Use of an impinging jet for dispersion of dry powder inhalation aerosols.

The dispersion of Ventodisk (salbutamol sulphate with lactose) from different drug reservoirs by an air jet at normal impingement is examined experimentally. The effect on dispersion efficiency of jet velocity, nozzle location, reservoir size and shape, and the loaded dose is investigated for possible design of new dosing methods or inhalers. Results show that higher jet velocity (as high as feasible), lower drug loading (2 mg or smaller), a cylindrical hole reservoir (6 mm in diameter and 3 mm in depth) and a medium distance (approximately 5 jet diameters) from the nozzle to the reservoir yield optimum dispersion. The dispersed fine particle dose improves by a factor of 2-3 times between optimized conditions and poor conditions.