Erodible perforated coated matrix for extended release of drugs

A new oral modified release system exibiting an in vitro constant release rate has been designed and prepared. The system consists of an erodible matrix core with a central hole and is partially covered with an impermeable polymeric film. The perforated core is made of a low viscosity hydroxypropylmethylcellulose (HPMC); metoprolol tartrate and benfluorex were used as model drugs. The inner hole surface is the only releasing surface of the system. This system can be prepared by using both conventional tabletting and film coating processes.