Novel inhalable nano-based/microparticles for enhanced sustained pulmonary delivery of remdesivir - A patient malleable treatment for coronaviruses infection: In vitro aerosolization, cytotoxicity assays and antiviral activity studies

Remdesivir (RDV) is an antiviral used in potential treatment of SARS-COV-2 infection during the COVID-19 pandemic worldwide. However, it is still limited to IV administration for hospitalized patients. Therefore, we report herein successful development of RDV-loaded nanosuspensions (NS) using polycaprolactone and pluronic® F127, for the first time. The optimized RDV-NS was further loaded into inhalable nano-based/microparticles (OLN-microparticles) via co-spray drying with hyaluronic acid and mannitol. OLN-microparticles exhibited high yield value ∼80.56 %, with satisfactory entrapment efficiency and drug loading percent ∼97.27 ± 1.84 % and 3.92 ± 0.07 %, respectively. Carr's index was equal to 22.7 ± 11.67 % indicating good flowability properties. Scanning electron microscopic analysis showed spherical-shaped particles. Transmission electron microscope demonstrated grape-shaped clumps surface porosity. OLN-microparticles exhibited excellent aerodynamic features including; emitted fraction ∼97.46 ± 1.70 %, respirable particle fraction 53.77 ± 0.2 %, effective inhalation index 72.39 ± 1.40 %, and mass median aerodynamic diameter 2.25 ± 0.01 μm. Compared to plain RDV, OLN-microparticles showed significantly enhanced sustained release (p