Modeling of drug release from erodible tablets

A general mathematical model was developed to describe drug release from erodible tablets undergoing surface erosion. The model (which is based on the Hopfenberg equation) takes into account the three dimensions of a tablet dosage form. The model enables the characterization of the release kinetics by one or two erosion rate constants depending on the hydrodynamic conditions of the system. The model can be used to compare the release rates of the drug within different batches produced under different conditions. The model was utilized to evaluate some factors affecting the release rate from erodible tablets consisting of hydroxypropyl methylcellulose and amoxicillin. The release data of amoxicillin measured from the whole tablet followed the equation developed. Amoxicillin release data measured from the planar surface of the tablet appeared to follow zero-order kinetics as predicted by theory for drug release from an erodible device maintaining constant surface area with time.