Nano‐in‐Microparticles for Aerosol Delivery of Antibiotic‐Loaded, Fucose‐Derivatized, and Macrophage‐Targeted Liposomes to Combat Mycobacterial Infections: In Vitro Deposition, Pulmonary Barrier Interactions, and Targeted Delivery

Nontuberculous mycobacterial infections rapidly emerge and demand potent medications to cope with resistance. In this context, targeted loco‐regional delivery of aerosol medicines to the lungs is an advantage. However, sufficient antibiotic delivery requires engineered aerosols for optimized deposition. Here, the effect of bedaquiline‐encapsulating fucosylated versus nonfucosylated liposomes on cellular uptake and delivery is investigated. Notably, this comparison includes critical parameters for pulmonary delivery, i.e., aerosol deposition and the noncellular barriers of pulmonary surfactant (PS) and mucus. Targeting increases liposomal uptake into THP‐1 cells as well as peripheral blood monocyte‐ and lung‐tissue derived macrophages. Aerosol deposition in the presence of PS, however, masks the effect of active targeting. PS alters antibiotic release that depends on the drug's hydrophobicity, while mucus reduces the mobility of nontargeted more than fucosylated liposomes. Dry‐powder microparticles of spray‐dried bedaquiline‐loaded liposomes display a high fine particle fraction of >70%, as well as preserved liposomal integrity and targeting function. The antibiotic effect is maintained when deposited as powder aerosol on cultured Mycobacterium abscessus. When treating M. abscessus infected THP‐1 cells, the fucosylated variant enabled enhanced bacterial killing, thus opening up a clear perspective for the improved treatment of nontuberculous mycobacterial infections. Nano‐in‐microparticles for aerosol delivery of antibiotic‐loaded and fucose‐derivatized liposomes are developed to combat mycobacterial infections. In vitro studies with various phagocytic cell types reveal the benefits of macrophage‐targeted pulmonary delivery, which oftentimes is complicated by the interaction of antibiotics with pulmonary barriers, if delivered in nonencapsulated form. The inclusion of pulmonary mucus and surfactant into such models helps to estimate key factors that may influence therapeutic outcomes.