An investigation of the release properties of a cationic drug from a hydrophobic polyanhydride matrix as a function of dissolution medium

摘要

The dissolution of a drug delivery system consisting of gentamicin sulfate in a hydrophobic polyanhydride matrix has been examined. The in vitro release of gentamicin is a function of the composition of the dissolution medium, with slower release in pH 7.4 buffer than in unbuffered water. This is consistent with an anion exchange taking place under conditions in which carboxylate polymer chain-ends form a poorly soluble salt with gentamicin, and sulfate is released into solution. Results of additional experiments probing this model are discussed.