What plays a role in the choice of inhaler device for asthma therapy?

Inhalation is the preferred route of delivery for anti-asthma drugs. However, in reality inhalers are often prescribed on an empirical basis rather than on evidence-based awareness. Asthma management guidelines also guide inhaler choice, but they offer non-specific advice regarding inhaler choice, are very long and complicated and not conducive to rapid assimilation by a busy GP. In addition, device selection criteria differ according to who you are asking (i.e. the inhalation technologist, the physician or the patient). The ideal inhaler should be small and have a guided sequence of inhalation, leading patients in a logical sequence of events through the inhalation manoeuvre. It should be breath-activated, releasing medication only when all prerequisites for successful inhalation are met. Most importantly, there should be flow-independent deposition of drug in the lungs and feedback on the successfully performed inhalation manoeuvre to reassure the patient that the drug has been successfully released from the inhaler. The ideal inhaler should also have a low intrinsic airflow resistance, making it suitable for use by patients who have a low inspiratory airflow (e.g. children and elderly patients). In order to check for compliance, the ideal inhaler should have an accurate dose counter which is linked to correct inhalation rather than simply to dose release, and patients should be able to use an identical inhaler device to deliver each of their different medications. Finally, from an environmental and cost-effectiveness point of view, the ideal inhaler should be refillable. Among the currently available dry powder inhalers the Novolizer device fulfils several characteristics of an ideal inhaler for the treatment of asthma and chronic obstructive pulmonary disease (COPD).