There are three major types of handheld device to deliver drugs to the lungs, namely pressurized metered dose inhaler (“pMDI”), dry powder inhaler (“DPI”) and soft mist inhaler (“SMI”).

a) Briefly explain how aerosol is generated by each device. (3 marks)

b) Describe the key techniques in inhalation manoeuvres in order to allow proper drug deposition in the lung for each device (6 marks)

c) How does the use of spacer device improve delivery efficiency of pMDI? (3 marks)

d) Explain how particle size distribution can affect drug deposition in the lungs (3 marks)