PURPOSE: Jet nebulizers are typically classified as conventional (e.g. Salter 8900®), active venturi (e.g. Sidestream®), or breath-enhanced (e.g. Pari LC Plus®) depending on air flow characteristics through the device. The in vitro aerosol characteristics of drugs like albuterol, ipratropium bromide and budesonide are likely to be affected by differences in nebulizer design.
METHODS: The nebulizers –three units per brand - were randomly selected and run with an Inspiration Elite compressor. Study drugs were: albuterol 2.5 mg, 3 mL, ipratropium bromide 0.5 mg, 2.5 mL, and budesonide 0.5 mg, 2 mL. Respirable fractions, particle sizes (mass median aerodynamic diameter, MMAD), and output rates (μg/min) were determined with an In-Tox cascade impactor as per FDA guidelines (Piper Medical Products, Carmichael, CA). Tests were run in triplicate, drugs were analyzed with a spectrophotometer technique, and the statistical analyses performed with ANOVA.
RESULTS: The mean respirable fractions for the three drugs ranged between 72.0-77.0% with Sidestream, between 65.7-72.0% with Pari and between 60.3-68.0% with Salter nebulizers. The differences were statistically significant for albuterol p=0.0076, and ipratropium p=0.0405. The MMADs ranged between 2.5-2.6 μm with Sidestream, 2.6-3.1 μm with Pari, and 2.7-3.1 μm with Salter (ns). The output rates for albuterol were 170.4 μg/min (Sidestream), 159.9 μg/min (Pari), and 90.8 (Salter). For ipratropium the output rates were 44.7 μg/min (Sidestream), 53.7 μg/min (Pari), and 27.9 (Salter). The output rates for budesonide were 46.6 μg/min (Sidestream), 52.8 μg/min (Pari), and 20.5 μg/min (Salter). The differences were statistically significant for all drugs: albuterol p=0.0083, ipratropium p=0.0457, and budesonide p=0.0011.
CONCLUSION: The results indicate that sophistication in nebulizer design, as embodied by the Sidestream (active venturi), and Pari LC Plus (breath-enhanced) nebulizers, provides the benefit of improved aerosol characteristics in comparison with the conventional nebulizer design.
CLINICAL IMPLICATIONS: The in vitro aerosol characteristics might be of importance when selecting jet nebulizers in the clinic.
DISCLOSURE: Kurt Nikander, Employee I am an employee of Respironics Respiratory Drug Delivery which paid for the in vitro study and which manufactures one of the nebulizers included in the in vitro study.