A gel formulation has been developed which provides high loading, e.g., between about 5% and about 50% wt/wt agent/total gel weight, of a wide range of agents, especially amine-containing compounds such as local anesthetic agents that are known to be difficult to encapsulate, and which adhere to charged surfaces. Examples of pharmaceutically important amines include anesthetics, such as lidocaine. Tuning the ionic strength of an aqueous medium during preparation, suspension, and dialysis purification of the hydrogel composition allows for retention and/or control of agent loading contents, as well as a high capacity for adhesion to charged surfaces mimicking inflamed tissue. In some instances, the rheological properties of the gel can be tuned such as to impart thixotropic properties to the gels formed.
