AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Evaluating the Effect of Altitude on Medium-High Resistance Dry Powder Inhalers
Conor A. Ruzycki, Andrew R. Martin, Reinhard Vehring, WARREN H. FINLAY, University of Alberta
Abstract Number: 276 Working Group: Health Related Aerosols
Abstract An experimental setup capable of simulating high altitude conditions was used to evaluate the performance of three medium-to-high resistance, commercially available dry powder inhalers, including Symbicort$^R Turbuhaler$^R, Pulmicort$^R Turbuhaler$^R, and Asmanex$^R Twisthaler$^R, at a simulated high elevation of 4300 m, with controls established at an elevation of 700 m (the elevation of Edmonton, Alberta, Canada). Inhaler performance was quantified based on measurements in a Next Generation Impactor placed downstream of an Alberta Idealized Throat using a similar procedure to that specified in the USP 601 monograph.
Using standard pressure drops, all inhalers showed consistent performance when maintaining a 4 kPa pressure drop across the device regardless of altitude. When instead using constant volumetric flowrates at altitude, resulting in lower pressure drops being generated across the devices, Pulmicort Turbuhaler and Asmanex Twisthaler showed decreases in performance; at a volumetric flowrate of 55 L/min, deposition in plates 2-8 of the NGI with the Pulmicort Turbuhaler decreased from 41% of label claim at an elevation of 700 m to 27% at an elevation of 4300 m. For Asmanex Twisthaler used at a volumetric flowrate of 50 L/min, deposition in plates 2 to 8 of the NGI decreased from 13% of label claim at an elevation of 700 m to 9% at an elevation of 4300 m.
When devices were evaluated at lower inhalation flow rates (considered on the threshold of reduced performance in vivo), all inhalers yielded relatively consistent, though poor, performance using either constant pressure drops or matched flow rates regardless of altitude.
These results indicate that when medium-to-high resistance DPIs are used with a standard pressure drop of 4 kPa, device performance appears to be independent of altitude. However, when certain DPIs are instead evaluated using constant volumetric flowrates, altitude may cause small but significant decreases in device performance.