Background: Drugs in the Biopharmaceutics Classification System (BCS) class II have low solubility and dissolution, as well as low bioavailability. Nanoparticles formulation is a strategy to overcome those problems by using chitosan, a polymer that can be used to prevent agglomeration or aggregation on nanoparticle preparations.

Purpose: This review will discuss the mechanism of enhancing the bioavailability and formulation methods of chitosan nanoparticles applying in BCS class II drugs.

Methods: The original articles used in this review were collected through google scholar, science direct, and pubmed with certain keywords for the period 2015−2020. There were 20 articles matched the inclusion criteria, then they were selected and organized in a narrative summary.

Results: In vitro study data on the percentage of drug released and in vivo pharmacokinetic parameters showed bioavailability enhancement. The mechanisms of enhancing the bioavailability of BCS class II drugs occur through size-reducing particles and enhancing the surface area of ​​the particles so that the solubility and dissolution of the drug increased. The formulation methods including high pressure homogenization, ionic gelation, precipitation, solvent evaporation, and spontaneous emulsification can produce nanoparticle sizes (10−1,000 nm).

Conclusion: Formulation of chitosan nanoparticles can be used to enhance the bioavailability of BCS class II drugs by increasing the surface area of the particles in contact with solvent media resulting in the increased dissolution.

Keywords: Chitosan nanoparticles, BCS class II, dissolution, pharmacokinetic, bioavailability.