Tailoring of locust bean gum and development of hydrogel beads for controlled oral delivery of glipizide

Abstract

In this study, carboxymethyl derivative of locust bean gum was prepared, characterized, and its gelling ability with different concentrations (1-5% w/v) of aluminum chloride (AlCl(3)) was utilized for the development of glipizide-loaded beads in a completely aqueous environment. The beads were spherical when observed under a scanning electron microscope. Increase in gelling ion concentration decreased the drug entrapment efficiency from 97.68% to 95.14%. The beads swelled more slowly in pH 1.2 KCl-HCl buffer and exhibited a slower drug release pattern than that observed in pH 7.4 phosphate buffer. Irrespective of the dissolution media, the drug release became slower at higher AlCl(3) concentration. The drug release in alkaline medium was found to be controlled by a combination of diffusion as well as polymer relaxation phenomena. Comparing the release profiles, it was observed that the beads treated with 5% AlCl(3) provided slower drug release up to 10 h in alkaline medium without any sign of disintegration and, thus, this formulation was selected for further studies. Fourier transform infrared (FTIR) spectroscopy indicated the stable nature of the drug in the beads. Differential scanning calorimetry and X-ray diffraction analysis showed that most of the drug remained in amorphous state in the beads. Stability study indicated no statistical significant difference in drug entrapment efficiency of the beads. In vivo activity of the beads was tested and a prolonged hypoglycemic effect was achieved. Hence, carboxymethyl locust bean beads could be a potential carrier for controlled oral delivery of glipizide.