Effect of surfactants on release of a highly water-soluble medicinal compound from an inert, heterogeneous matrix

The release from a matrix compressed from a physical mixture of procaine hydrochloride, chlorinated poly(propylene), lactose, and a surfactant was investigated. With nonionic and cationic surfactants incorporated in the matrix, the release of procaine hydrochloride was linearly related to the square root of time, and as the concentration of the surfactants increased, the release was faster. When an anionic surfactant (sodium lauryl sulfate) was incorporated in the matrix, the release of procaine hydrochloride was linearly related to the square root of time; however, the release pattern depended on the concentration of the anionic surfactant. As the concentration of sodium lauryl sulfate increased to 4%, the release progressively slowed to a minimum because of the formation of a poorly soluble complex between the cationic procaine and the anionic surfactant. As the concentration of anionic surfactant increased further, the release increased as the complex was micellarly solubilized.