Formulation and Evolution of Some Prolomced

Release kinetics of the prepared tablets obey the biphasic release in which the initial release follows a zero-order pattern while the steady state phase is in accordance with the matrix diffusion-controlled release pattern as well as the zero-order type Tablets made of ethyl cellulose-coated microcapsules show Bore rapid release rate than the corresponding tablets made Of microcapsules coated with Eudragit type of polymers, Indicating that the swelling properties of ethyl cellulose is much higher than that of methacrylates.There was a wide variation in the rate and extent of release between tablets compressed under high and low pressure levels. However, beyond a certain compressional force (intermediate pressure), no significant change in release behaviour was obtained. An exception was observed with tablets made of microcapsules coated with maleic anhydride-methyl vinyl ether copolymer, where there was no difference in release behaviour irrespective of the pressure applied during tableting.The use of the high pressure value did not result in breakage of microcapsules whose shells of polymer coats were recovered Intact after the end of dissolution experiment and release of all drug through the pores. This is supported by the observation that the drug release within the first 5 minuets was almost near the zero reading.