A device for delivery of a therapeutic agent to a surgical cavity, including: a porous, mucoadhesive, freeze-dried polymeric matrix having first and second opposed surfaces, the matrix formed by a composition including chitosan; a plurality of particles embedded within the matrix, the particles containing the therapeutic agent and having a coating around the therapeutic agent, the coating including chitosan; and an additive selected from the group consisting of a hydration promoter, a particle adhesion inhibitor, a particle aggregation inhibitor, and combinations thereof. The first surface of the matrix is configured to be applied to the surgical cavity; the device releases the particles through the first surface; the device is also sterilized and provides release of approximately 20% to 100% of the therapeutic agent within 20 minutes of application to the surgical cavity.