Proquazone (RU 43-715) is a chemically distinctive non-steroidal anti-inflammatory agent (NSAID) and an inhibitor of calcium sensing receptor (CaSR) . unlike most other NSAIDs, Proquazone does not have a free acid group in its structure. Proquazone may inhibit or arrest progression of bone erosions. Proquazone is an orally active anti-inflammatory, analgesic and anti-pyretic agent[1].