Inhalable nanocomposite particles using amino acids with improved drug content and humidity resistance

In this study, we prepared various rifampicin-loaded poly(DL-lactide-co-glycolide) nanoparticles by changing the volume and pH of the aqueous phase to improve the content of rifampicin in the nanoparticles. The rifampicin content in the nanoparticles prepared in the aqueous phase volume of 40 mL (pH 4) was 1.36 times higher than that in the nanoparticles prepared in the aqueous phase volume of 100 mL (pH 7). From the results of in vitro release tests in phosphate-buffered saline at 37 °C for 24 h, we found that by reducing the volume and pH of the aqueous phase, the cumulative release rate of rifampicin from nanoparticles was significantly decreased. Then, we prepared nanocomposite particles using arginine and leucine as diluents. The aerodynamic diameters of the nanocomposite particles were measured using a cascade impactor. We found that the nanocomposite particles prepared using a diluent with arginine to leucine ratio of 1: 20 had the highest fine particle fraction value (32.63 ± 1.49%) and the particles were suitable for pulmonary delivery of bioactive materials deep in the lungs.