Development of a new inhaled swellable microsphere system for the dual delivery of naringenin-loaded solid lipid nanoparticles and doxofylline for the treatment of asthma.

This study developed a new dual delivery system of naringenin (NRG), a polyphenol, and doxofylline (DOX), a xanthine derivative, as an inhaled microsphere system. In this system, NRG has been first loaded into glyceryl tristearate-based solid lipid nanoparticles (NRG SLN), which were further loaded with DOX into swellable chitosan-tripolyphosphate-based microspheres (NRG SLN DOX sMS). The system was characterized based on particle size, PDI, zeta potential, surface morphology (SEM, AFM, and TEM), solid-state and chemical properties (XRD, IR, and NMR), aerodynamic parameters, drug loading, entrapment efficiency and in vitro drug release study. The optimized NRG SLN DOX sMS exhibited particle size, zeta potential, and PDI of 2.1 µm, 31.2 mV, and 0.310, respectively; a drug entrapment efficiency > 79 %; a drug loading efficiency > 13 %; cumulative drug releases of about 78 % for DOX and 72 % for NRG after 6 and 12 h, respectively; good swelling and desirable aerodynamic properties. In addition, in vivo studies conducted in mice, a murine model of asthma showed significant reductions in serum bicarbonate and eosinophil counts and improvement in respiratory flow rate, tidal volume, and bronchial wall lining compared with the asthmatic control group. Overall, this novel inhalable dual-delivery system may represent a good alternative for the effective treatment of asthma.