Development of theophylline sustained release granules coated by fluidized bed technique with poly (ethylacrylate methylmethacrylate) and ethylcellulose aqueous dispersions

Abstract

Theophyline granules of different sizes were coated with ethylcellulose aqueous dispersion (Surelease) or poly(ethylacrylate methylmethacrylate) aqueous dispersion (Eudragit NE 30D) containing cab-o-sil by fluidized bed technique. The physical properties of coated granules and sustained release characteristics from capsules containing coated granules were evaluated and compared to those of uncoated granules. All uncoated theophylline granules exhibited rough surface and irregular shape. The granules coated with Eudragit NE 30D exhibited surface than Surelease coated granules. Increasing the coating level increased the thickness of film, thus granules became slightly larger. Edge and corner were lower when coated. The angles of and the moisture contents of all granules were within the range of 30-35ํ and 0.74-0.86% respectively. Comparison of the percent compressibility and the flow rate between uncoated and coated granules of each size showed varied results. For Surelease film, the percent elongation at break and the percent water sorption were increased with the increasing of the percentage of dibutyl phthalate as plasticizer whereas the tensile strength were decreased. The release rate of the drug from capsules containing granules decreased when increasing the amount of aqueous polymeric dispersion. The type of aqueous polymeric dispersion affected the release of drug. Capsules containing larger granules exhibited slower release of drug than smaller granules. For similar of drug release, the amount of Eudragit NE 30D used in coating was higher than that of the Surelease. The drug release model from capusles containing granules fitted mostly to tha first -order model. Some formulations of coated granules exhibited drug release conformed to the USP.