4000 r.p.m.; iii) mixing said fraction of fine particles a), said fraction of coarse particles b), and all the micronized active ingredients; whereby magnesium stearate coats the surface of the excipient particles a) in such a way as that the extent of surface coating is higher than 20%. a) a fraction of fine particles consisting of a mixture of 90 to 99.5 percent by weight of micronized particles of a physiologically acceptable excipient and 0.5 to 10 percent by weight of magnesium stearate, b) a fraction of coarse particles consisting of a physiologically acceptable excipient having a mass median diameter equal to or higher than 175 micron, wherein the ratio between said fine particles a) and said coarse particles b) is from 1:99 and 30:70 percent by weight; c) a combination of micronized particles of glycopyrronium bromide, beclometasone dipropionate, and formoterol fumarate dihydrate as active ingredients, whereby the at least 90% of all said micronized particles of the active ingredients have a volume diameter lower than 6.0 micron, their volume median diameter is comprised between 1.2 and 2.5 micron, no more of than 10% of their volume diameter is lower than 0.6 micron, said particles being further characterized by a span expressed as [d (v, 0.9) - d(v,0.1)]/d(v,0.5) comprised between 1.0 and 4.5; i) pre-selecting the excipient particles and additive particles of fraction a) with a particle size wherein at least 90% of all said particles have a volume diameter lower than 12 micron, their volume median diameter is comprised between 3 to 7 micron, and no more than 10% of said particles have a diameter lower than 1.5 micron; ii) preparing the fraction of fine particles a), by co-mixing the excipient particles and the additive particles in a high-energy apparatus for a period of less than 20 minutes at a speed of rotation comprised between 500 and 4000 r.p.m.; iii) mixing said fraction of fine particles a), said fraction of coarse particles b), and all the micronized active ingredients;