[Development of a spacer for inhaled corticosteroid. Evaluation using flunisolide metered dose aerosol]

As optimal therapy with inhaled steroids invariably demands the use of a spacer (Nolte, 1989), a specific inhalation device adapted to flunisolide metered dose inhaler was required. For this purpose, various inhalation chambers varying in geometry and material were investigated. The decisive criterion was the percentage of inhalable particles (diameter less than 8 microns) dispensed by the device. Separation of larger particles was possible in spacers with a relatively small volume. The highest dispensing rate being achieved with conical or pear-shaped inhalation chambers. An increase in spacer volume beyond 320 ml failed to improve the percentage of inhalable active substance. The results demonstrate that the spacer, dimensioned to the smallest possible volume, specially developed for Inhacort MDI has optimal dispensing characteristics for flunisolide.