Nebulisation of rehydrated freeze-dried beclomethasone dipropionate liposomes

Beclomethasone dipropionate (BDP) liposomes were prepared from various lipids, dilauroyl phosphatidylcholine (DLPC), dimyristoyl phosphatidylcholine (DMPC), dipalmitoyl phosphatidylcholine (DPPC), and hydrogenated soybean phosphatidylcholine (Epikuron 200 SH). A lipid with a low transition temperature (T(m)) (DLPC) incorporated a higher amount of BDP than lipid with a high T(m). The nebulisation of rehydrated freeze-dried BDP liposomes was carried out using a Pari LC Plus nebuliser and the generated aerosol characterised by an Andersen Cascade Impactor operated at 28.3 l/min. The rehydrated BDP-DLPC liposomes showed a higher output (78.3%) and a higher fine particle fraction (FPF) (75.0%) and smaller mass median aerodynamic diameter (MMAD) (3.31 microm) than the other rehydrated liposome preparations. Liposomes containing lipid with a high T(m) (DPPC and Epikuron) underwent aggregation during nebulisation. This was shown by the large increase in size of the DPPC liposomes from 15.78 to 47.51 microm and the Epikuron liposomes from 5.84 to 46.70 microm.