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Prediction of Intersubject Variability of Extrathoracic Deposition in Adults and Children

Finlay WH, Ruzycki CA, Moore CP, Martin AR.

RDD Europe 2019. Volume 1, 2019: 51-58.

Abstract:

A relatively straightforward method of predicting intersubject variability of extrathoracic deposition with inhaled aerosols is given. The method relies on previously developed in vitro algebraic deposition correlations that include the effects of variations in flow rate and airway size, but also includes intersubject variations in airway shape, and is applicable for aerosols with known or estimated particle size distributions. Ruzycki et al. found good agreement with in vivo data using this approach with nebulized aerosols. Here we extend the method to allow consideration of higher flow rates that occur with single breath inhalers, as well as deposition in children and infants. Since intersubject variability in extrathoracic deposition directly causes intersubject variability in lung dose, the method may be useful in estimating and accommodating intersubject variability during product development and clinical trial design.