Preparation of NaCl Powder Suitable for Inhalation

The use of aerosolized hypertonic saline (4.5% NaCl) as an osmotic agent for bronchial provocation tests to identify people with asthma is problematic due to the inconvenience in administration using ultrasonic nebulizers. Delivery using dry powder inhalers is an attractive solution but production of inhalable powders of NaCl is challenging because of physical stability issues. In this study, dry powders of NaCl were prepared using an ultrasound-mediated precipitation process followed by spray drying. The resulting particles (mass median diameter, 2.12 ± 0.35 (mu)m) showed the typical cubic crystal habit of NaCl and were confirmed to be crystalline by X-ray powder diffraction. Dispersion of the particles by dry powder inhalers (Inhalator, Dinkihaler, and Aeroliser) showed aerosol performance (fine particle fraction, 18, 35, and 36%, respectively) suitable for the bronchoprovocation test. The present method can thus be a promising alternative for preparing dry powder NaCl aerosols for inhalation delivery.