Novel cationic cellulose beads for oral delivery of poorly water-soluble drugs

Cellulose beads emerge as carriers for poorly water-soluble drugs due to their eco-friendly raw materials and favorable porous structure. However, drug dissolution may be limited by their poor swelling ability and the presence of closed pores caused by shrinkage of the pristine cellulose beads. In this study, novel cellulose beads that can swell in acidic environment were prepared by introducing ethylenediamine (EDA) on dialdehyde cellulose (DAC), thereby addressing the shrinkage and closed pore problem of cellulose beads. The effect of the ratio of EDA on the swelling behavior and amine content of beads was studied. Three model drugs with different physicochemical properties were selected to study the physical state of loaded drugs and their release behavior. According to the results of XRPD and DSC, indomethacin and itraconazole loaded in the beads were amorphous at a drug loading of 20%, but fenofibrate was partially crystalline. Both bead size and the ratio of amine groups influenced the release behavior of the model drugs. The in vitro dissolution results showed that the cationic beads greatly improved the solubility and dissolution rate of the drug compared with the crystalline drug. Beads with a small size and high ratio of EDA tend to achieve a better drug dissolution rate and cumulative release percentage. Physical stability studies of the itraconazole-loaded beads were also implemented under four different temperature/humidity conditions for up to two months. The results showed that crystallization only appeared after two months of storage at 40°/75% RH, and the drug maintained a non-crystalline state in the other three storage conditions (0 °C/0 %RH, 0 °C/32 %RH, 25 °C/32 %RH). In conclusion, the novel pH-responsive cationic cellulose beads show great potential as a carrier for improving the rate and extent of dissolution of poorly soluble drugs and maintaining supersaturation.