Respimat soft mist inhaler (SMI) in-vitro aerosol delivery with the ODAPT adapter and facemask

Abstract

INTRODUCTION The Respimat Soft Mist Inhaler (SMI) is a propellant-free inhaler that generates a fine aerosol mist suitable for inhalation. For patients requiring facemasks for medication delivery, the presence of the facemask influences the lung deposition. The purpose of this study was to assess, in vitro, the effect of the attachment of add-ons (ODAPT soft mist adapter with facemask) to the Respimat SMI on the medication delivery under different conditions and evaluate the efficacy of the ODAPT with facemask. METHODS The Spiriva Respimat SMI was tested twice (with and without add-ons) at 28.3 L/min and 60 L/min in 40%–50% and >90% relative humidity environments, using an 8-stage Andersen cascade impactor, enclosed in a sealed temperature-and-humidity-controlled chamber. The particle deposition was assessed by UV-visible spectrophotometry. RESULTS Increasing relative humidity shifts the particle size distribution toward larger particles due to the evaporation rate difference. At higher humidity levels, 18.7% and 20.3% of the medication delivered was lost in the add-ons at 28.3 L/min and 60 L/min, respectively. However, the fine particle fraction (FPF) was found to range between about 42% and 51% for 28.3 L/min and 41% and 50% for 60 L/min. No significant difference in FPF was found at different flow rates. CONCLUSION Minimal impact therapeutic drug delivery was achieved when using the ODAPT adapter with facemask for the Spiriva Respimat SMI with a loss of medication deposition of 7.39% and 16.23% under normal and high relative humidity, respectively, at 28.3 L/min and 18.84% and 9.64% under normal and high relative humidity, respectively, at 60 L/min.