Enhancement of the extra-fine particle fraction of levofloxacin embedded in excipient matrix formulations for dry powder inhaler using response surface methodology.

Extra-fine particle fraction (eFPF, the fraction of particles with aerodynamic size <2 µm) is an essential metric to evaluate the deep lung delivery of dry powder inhalers (DPIs). The product of spray-drying has the potential to be applied in DPI formulations regarding its controllable size. This study performed an eFPF enhancement of levofloxacin DPI formulations by optimizing the spray-drying process parameters such as inlet temperature, feed flow rate, and gas flow rate, using a design space compiled from response surfaces.