Summary: Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world. As a group, NSAIDs are very eff ective anti-inflammatory, antipyretic and analgesic agents. Although many different NSAIDs are used on the world market, they all share the same basic mechanism of action of inhibiting cyclooxygenase (COX). The introduction of selective COX-2 inhibitors improved the efficacy and safety of NSAIDs.