Rapid pulmonary delivery of inhaled tobramycin for Pseudomonas infection in cystic fibrosis: A pilot project

Abstract

Background Patients with cystic fibrosis spend as much 30 min a day inhaling tobramycin. Could a new rapid system deposit the equivalent amount of tobramycin faster? Methods Six healthy adult males inhaled 5 ml (300 mg) of tobramycin from a breath enhanced nebulizer and either 125 mg (n = 3) or 150 mg (n = 3) from a vibrating membrane system with a large or small aerosol mixing chamber respectively. A radiolabel was added to the solution and shown to “track” with the tobramycin. Imaging was done with a dual headed gamma camera. Because the radiolabel will be cleared by mucociliary action during administration, algorithms were developed to allow the comparison of a slower system to a faster one. Results Both formulations were well tolerated. The lung deposition was 16.6 ± 3.2% (mean ± SD) of the charge dose delivered in 10.9 ± 1.0 min for the breath enhanced nebulizer versus 32.0 ± 5.1% delivered in 2.5 ± 0.4 min from the vibrating membrane system. The absolute pulmonary delivery of tobramycin was 49.9 ± 9.6 versus 43.9 ± 4.8 mg for the two systems respectively, differences that were statistically significant (pair t‐test) but unlikely to be clinically significant. There was a similar deposition of tobramycin for the 125 and 150 mg dose. Conclusions It is possible to deliver an equivalent amount of tobramycin in a shorter period of time with the new vibrating membrane system and a more concentrated formulation. These data will allow the design of a comparison in patients with CF. Pediatr Pulmonol. 2008; 43:753–759.