Multilayer drug-coated cores: A system for controlling drug release

Abstract

The present study was undertaken to develop a new controlled release model system using multilayer coated granules prepared by consecutively spraying aqueous solutions of diphenhydramine · HCl, dissolved in methylcellulose (MC) of various viscosity grades, onto lactose granules in a fluidized bed. The in vitro drug release profiles of the coated product were shown to be a function of the polymer viscosity grade and the sequential order of application of the polymeric component layers on the lactose granules. The permutation and the mass fraction of the component layers on the multilayer coated granules could be altered to provide different drug release rates. Although the equilibrium hydration and swelling of each component layer influenced drug diffusion to some extent, the overall release was not entirely governed by it. The drug release profiles were also modulated by the dissolution characteristics, particularly the particle size of the recrystallized drug that is embedded in the polymeric coat. This approach on controlled-release provides an outline for further work in this field. © 1992.