Fabrication of an aprepitant nanosuspension using hydroxypropyl chitosan to increase the bioavailability

Aprepitant has been classified into BCS class IV, which has low permeability and poor water solubility, resulting in low bioavailability. This study focused on improving its permeability and solubility in order to improve the oral bioavailability of aprepitant. Hydroxypropyl chitosan (HPCS) was used as a stabilizer for the nanosuspension and wet milling was utilized for improving aprepitant's bioavailability and solubility. The resulting nanosuspension size was 151 ± 14.5 nm and its zeta potential was 63.5 ± 0.34 Mv. The spectral characteristics (XRPD, DSC, TEM) of the nanosuspension suggested that aprepitant existed in the crystalline form and that nanosuspension had 2-fold higher solubility than aprepitant. Hydroxypropyl chitosan can significantly reduce the TEER of Caco-2 cells and the Papp of the suspension in Caco-2 cells increased by 2.2 times compared with aprepitant. The relative bioavailability of the nanosuspension was 147.7% compared with the commercial capsule.