Nebulisers convert liquids into a cloud of droplets suitable for respiration. Conventional nebulisers are widely used in both hospital and home. Their main advantage is that unlike other devices, they require little or no coordination on the part of the patient in order to use them.
The breathing pattern employed in the testing of nebulisers is particularly important since in vivo this determines the amount of active available to the user.
For this reason, the two tests specified in the Pharmacopoeias to characterise delivered dose, Active Substance Delivery Rate and Total Active Substance Delivered are based on tidal flow conditions generated by a breathing simulator, as opposed to fixed flow rates.