text: Lumiracoxib is unique amongst the coxibs in being a weak acid. It was developed for the treatment of osteoarthritis, rheumatoid arthritis and acute pain. The acidic nature of lumiracoxib allows it to penetrate well into areas of inflammation. It has shown to be rapidly and well absorbed, with peak plasma concentration occurring in about 1–3 hours. A study showed that when a subject was given 400 mg dose, the amount of unchanged drug in the plasma 2.5 hours postdose suggest a modest first pass effect. The terminal half-life in plasma ranged from 5.4 to 8.6 hours (mean =6.5 hours). The half-life in synovial fluid is considerably longer than in plasma, and the concentration in synovial fluid 24 hours after administration would be expected to result in a substantial COX-2 inhibition. This fact can explain why some users may suffice with once-daily dosage despite a short plasma half-life. The major plasma metabolites are 5-carboxy, 4’-hydroxy, and 4’-hydroxy-5-carboxy derivatives. Lumiracoxib is extensively metabolized before it is excreted, and the excretion routes are in the urine or feces. Peak plasma concentrations exceed those necessary to maximally inhibit COX-2, and that is consistent with a longer pharmacodynamic half-life. In vitro lumiracoxib has demonstrated a greater COX-2 selectivity than any of the other coxibs.