ABSTRACT
Liquefied compressed gases are preferred over non-liquefied compressed gases such as nitrogen or carbon dioxide because they offer the following critical advantages for inhalation therapy: The discharge of defined aliquots of propellant from the metered dose inhaler (MDI) will undergo flash evaporation to give an aerosol of very small particles. The various MDI formulation options are described in detail later together with a description of some of the alternative options for input drug substance. More recently, low-surface-energy coatings based upon perfluoropolymers have been proposed for use with hydrofluoroalkane propellant systems. Glass bottles are not widely used because of their greater weight and potential fragility. The main plastic body of actuator surrounds and protects the aerosol canister, and veins within the actuator help to locate the canister so that when it is depressed by the patient to release the dose, the canister moves straight down without flexing valve stem. The disassembled valve components are examined for dimensional accuracy and surface quality.
