Is inhalation rate important for a dry powder inhaler? Using the In-Check Dial to identify these rates

Abstract

The fraction of the emitted dose from an inhaler that has the potential to be deposited into the lungs is known as the fine particle dose (also the respirable dose). During inhalation all dry powder inhalers require a 'force' to be created inside the device so that a fine particle dose is generated from the formulation in the metering chamber. This 'force' is formed by the inhalation rate used together with the resistance (and hence design) inside an inhaler. Studies have shown that the fine particle dose is related to the clinical effect whilst other studies have reported that this dose can be dependent on the inhalation rate used. The inhalation technique recommended by the manufacturer of an inhaled device should, therefore, be used. For those dry powder inhalers that demonstrate significant flow dependent dosage emission it is important that patients use the most desirable rate that has been reported. The In-Check Dial is a simple and ease to use meter that can be used to measure the inhalation rate of a patient when they use each of the commonly prescribed inhalers that are currently available. This meter can be used to identify the most suitable inhaler for each individual. © 2002 Published by Elsevier Science Ltd.