Barium chloride crosslinked carboxymethyl guar gum beads for gastrointestinal drug delivery

A mild method for microencapsulation of sensitive drugs, such as proteins, employing a suitably derivatized carboxymethyl guar gum (CMGG) and multivalent metal ions like Ca++ and Ba++ is reported. Initially, guar gum is derivatized with carboxymethyl groups so that it forms durable, self‐standing microbeads when its solution is dropped into CaCl2 or BaCl2 solutions. The swelling data of Ca++ and Ba++ crosslinked beads suggest that Ba++ crosslinks CMGG much more efficiently than Ca++. The drug loading efficiency of these Ba++/CMGG beads, as a function of concentration of both metal ion as well as drug, was then determined using Bovine Serum Albumin as a model drug. The ability of these beads to protect the drug from the acidic environment of the stomach was investigated. It was found that a very little amount of the drug is released from the beads when they are suspended in NaCl–HCl buffer of pH 1.2 for 6 h. The beads were also shown to release almost the entire encapsulated drug when exposed to TRIS–HCl buffer of pH 7.4. Thus, the results indicate that Ba++ crosslinked carboxymethyl guar gum beads can be used for gastrointestinal drug delivery.