Process and formulation variables affecting the drug release from chlorpheniramine maleate-loaded beads coated with commercial and self-prepared aqueous ethyl cellulose pseudolatexes

Abstract

Chlorpheniramine maleate-loaded nonpareil seeds were coated in a fluidized bed with a commercial ethyl cellulose pseudolatex, Aquacoat, and ethyl cellulose pseudolatexes prepared by a microfluidization-solvent evaporation technique in order to investigate the effect of process variables (coating temperature, curing temperature and time) and formulation variables (surfactant concentrations) on the drug release in simulated gastric and intestinal fluids. Although curing and coating conditions did not affect the drug release in simulated gastric juice, dramatic increases in drug release were seen in simulated intestinal fluid with incompletely cured beads. The presence of the anionic surfactant, sodium lauryl sulfate, in the coating caused the pH-dependent drug release from ethyl cellulose pseudolatex-coated beads. The release from beads coated with surfactant-free pseudolatexes was insensitive to the pH of the dissolution medium. With cured beads, the faster initial drug release in simulated intestinal fluids was attributed to the better wetting of the beads, as indicated by contact angle measurements. The addition of cetyl alcohol as a cosurfactant decreased the drug release and pH sensitivity of the film.