Stabilized preparations for use in metered dose inhalers

A method for forming a stabilized respiratory dispersion comprising the steps of:

• combining a plurality of perforated microstructures having a mean aerodynamic diameter of less than 5 μm and comprising at least one bioactive agent with a predetermined volume of suspension medium comprising at least one propellant to provide a respiratory blend wherein said suspension medium pernates said microstructures wherein more than 30% of the average particle volume of the perforated microstructures is permeated by said suspension medium;
• and
• mixing said respiratory blend to provide a substantidly homogeneous respiratory dispersion.

The method of claim wherein said propellant comprises a hydrofluoroalkane propellant.

A method for stabilizing a dispersion by reducing attractive van der Waals forces comprising

• providing a plurality of perforated microstructures having a mean aerodynamic diameter of less than 5 μm and;
• combining the microstructures with a suspension medium comprising at least one propellant wherein the wherein more than 30% of the average particle volume of the perforated microstrures is permeated by said suspension medium.

A respiratory dispersion for the pulmonary delivery of one or more bioactive agents comprising a suspension medium having dispersed therein a plurality of microparticles having a mean aerodynamic diameter of less than 5 μm and comprising greater than about 20% w/w surfactant and at least one bioactive agent wherein said suspension medium comprises at least one propellant.