Automatic actuation of a dry powder inhaler into a nonelectrostatic spacer

This article describes a new "automatic spacer" device, which has been developed to improve the delivery of inhaled medication to young children. In the device, a dry powder inhaler (DPI) is mechanically actuated into a nonelectrostatic spacer, producing an aerosol cloud of fine drug particles (aerodynamic diameter, < 4.7 microm) with a long half-life. The new device combines the principal advantages of the conventional spacer and the DPI. It has the potential to provide a high ratio between lung dose and pharyngeal dose, without need for coordination or forced inhalation, and it avoids exposure of the patient to the additives and propellants used in pressurized metered dose inhalers. Studies with the prototype device show a high yield of fine drug particles in the aerosol (mass median aerodynamic diameter, 2.8 microm), a high repeatability of drug delivery owing to the mechanical nature of the actuation (relative standard deviation, 12%), and a prolonged residence time of the fine particle aerosol (half-life of the fallout of the fine particles, 82 s). These features should prove advantageous in the treatment of young children with inhaled medication.