Aerosol characterisation of nebulised liposomes co-loaded with erlotinib and genistein using an abbreviated cascade impactor method

Erlotinib and genistein co-loaded liposomes were prepared by the thin-film hydration method. The effect of probe sonication as a size reduction method on drug incorporation and the properties of aerosols generated using air-jet and vibrating-mesh nebulisers was studied. The use of the Next Generation Impactor (NGI) to characterise inhaler formulations is limited by the need accurately to quantify drug deposited across 8 stages and is labour intensive to use. The Fast Screening Impactor (FSI) comprising two impaction stages was compared with the NGI to evaluate its applicability as a simple screening and labour-saving tool to characterise nebulised systems. For the developed liposomal formulations, an air-jet nebuliser generated a two-fold higher fine particle fraction (FPF) than a vibrating-mesh nebuliser. The findings demonstrated that the cooled FSI (5°C) operated at 15 L/min was effective in differentiating the aerosol properties of the nebulised liposome formulations investigated. Overall, the optimised co-loaded liposomes were more effectively delivered by an air-jet nebuliser, than from a vibrating-mesh nebuliser over a 10 min period as determined using the abbreviated impactor.