Preparation and Optimization of Amorphous Ursodeoxycholic Acid Nano-suspensions by Nanoprecipitation based on Acid-base Neutralization for Enhanced Dissolution

Background: Ursodeoxycholic acid, usually used to dissolve cholesterol gallstones in clinic, is a typical hydrophobic drug with poor oral bioavailability due to dissolution rate-limited performance. The objective of this study was to increase the dissolution of ursodeoxycholic acid by amorphous nanosuspensions.

Methods: Nanoprecipitation based on acid-base neutralization was used to prepare the nanosuspensions with central composite design to optimize the formula. The nanosuspensions were characterized by particle size, morphology, crystallology and dissolution.

Results: The ursodeoxycholic acid nanosuspensions showed mean particle size around 380 nm with polydispersion index value about 0.25. Scanning electron microscope observed high coverage of HPMC-E50 onto the surface of the nanosuspensions. Differential scanning calorimetry and powder X-ray diffractometry revealed amorphous structure of the ursodeoxycholic acid nanosuspensions. A significant increase of dissolution in acidic media was achieved by the amorphous nanosuspensions compared with the physical mixture.

Conclusion: It can be predicted that the amorphous nanosuspensions show great potential in improving the oral bioavailability of ursodeoxycholic acid.