Constant Release Rate from Inert, Heterogeneous Matrixes by Means of Position-Dependent Loading

Abstract

Approximately zero-order release of ephedrine hydrochloride and procaine hydrochloride was obtained from multiple-layered matrixes of hydrogenated castor oil containing various concentrations of the medicinal compound in each layer. For the examples presented, an apparent zero-order release was observed for the release of 50–90% of the medicinal compound.