Demystifying Dry Powder Inhaler Resistance with Relevance to Optimal Patient Care.

The selection of an inhaler device is a key component of respiratory disease management. However, there is a lack of clarity surrounding inhaler resistance and how it impacts inhaler selection. The most common inhaler types are dry powder inhalers (DPIs) that have internal resistance and pressurised metered dose inhalers (pMDIs) that use propellants to deliver the drug dose to the airways. Inhaler resistance varies across the DPIs available on the market, depending largely on the design geometry of the device but also partially on formulation parameters. Factors influencing inhaler choice include measures such as flow rate or pressure drop as well as inhaler technique and patient preference, both of which can lead to improved adherence and outcomes. For optimal disease outcomes, device selection should be individualised, inhaler technique optimised and patient preference considered. By addressing the common clinically relevant questions, this paper aims to demystify how DPI resistance should guide the selection of the right device for the right patient.