An investigation of some of the factors influencing the jet nebulisation of liposomes.

Multilamellar egg phosphatidylcholine liposomes with or without cholesterol have been aerosolised using four jet nebulisers. The size of aerosols generated from liposome suspensions, as measured by laser diffraction, was independent of liposome size and bilayer composition. However, increasing the phospholipid concentration caused an increase in the median size of the secondary aerosol size, although the extent of this effect was dependent on the design on the nebuliser. The total mass output of liposomal aerosols was similar for the Pari-LC and Sidestream nebulisers, though the rate of output was higher for the Sidestream. In both cases, increasing lipid concentration produced a reduced rate of aerosol output. For all the nebulisers studied, a size selective process was found, resulting in the retention of the largest liposomes.