Ionic cross-linking of sodium carboxymethyl guar gum as a mild method for microencapsulation of sensitive drugs, like proteins, is presented. When a solution of sodium salt of carboxymethyl guar gum, containing BSA as a model drug, is added, as droplets, to different multivalent metal ion solutions, they get cross-linked to form insoluble microbeads. The amount of protein retained, morphology of the resulting beads and the subsequent release of the retained protein is simulated intestinal fluids varied with the type of metal ion as well as it's concentration. Trivalent metal ions like Al+++ and Fe+++ were found to be superior to divalent metal ions like Ba+ +, Ca++, Cu++ and Cd++. The optimum concentration around which these ions provide maximum drug retention was found to be much lower for trivalent ions. Beads cross-linked with them released the protein over a longer duration in enzyme free simulated intestinal fluid, than those cross-linked with divalent ions. Mg++, Sr++, Co++ and Zn++ failed to form isolable beads.
ABSTRACT: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 ϩϩ and Ba ϩϩ is reported. Initially, guar gum is derivatized with carboxymethyl groups so that it forms durable, self-standing microbeads when its solution is dropped into CaCl 2 or BaCl 2 solutions. The swelling data of Ca ϩϩ and Ba ϩϩ crosslinked beads suggest that Ba ϩϩ crosslinks CMGG much more efficiently than Ca ϩϩ . The drug loading efficiency of these Ba ϩϩ /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 ϩϩ crosslinked carboxymethyl guar gum beads can be used for gastrointestinal drug delivery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.