Aerosolised drugs are prescribed for use in a range of inhaler devices and systems. Delivering drugs by inhalation
requires a formulation that can be successfully aerosolised and a delivery system that produces a useful aerosol of
the drug; the particles or droplets need to be of suffi cient size and mass to be carried to the distal lung or deposited
on proximal airways to give rise to a therapeutic eff ect. Patients and caregivers must use and maintain these aerosol
drug delivery devices correctly. In recent years, several technical innovations have led to aerosol drug delivery devices
with effi cient drug delivery and with novel features that take into account factors such as dose tracking, portability,
materials of manufacture, breath actuation, the interface with the patient, combination therapies, and systemic
delivery. These changes have improved performance in all four categories of devices: metered dose inhalers, spacers
and holding chambers, dry powder inhalers, and nebulisers. Additionally, several therapies usually given by injection
are now prescribed as aerosols for use in a range of drug delivery devices. In this Review, we discuss recent
developments in the design and clinical use of aerosol devices over the past 10–15 years with an emphasis on the
treatment of respiratory disorders.