The preparation of hard composites by the free radical polymerization at room temperature of a blend of beta-tricalcium phosphate, poly(ethyl methacrylate), methyl methacrylate monomer and fosfosal(R) is described. After the immersion of the composites in a buffered solution, the controlled release of an analgesic drug, fosfosal, is observed. The ceramic component participates actively in the control of the release of the drug by means of the formation of a bridging complex with the fosfosal, as demonstrated by FTIR studies.