Suitability of the upper airway models obtained from MRI studies in simulating drug lung deposition from inhalers.

ABSTRACT

PURPOSE: In this study, the suitability of the upper airway models, obtained by applying a magnetic resonance imaging method, in simulating in vivo aerosol deposition data is determined. METHODS: Depositions of salbutamol sulfate from two nebulizers in two models, one with constriction at the oropharynx (the constricted cast) and another model without that constriction (the wide cast), were determined. RESULTS: For the Sidestream and Ventstream nebulizer, 76 +/- 3% (mean +/- standard deviation) and 81 +/- 2% of the emitted dose deposited in the constricted cast, whereas 51 +/- 2% and 49 +/- 3% of the emitted dose deposited in the wide cast, respectively. These values were in good agreement with in vivo data. Mostly, increasing nebulizer charge volume (by normal saline) from 2.5 ml to 5 ml increased significantly the lung dose. However, the lung doses from the Sidestream and Ventstream nebulizer with 2.5 ml charge volume via the wide cast were (1.37 +/- 0.06 and 1.38 +/- 0.05 mg) significantly larger than those for the constricted cast with 5 ml charge volume (0.87 +/- 0.15 and 0.86 +/- 0.21 mg, respectively) (p = 0.005). CONCLUSIONS: The upper airway models closely simulated the in vivo deposition data. Optimizing the upper airway posture during inhalation via the nebulizers would be more efficient in increasing drug lung delivery than diluting their contents.