AN IN-VITRO TECHNIQUE FOR CALCULATING THE REGIONAL DOSAGES OF DRUGS DELIVERED BY AN ULTRASONIC NEBULIZER

This study describes an in vitro technique for calculating the dosages of drug delivered to the different regions of the human lung by an ul trasonic nebulizer. The technique uses phase Doppler anemometry to mea sure particle sizes. Tidal breathing is simulated with a reciprocating pump. Inhalation is divided into an interval in which the sizes of th e particles are nearly independent of the relative humidity (RH) of th e inlet ambient air and a second interval in which the particles have evaporated. The numerical hygroscopic lung deposition model of Staplet on, Finlay, and Zuberbuhler (J. Aerosol Med. 7, 325, 1994) is used to calculate the regional dosages. The methodology is applied to the DeVi lbiss Aerosonic(R) ultrasonic nebulizer for 2.5 ml nebules of 1 mg ml( -1) Ventolin(R). The dosage of drug delivered to the extrathoracic, br onchial, and pulmonary regions is 0.42, 0.10, and 0.22 mg, respectivel y, at an inlet RH of 95% and 20 degrees C. The corresponding values fo r RH = 3% are 0.39, 0.097, and 0.22 mg.