Synthesis and characterization of a novel pH-sensitive aluminum crosslinked carboxymethyl tragacanth beads for extended and enteric drug delivery

Carboxymethyl tragacanth (CM-TG) with a DS of 1.2 was synthesized and characterized for drug delivery using diclofenac sodium as a model drug. The mixture of CM-TG and drug was ionically crosslinked using aluminum chloride to form drug-loaded beads. The concentrations of 10 and 20% w/w solution of CM-TG were found to produce beads with acceptable qualities. The beads exhibited pH-dependent swelling. The highest swelling was observed at pH 6.8 which evidences the possibility to release the drug in the colon. FT-IR and TGA confirmed carboxymethylation of tragacanth and the absence of drug-polymer interaction. The diclofenac sodium entrapment efficiency was 30–35% while the loading varies from 4.5 to 18% w/w based upon the drug-polymer ratio. The beads could extend the drug release up to 180 min at pH 6.8. The pH-responsive CM-TG hydrogel beads are biocompatible and could be exploited as a new excipient in developing enteric release formulations.