Propranolol hydrochloride sustained release capsules prepared from pellets coated with the mixtures of ammonio methacrylate copolymer and ethylcellulose using fluidized bed technique

Abstract

Propranolol hydrochloride pellets were prepared using extrusion and spheronization techniques. Core pellets were coated with the mixtures of ammonio methacrylate copolymer and ethycellulose in various ratios which were implemented as a film coatings to control the release of the drug. A mixture of acetone and isopropyl alcohol in a ratio of 1:1 was employed as a cosolvents for coating solution. Pellets were coated using a fluidized bed technique of Wurster type. Physical characteristics and drug release characteristics of uncoated and coated pellets were investigated. Ethylcellulose gave a rough and porous surface coating film. Nevertheless, when the ethylcellulose film was mixed with either Eudragit RL100 or Eudragit RS100, the coating surface becames smoother. Increasing the amount Eudragit improved the smoothness of the coating surface. Consequently, with the higher coating levels the thicker film layer was obtained. The drug release characteristics of coated pellets were affected by dissolution mediums employed. In general, a release rate of coated pellets in an acidic medium was faster than in an alkali medium. At higher coating levels, the release of the drug from the pellets was more retarded. The ratio of polymers affects the drug release characteristics, resulting in the following scenarios: increasing percent of ethylcellulose, decreasing the drug release, increasing either Eudragit RL100 or Eudragit RS100, increasing the drug release. In this study, the coated pellets of various formulations which provided suitable release rates were selected and combined to formulate sustained release propranolol hydrochloride capsules of 24 hour type that could meet the USP XXIII specification. The release profiles of developed formula were comparable to the release characteristic of Inderal LA160, a wellknown commercial product.