Niflumic acid is a drug used for joint and muscular pain. It is categorized as an inhibitor of cyclooxygenase-2. In experimental biology, it has been employed to inhibit chloride channels. It has also been reported to act on GABA-A and NMDA channels and to block T-type calcium channels. Niflumic acid is a drug used for joint and muscular pain. It is categorized as an inhibitor of cyclooxygenase-2. In experimental biology, it has been employed to inhibit chloride channels. It has also been reported to act on GABA-A and NMDA channels and to block T-type calcium channels.