A gel formulation of the sodium salt of diclofenac, a nonsteroidal benzeneacetic acid derivative with analgesic, antipyretic and anti-inflammatory activities. Diclofenac binds to and chelates both isoforms of cyclooxygenase (COX-1 and-2), thereby blocking the conversion of arachidonic acid (AA) to pro-inflammatory prostaglandins. This agent may also inhibit lipoxygenases, resulting in the inhibition of pro-inflammatory leukotriene synthesis from AA. Check for active clinical trials using this agent. (NCI Thesaurus)