A system for controlled release, site-specific delivery of therapeutic agents, particularly myocardial agents such as antiarrhythmic agents, comprises a biocompatible polymeric matrix with an incorporated therapeutic agent for direct placement at the epicardium. Advantageously, the dosage form can be fabricated in such a manner as to tailor the release characteristics as required by the nature of the physical condition desired to be treated. In a specific illustrative embodiment, lidocaine, an antiarrhythmic depressant, is incorporated in polyurethane by a unique method which permits drug-loading of the polymeric matrix from about 5% up to 40% by weight, with about 25% to 30% in a preferred embodiment. A novel FeCl.sub.3 catalyst causes the polyurethane to polymerize despite the presence of drug in the polymeric matrix mixture.