Dry powder inhalation as a potential delivery method for vaccines

Measles vaccine is administered to millions of children annually via a percutaneous injection. There are, however, compelling reasons to search for alternative routes of administration, especially in mass vaccination campaigns. Two key factors are (1) decreased stability of the vaccine upon reconstitution and, (2) the potential risks of contamination associated with needles. Dura has developed a unique inhaler that can deliver a powder dose via the pulmonary route for local or systemic action. The breath-actuated Spiros(R) inhaler uses electromechanical energy to aerosolize and deliver a consistent dose over a wide range of inspiratory flow rates. To achieve alveolar (deep lung) deposition for subsequent systemic absorption, dry-powder vaccine is size reduced to a mass median diameter between 1 and 5 mu m. Small vaccine particles are blended with an inert carrier to improve dispersion. Measles vaccine formulated as a powder blend may be more thermostable than existing reconstituted formulations. The Spiros(R) technology is available in three powder storage platforms. Two of these formats are designed specifically for moisture and/or light sensitive compounds and may be particularly suitable for delivery of measles vaccines in mass campaigns because their design (1) eliminates the need for powder reconstitution, and (2) reduces the risk of contamination. (C) 1999 Elsevier Science Ltd. All rights reserved.