The invention relates to a unit for the micronization of a solid active agent such as a salt preferably table salt (NaCI) for inhalation comprising a micronizer driven by a motor. The unit according to the invention is characterised in that micronization is performed by a unit constituted by a closed rotary drum (2) receiving a solid active agent having the same grain size preferably 0.1 4 mm as table salt (NaCI) where the wall surfaces of the micronizer unit are made at least in part of a material having a filtering capacity of 0.1 1000 µm the material preferably being a mesh like or microperforated material. A further unit according to the invention is characterised in that the micronizer consists of a rotary block (23) made of the active agent a friction block (24) adapted to be in frictioning relation with the rotary block and a clamping mechanism (25) adapted for holding the friction block (24) in position and for clamping the friction block (24) to the rotary block (23) the micronizer being disposed in a closed housing (11) and the wall surfaces of the housing (11) being at least in part made of a material having a filtering capacity of 0.1 1000 µm.
