**5. Other inhalation devices**

### **5.1 Metered dose inhaler**

Pressurized metered-dose inhalers (pMDIs) are the most popular inhalers for the treatment of asthma and chronic obstructive pulmonary diseases. To date, only one study has attempted this type of device to aerosolize phage [64]. The phage cocktail suspension containing FKZ/D3 and KS4-M phages, was formulated in a reverse emulsion with Tyloxapol surfactant using hydrofluoroalkane 134a as the

propellant. A limited loss of phage activity (0.5–0.9 log) upon the actuation was observed, but the long term storage stability of the phages was not assessed. Further studies to examine the interactions between phage and liquefied propellant gas [65], and maximum loading capacity of phage/puff are required to move this inhaler choice forward.
