Dual microcapsules: Preparations and in vitro release rate studies

Microcapsules are used especially to obtain sustained release dosage forms but also they are widely used to provide protection for the drug against atmospheric effects, to cover the unpleasent taste and to improve the stability etc. Dual-walled microcapsules are prepared to fulfil these aims in a greater extent. For example, to control the required drug release from microcapsules, to provide equal drug release according to time, to protect the drugs from the decomposition by sunlight or to give them a pearlized appearance. Generally some microcapsules, especially prepared with highly soluble drugs in water or acidic medium don't have satisfactory sustained release. Besides this, some microcapsules are not stable in intestinal medium. The aim of this study was to prepare dual microcapsules from the microcapsules mentioned above to provide appropriate sustained release action. Dual microencapsulation procedure could be used especially to obtain an appropriate sustained release action, to protect the sensitive microcapsules from decomposition by sunlight, to target the drugs according to the required medium and to cover the microcapsules for certain aims