Azithromycin-loaded respirable microparticles for targeted pulmonary delivery for the treatment of pneumonia

Pneumonia is a major contributor to infection-based hospitalizations and deaths in the United States. Antibiotics such as azithromycin (AZM), although effective at managing pneumonia, often suffer from off-target diffusion and poor bioavailability when administered orally or via intravenous injection. The formation of biofilms at the disease sites makes the treatment more complicated by protecting bacteria from antimicrobial agents and thus necessitating a much higher dosage of antibiotics to eradicate the biofilms. As such, targeted pulmonary delivery of antibiotics has emerged as a promising alternative by providing direct access to the lung while also allowing higher local therapeutic concentrations but minimal systemic exposure. In this study, AZM was encapsulated in N-fumaroylated diketopiperazine (FDKP) microparticles for efficient pulmonary delivery. Both in vitro and in vivo results demonstrated that AZM@FDKP-MPs administered via intratracheal insufflation achieved at least a 3.4 times higher local concentration and prolonged retention times compared to intravenous injection and oral administration, suggesting their potential to better manage bacterial pneumonia.