Diclofenac, a phenylacetic acid derivative is a prototypical NSAID. It has potent anti-inflammatory, analgesic and antipyretic actions. It reversibly inhibits the enzyme, cyclooxygenase, thus resulting in reduced synthesis of prostaglandin precursors.
The anti-inflammatory effects of diclofenac are believed to be due to inhibition of both leukocyte migration and the enzyme cylooxygenase (COX-1 and COX-2), leading to the peripheral inhibition of prostaglandin synthesis. As prostaglandins sensitize pain receptors, inhibition of their synthesis is responsible for the analgesic effects of diclofenac. Antipyretic effects may be due to action on the hypothalamus, resulting in peripheral dilation, increased cutaneous blood flow, and subsequent heat dissipation.