Chitosan-clay matrix tablets for sustained-release drug delivery: Effect of chitosan molecular weight and lubricant

Matrix tablets prepared using chitosan-clay microparticles with various molecular weights (MWs) of chitosan were characterized in terms of hardness, swelling, and drug release. Moreover, the effect of magnesium stearate on the physical properties and drug release of the tablets was also examined. Montmorillonite clay, magnesium aluminum silicate (MAS), was used in this study. The results showed that chitosan-MAS microparticles with different chitosan MWs prepared by spray drying had similar micromeritic properties but displayed different nanocomposite types. The microparticles possibly possessed plastic deformation under the compression pressures to form matrix tablets. The tablets had greater hardness with increasing chitosan MW. Increasing the chitosan MW caused greater swelling of the tablets in acidic medium but reduced swelling in neutral medium. Chitosan-MAS tablets presented sustained-release patterns in both acidic and neutral media, and the drug release of the tablets in neutral medium decreased when using chitosan of higher MW. Furthermore, the introduction of up to 5%w/w magnesium stearate provided the tablets with lower hardness, higher friability, and lower drug release in acidic medium. These findings suggest that chitosan MW and lubricant content are important factors in the formulation of chitosan-MAS tablets and these tablets present good potential for oral sustained release drug delivery. (C) 2016 Elsevier B.V. All rights reserved.