Clinical pharmacology of lumiracoxib, a second-generation cyclooxygenase 2 selective inhibitor

Abstract

Although highly selective cyclooxygenase (COX)-2 inhibitors have been shown to be less toxic to the gastrointestinal tract than conventional non-steroidal anti-inflammatory drugs (NSAIDs), their overall safety profile is questioned. Since different selective COX-2 inhibitors were found to be associated with increased cardiovascular thrombotic events, the thrombotic hazard may be a class effect. Furthermore, warnings have been issued regarding serious skin and hypersensitivity reactions associated with valdecoxib. Lumiracoxib is a novel COX-2 selective inhibitor (coxib) with improved biochemical selectivity over that of currently available coxibs. It is structurally distinct from other drugs in the class and has weakly acidic properties. Clinical studies support a once-daily dosing regimen, despite its relatively short plasma elimination half-life (3 - 6 h). In randomised, controlled clinical trials, lumiracoxib 100 - 200 mg/day has been shown to be superior to placebo in patients with symptomatic osteoarthritis, with clinical efficacy similar to diclofenac 150 mg/day, celecoxib 200 mg/day or rofecoxib 25 mg/day. Furthermore, lumiracoxib 200 - 400 mg/day appeared to be effective in patients with rheumatoid arthritis. In patients with acute pain related to primary dysmenorrhoea, dental or orthopaedic surgery, lumiracoxib 400 mg/day was found to be at least as effective as standard doses of traditional NSAIDs and other coxibs. Endoscopic studies have indicated that lumiracoxib is associated with a rate of gastroduodenal ulcer formation that is significantly lower than with ibuprofen and does not differ from celecoxib. In the Therapeutic Arthritis Research and Gastrointestinal Trial, which enrolled 18,325 patients with osteoarthritis, the cumulative 1-year incidence of ulcer complications (primary end point) was significantly reduced by approximately threefold on lumiracoxib 400 mg/day compared with naproxen 1000 mg/day or ibuprofen 2400 mg/day (0.32 versus 0.91%). Reduction in ulcer complications was more pronounced in the population not taking low-dose aspirin (0.2 versus 0.92%, respectively). Conversely, the gastrointestinal advantage of lumiracoxib was abrogated in patients receiving low-dose aspirin (0.69 versus 0.88%, respectively, p = 0.49). Regarding cardiovascular events contributing to the trialists' composite end point (myocardial infarction, stroke or cardiovascular death), there was no significant difference between lumiracoxib (0.65%) versus combined comparator NSAIDs (0.55%). Similarly, no significant difference was recorded in rates of myocardial infarction (clinical and silent) between the lumiracoxib (0.25%) and the combined NSAID (0.19%) treatment groups. Liver function test abnormalities were more frequent with lumiracoxib (2.57%) than with the comparator NSAIDs (0.63%). Whether or not this would result in an increased risk of clinical hepatitis in the real world setting is unforeseeable.