Effects of device design on patient compliance : Comparing the same drug in different devices.

Compliance with the prescribed inhaler dosage regimen and the manufacturer’s recommended inhalation technique are essential to achieve good control in asthma and COPD. A patient’s beliefs and education are important factors to ensure that they will use their inhalers as prescribed. Training patients how to use the correct inhalation technique is important. During this training session the patient’s ability to use the correct technique must be assessed. Dry powder inhalers (DPIs) have flow dependent dose emission properties and the inhalation flow achieved by a patient will be dependent on their inspiratory ability and the resistance of the inhaler. This has led to debates on ‘the optimal inhalation flow’ for each DPI. However the clinically important issue is to identify the inhalation flow below which the particles in the emitted dose would not be expected to be deposited into the lungs and so in the future this should be the focus of attention. DPIs are not generic devices and so should not be regarded as interchangeable. Once a patient is controlled, accepts and is familiar with one type of inhaler then a change of device is not recommended unless requested by the patient or they are unable to use the correct inhaler technique.