TY - JOUR T1 - Inspiratory flow resistance of marketed dry powder inhalers (DPI) JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - 4635 AU - Phillip Krüger AU - Benjamin Ehrlein AU - Michael Zier AU - Roland Greguletz Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/4635.abstract N2 - The device resistance of DPI is a significant factor to balance achievable flow rates with the efficient utilization of inspiratory air flow for powder dispersion and deagglomeration required for the therapeutic effect. This study assessed the device resistance and variability of currently marketed DPI for the treatment of COPD or asthma. The pressure drop and corresponding flow rate were measured at a defined pressure point or a constant flow rate (0– 100 L/min) using a test system with a mass flow meter, a differential pressure sensor connected to a sampling tube, a flow control valve, and vacuum pumps. Inspiratory flow resistance was calculated by linear regression using the method of least-squares. A broad range of device resistances was observed across the different inhaler types. The variability over different batches ranged from 0.8% (RSD Genuair®) to 9.1% (RSD Accuhaler™). Devices with low variability in their aerodynamic characteristic and a medium inspiratory resistance (e.g. Genuair®) can combine the positive aspects of achievable flow rates, consistent and efficient fine particle generation, and reduced impaction losses in the upper airways.View this table:Inspiratory flow rates through marketed inhalers (3 batches/product, 3 inhalers/batch = 9 inhalers/product) ER -