High inhaler resistance does not limit successful inspiratory maneuver among patients with asthma or COPD

Introduction: There has been an active discussion on the sustainability of inhaler therapy in respiratory diseases, and it has cast a shadow on pMDIs which rely on propellant with high global warming potential (GWP). DPIs offer a lower GWP and effective alternative, but there has been concern whether all patients can generate sufficient inspiratory effort to disperse the drug. This review focuses on airflow resistance of DPIs and its clinical relevance.Areas covered: For this narrative review, we searched the literature for studies comparing flow patterns with different devices. We also included a section on clinical trials comparing reliever administration with DPI, pMDI with spacer, and nebulizer during exacerbation.Expert opinion: The evidence supports the efficacy of DPIs irrespective of respiratory condition or age of the patient even during acute exacerbations. Air flow resistance does not limit the use of DPIs and the patients were able to generate sufficient inspiratory flow rate with almost any device studied. None of 16 identified clinical trials comparing reliever administration via DPIs to other types of devices during exacerbation or bronchial challenge showed statistically significant difference between the device types in FEV1 recovery. DPIs performed as well as other types of inhaler devices even during asthma or COPD exacerbation.