Release of a Water-Soluble Drug from a Wax Matrix Timed-Release Tablet

The purpose of this work was to characterize the release of drug from a wax matrix tablet under relatively mild agitation conditions. It was found that phenylpropanolamine hydrochloride was released from a typical wax matrix by a diffusion mechanism. After an initial rapid release of drug from the tablet, the amount dissolved was proportional to the square root of time. The advance of the solvent front into the tablet matrix was also proportional to the square root of time. Compression force was not a major factor affecting drug release. Data on drug release from a single tablet face compared to release from a totally exposed tablet indicated that drug release is proportional to the total surface area.