The invention relates to an apparatus for nebulizing preferably powdered medicinal formulations, the nebulization being assisted by propellant. According to the invention, the propellant is supplied in pulsed form to the powder cavity (1) containing the formulation, which is attached to the nozzle (3) from which the aerosol is emitted. The apparatus according to the invention provides an increase in the fraction of pulmonary particles in the aerosol leaving the nozzle (3).