Unsuccessful delivery of tetrandrine from colon-targeted dosage forms comprising alginate/hydroxypropyl methylcellulose and alginate–chitosan beads

Objective: The objective of this study was to optimize the formulations of antifibrotic tetrandrine beads using alginate and various concentrations of hydroxypropyl methylcellulose (HPMC) and chitosan. Methods: Beads were formulated with six (F1–F6) concentrations of polymer and were then characterized using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction; these beads were used for measurements of moisture contents, swelling, and in vitro drug release. Results: Beads with the highest concentrations of HPMC and chitosan produced the highest entrapment efficiencies of 49.83% and 50.71%, respectively. Moreover, drug release under stomach conditions (HCl pH 1.2 medium) was restricted to 75.01%, 61.01%, 51.86%, 74.84%, 66.00%, and 41.63% with increasing HPMC and chitosan concentrations (F1–F6, respectively). Conclusion: Beads of all formulations showed inadequate retention of tetrandrine under pH conditions of the upper gastrointestinal tract and would likely be unsuccessful as colon-targeted dosage forms.