The present and future of inhalation therapy for the management of obstructive airway diseases: Emphasis on pressurized metered-dose inhalers

Inhalation therapy has an ancient history and has been recognized as the most effective and safe way of delivering pharmaceutical compounds directly to the airways for the treatment of respiratory diseases. Nowadays, a great variety of devices exist;nebulizers, soft mist inhalers (SMIs), pressurized Metered Dose Inhalers (pMDIs) and single- or multi-dose Dry Powder Inhalers (DPIs). The choice for the optimal device is patient-specific and depends on the advantages and disadvantages of each device category, and the patients' age and capacity to use them correctly. Factors that determine therapeutic success, apart from the previously mentioned, are: the physician-patient relationship, the patient's opinion, willingness, and preferences for certain medical devices, and proper training on device use. Various sources of evidence indicate that frequent change of devices is associated with treatment failure and should be avoided in order to achieve good therapeutic outcomes. The most frequently used types of inhalation devices for management of chronic and acute obstructive respiratory diseases are the pMDIs. Despite having some environmental footprint and requiring a good technique by the users to achieve reliable therapeutic effects, these devices are essential tools for primary care physicians and pulmonologists. In the COVID-19 era, and despite diametrically opposed opinions on the appropriateness of using nebulizers, most experts recommend against their use in order to reduce the potential risk of spreading the SARS-CoV-2 virus. If required, most experts recommend the use of pMDI via a spacer, except for life threatening exacerbations. The ongoing research, to improve the underlying technologies of these devices, introduce environmentally friendlier propellants and combine these devices with modern applications of telemedicine and artificial intelligence, creates new pathways for the continuous utilization of these inhalation devices in everyday clinical practice.