The lyophilisation and aerosolisation of liposomes for pulmonary drug administration

Lyophilisation of liposomes often results in aggregation and/or fusion of vesicles which are too large for dry powder inhalation to the lung. These issues are addressed in this paper which examines the influence of some excipients on liposome lyophilisation and the subsequent aerosolisation properties of the resultant dry powder formulations. A significant increase in aerosolised BDP liposomes size < 3.98 μm (fine particle fraction) was achievable by preparing liposomes with trehalose or lactose. These carbohydrates were equally effective in reducing the aggregation and fusion of lyophilised DMPC and DPPC liposomes. However, the performance of lactose was superior to that of trehalose with Epikuron liposomes. Micronising lyophilised Epikuron trehalose or lactose vesicles with a jet-mill also demonstrated an improvement in the fine particle fractions and aerodynamic diameters of the aerosolised liposomes.