Fenamic acid is a derivative of anthranilic acid,[12]:235 which in turn is a nitrogen isostere of salicylic acid, which is the active metabolite of aspirin.[12]:235 Several non-steroidal anti-inflammatory drugs, including mefenamic acid, tolfenamic acid, flufenamic acid, and meclofenamic acid are derived from fenamic acid or anthranilic acid and are called "anthranilic acid derivatives" or "fenamates".[13]:17