NEBULIZER DELIVERY OF TOBRAMYCIN TO THE LOWER RESPIRATORY-TRACT

We characterized a tobramycin aerosol generated by five nebulizers: Mi cron One(R), Pulmosonic(R), Pulmo-Aide(R), DeVilbiss Model 65(R), and UltraNeb 100(R) by particle size and drug concentration. The Micron On e nebulizer did not produce a recoverable aerosol, while the Pulmosoni c had a minimal output; therefore three machines were examined for the ir ability to deliver tobramycin to the lower respiratory tract of pat ients with cystic fibrosis (CF). The DeVilbiss 65 had the greatest out put: with air as the carrier gas it produced an aerosol with >60% of t he particles having a mean mass aerodynamic diameter (MMAD) of >5.5 mu m. Using helox shifted the MMAD so that >65% of the particles were <5 .5 mu m. Increasing the power in the DeVilbiss 65 increased the output of particles >9.2 mu m, without a change in the particles <3.3 mu m, With air as the carrier gas the Pulmo-Aide and the UltraNeb 100 produc ed an aerosol with >60% particles, <3.3 mu m MMAD. Using helox the Ult raNeb 100 increased the amount of aerosol with a <3.3 mu m MMAD to 98% . Tobramycin delivery to the lower respiratory tract with the Pulmo-Ai de and UltraNeb 100 was compared using air or helox by measuring sputu m drug concentration. Pulmo-Aide failed to produce detectable tobramyc in in sputum in 2 out of 9 patients with CF. With the UltraNeb 100, al l patients had measurable sputum tobramycin immediately after administ ration (range, 16.2-3385 mu g/g), but no statistically significant dif ference was found when using either compressed air, helox, or ambient air. There was no correlation between pulmonary function and sputum to bramycin content. We conclude that the UltraNeb 100 consistently deliv ered tobramycin to the lower respiratory tract in patients with CF. (C ) 1994 Wiley-Liss, Inc.