Nebulizer choice for inhaled colistin treatment in cystic fibrosis

Study objectives: To develop practical ways of nebulizing colistin by deter mining the rate of drug output, total drug output, and particle-size distri bution of two commercially available jet nebulizers, the disposable Hudson 1730 Updraft II (Hudson Respiratory Care; Temecula, CA) and the reusable Pa ri LC Star breath-enhanced nebulizer (Pari Respiratory Equipment; Midlothia n, VA). Methods: The nebulizers contained colistin, 75 mg, in 4 mL of isotonic solu tion. Particle-size distribution was measured by helium-neon laser diffract ion, allowing calculation of the respirable fraction (RF), the mass of aero sol comprised of droplets < 5 <mu>m. Results: The mean (95% confidence interval [CI]) total rate of output of th e Updraft II was 2.6 mg/min (2.0, 3.1; n = 4) with 1.3 mg/min (1.0, 1.5) mg /min within the RF. The rate of output of the LC Star increased in a quadra tic relationship to the inspiratory flow, delivering 1.8 mg/min (0.7, 2.0; n = 4) with 1.4 mg/min (1.3, 1.6) within the RF, and 6.2 mg/min (5.6, 6.8) with 5.3 mg/min (4.8, 5.7) within the RF, at 0 L/min and 20 L/min inspirato ry flows, respectively. Efficiency, as the rate of expected pulmonary depos ition divided by rate of total output, was then calculated. The LC Star est imated 56% (51, 61) efficiency, with pulmonary delivery of 29% (26, 32) of the charge of the nebulizer, compared to the Updraft II at 22% (22, 23) eff iciency and expected pulmonary deposition of 10% (10, 10) of the dose. Conclusions: Colistin can be successfully nebulized with both nebulizers te sted. This study provides an estimate of in vivo efficiency and expected pu lmonary deposition that may be used in future trials.