The conventional ultrasonic nebulizer proved inefficient in nebulizing a suspension

A study was undertaken to compare the amount of nebulized budesonide suspen sion and nebulized terbutaline sulphate solution inhaled by healthy adult s ubjects when conventional jet and ultrasonic nebulizers were used. Ten heal thy subjects (5 male; age range, 16-52 years) used two conventional nebuliz ers: the Spira Elektro 4 jet nebulizer (Respiratory Care Center, Hameenlinn a, Finland) and the Spira Ultra ultrasonic nebulizer (Respiratory Care Cent er) in a breath-synchronized mode with each drug. The amount of drug inhale d, the inhaled mass, was defined as the amount of drug deposited on a filte r between the inspiratory port of the nebulizer and the mouthpiece. The amo unt of budesonide and terbutaline sulphate was determined by reversed-phase high-performance liquid chromatography. Single-dose respules were used (0. 5 mg of budesonide and 5.0 mg of terbutaline sulphate), and nebulization ti me up to the defined gravimetric output was recorded. The inhaled mass of b udesonide varied depending on the nebulizer used, whereas the inhaled mass of terbutaline was unaffected by the choice of nebulizer. The median inhale d mass of budesonide was 31.4% of the nominal dose (i.e., dose of drug in t he respule per label claim) with the Spira Elektro 4 and 9.9% with the Spir a Ultra, whereas the median inhaled mass of terbutaline was 50% with the Sp ira Elektro 4 and 52% with the Spira Ultra. It appears that a suspension is generally more difficult to nebulize than a solution and that the budesoni de suspension should not be used in conventional ultrasonic nebulizers.