Abstract
INTRODUCTION: Use of submicrometer particles combined with condensational growth techniques has been proposed to reduce drug losses within components of high-flow nasal cannula therapy systems and to enhance the dose reaching the lower respiratory tract. These methods have been evaluated using continuous inhalation flow rather than realistic inhalation/exhalation breathing cycles. The goal of this study was to evaluate in vitro aerosol drug delivery using condensational growth techniques during high-flow nasal cannula therapy using realistic breathing profiles and incorporating intermittent aerosol delivery techniques.
METHODS: A mixer-heater combined with a vibrating mesh nebulizer was used to generate a submicrometer aerosol using a formulation of 0.2% albuterol sulfate and 0.2% sodium chloride in water. Delivery efficiency of the aerosol for 1 min through a nasal cannula was considered using an intermittent delivery regime with aerosol being emitted for either the entire inhalation time (2 s) or half of the inhalation period (1 s) and compared with continuous delivery. The deposition of the aerosol was evaluated in the nasal delivery components (ventilator tubing and cannula) and an in vitro adult nose-mouth-throat (NMT) model using 3 realistic breathing profiles.
RESULTS: Significant improvements in dose delivered to the exit of the NMT model (ex-NMT) were observed for both condensational growth methods using intermittent aerosol delivery compared with continuous delivery, and increasing the tidal volume was found useful. The combination of the largest tidal volume with the shortest intermittent delivery time resulted in the lowest respiration losses and the highest ex-NMT delivered dose.
CONCLUSIONS: Intermittent aerosol delivery using realistic breathing profiles of submicrometer condensational growth aerosols was found to be efficient in delivering nasally administered drugs in an in vitro airway model.
- high-flow nasal cannula therapy
- condensational growth
- submicrometer aerosol
- in vitro airway model
- pulmonary drug delivery
- nasal cannula
Footnotes
- Correspondence: Michael Hindle PhD, Department of Pharmaceutics, Room 442, Virginia Commonwealth University, 410 N 12th Street, Richmond, VA 23298-0533. E-mail: mhindle{at}vcu.edu.
The authors are employees of Virginia Commonwealth University. Virginia Commonwealth University is seeking patent applications with respect to the technology described, which if licensed may result in a financial interest to the authors.
This study was funded by National Institutes of Health grant R01 HL10733.
Dr Hindle presented a version of this paper at the 19th International Society of Aerosols in Medicine (ISAM 2013) Congress, held April 6–10, 2013, in Chapel Hill, North Carolina.
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