Effect Formulation Variables on Physicochemical Characteristics and Drug Release Potential of Oral Glipizide Microspheres

Abstract

In the present research work, guar gum (GG) microspheres containing glipizide were prepared by emulsification cross-linking method using polyvinyl alcohol (PVA) coating polymer and glutaraldehyde as a cross-linking agent. The physical state of the drug in the formulation was determined by Fourier transformation infra-red spectroscopy (FTIR) and differential scanning calorometry (DSC). The influences of process variables like concentration of polymer (s), copolymer, cross linking agent, surfactant, and plasticizer were evaluate on drug content, encapsulation efficiency, surface morphology, mean particle size, swelling ratio, mucoadhesive property and in vitro release studies. The shape and surface characteristics were determined by scanning electron microscopy (SEM). Particle size distribution was determined by standard sieve analysis. Particle size, shape and surface morphology, swelling ratio, drug entrapment efficiency and in-vitro release were significantly affected by concentration of guar gum, plasticizer and glutaraldehyde. FTIR and DSC studies revealed the absence of drug polymer interactions. The drug entrapment efficiency was obtained in the range of 81.30-94.24 %w/v. In-vitro drug release profile glipizide from microbeads was examined in simulated intestinal pH 7.4 at end of 12h. The mechanism of drug release from GG microspheres was diffusion controlled followed by First order kinetics and whereas GG-PVA coated microspheres approaching to near Zero- order kinetics.