Tetrandrine Beads Using Alginate/polyvinyl Alcohol and Alginate‑carboxymethyl Cellulose: Not Ideal as Colon‑targeted Dosage Form

Abstract

Objectives: Colon drug delivery system should be able to maintain drug release until the system reaches its target. In this study, beads were
selected as drug carrier system to deliver tetrandrine to colon using a combination of two polymers, alginate and polyvinyl alcohol (PVA)
and also alginate and carboxymethyl cellulose (CMC). It was hypothesized that alginate/PVA beads and alginate‑CMC beads may be
able to protect the drug effectively while in the gastrointestinal tract and may deliver the drug at colon under the influence of colonic pH.
Materials and Methods: Beads were formulated into six formulae with different concentrations of polymer. Beads were characterized and
evaluated for in vitro drug release using dissolution method. Results: Beads’ Formula 3 (alginate and PVA 2:1) and Formula 6 (alginate and
CMC 2:1.5) were the best formulae with entrapment efficiency 32.12% and 39.83%, respectively. The drug release test was performed first
in hydrochloric acid (HCl) medium for 2 h, then in phosphate‑buffered pH 7.4 + 2% Tween 80 for 3 h, and finally in phosphate‑buffered
pH 6.8 + 2% Tween 80 medium for 3 h, successively. The results of drug release in HCl pH 1.2 were 84.13%, 73.12%, 66.57%, 85.59%,
78.26%, and 69.56%, for Formula 1, 2, 3, 4, 5, and 6, respectively. Conclusion: All type of beads showed the high release of tetrandrine in
HCl; hence, it is not ideal yet as a colon‑targeted dosage form.