Preparation and characterization of lysozyme loaded liposomal dry powder inhalation using non-ionic surfactants

Delivering protein drugs through dry powder inhalation (DPI) remains a significant challenge. Liposomes offer a promising solution, providing protection for proteins from external environment and controlled release capabilities. Furthermore, the use of non-ionic surfactants plays a crucial role in protecting the activity of proteins because of how the surfactants positioning themselves at the liquid-gas interface during the spray-drying process. In this study, lysozyme-loaded liposomal DPI formulations were prepared using various non-ionic surfactants, including polysorbate 80, poloxamer 188, poloxamer 407, and sucrose stearate. Lysozyme solution and 1,2-distearoyl-sn-glycero-3-phosphatidylcholine liposomes were subjected through high-pressure homogenization to form lysozyme-loaded liposomes. Formulations of homogenized lysozyme liposomes were spray-dried and further characterized. The particle size of reconstituted liposomal lysozyme DPI was from 129.5 to 816.9 nm. The formulations showed encapsulation efficiency up to 32.5% with zeta potential value of around - 30 mV, and spherical structures were observed. The aerosol dispersion performance of the dry powder inhalers was evaluated with emitted doses reaching up to 103% and fine particle fractions up to 28.4%. Significantly higher lysozyme activity was confirmed in formulation with drug to PS 80 ratio of 1: 0.5 w/w (92.1%) compared to that of formulation containing no surfactant (59.8%). The formulation stood out as the only formulation that maintained protein activity while demonstrating good aerosol performance.