Objective: To formulate pH-sensitive spray dried microspheres loaded with an anti-cancer
drug, capecitabine, using hydrolyzed polyacrylamide-grafted-acacia gum (PAAm-g-AG) for colon targeted
Methods: The pH-sensitive PAAm-g-AG was synthesized by free radical polymerization and allowed
for alkaline hydrolysis.
Results: The obtained microspheres were sphere-shaped and drug encapsulation efficiency was found to
be from 76.29% to 97.66%. The dynamic swelling investigation suggested that the PAAm-g-AG attained
significant pH-sensitivity property. The in vitro drug release study witnessed that the microspheres
prepared with native AG alone were not capable of stopping the drug release within 5 h in
stomach and small intestinal pH. But, those microspheres prepared using pH-sensitive PAAm-g-AG
having crosslinked with glutaraldehyde (GA), have released small quantity of drug within 5 h, and highest
amount of drug was moved to colonic region in a controlled manner up to 24 h. Cross-linking with
GA reduced the premature drug release in the pH of stomach and small intestine and also assured most
of the drug released in colonic region. We observed an abrupt increase in drug release in the presence of
rat caecal contents due to the action of colonic bacteria on PAAm-g-AG polymer.