Concentrated suspension of water insoluble pharmaceutical substances, comprising:a) micronized particles of at least one water insoluble pharmaceutical substance with a particle size distribution in which the d(0.5) fraction is less than 3 µm, the span value is less than 2, and such features are retained upon aging the suspension for 90 days said pharmaceutical substance being present at a concentration of from 5 to 50 times the concentration of a suspension of the same substance for inhalatory administrationb) an aqueous solution of a pharmaceutically acceptable surfactant as dispersing medium for said micronized particles of pharmaceutical substancec) a salt dissolved in said aqueous solution, at a concentration that: i) does not cause coagulation of said particles of pharmaceutical substance and ii) generates upon dilution an inhalatory suspension in which the concentration of salt in the aqueous phase is not higher than 10 g/l. present at a concentration of from 0.1 to 2.0 g/l.
