Learning Objective

• Definition of a pharmaceutical aerosol

Pharmaceutical aerosols are pressurized dosage forms of medicaments in which solid or liquid drugs are dissolved or suspended in a propellant. Upon activating the valve, the contents are released in the form of mist, spray or stream of foam. These products are intended for topical or local application to the nose (nasal aerosols), oral cavity (lingual aerosols) or for lungs (inhalation aerosols). They can be fitted with valves enabling metered-dose delivery such as metered topical aerosols and metered-dose inhalers (MDI). In order to achieve effective delivery with inhalation aerosols, the particle size must be carefully controlled and the average particle size must be less than 5 µm. Aerosol sprays used for other purposes may contain particles up to several hundred micrometers in diameter.