Antiarthritic — etoricoxib
Non-steroidal antiinflammatory drugs are widely used as analgesics, particularly in alleviating the symptoms of arthritis. However, their tendency to cause gastrointestinal side-effects means their use is limited in patients with a history of gastric disturbances, and care must be taken with extended use to prevent the development of ulcerative side-effects. The recent discovery that the enzyme cyclooxygenase exists in two forms led to the development of a group of drugs with lower side-effect profiles. COX-1 was found to be responsible for the gastroprotective effects, and COX-2 for the inflammation, so developing agents that act selectively as COX-2 inhibitors meant a group of drugs could be introduced for treating arthritis with fewer side-effects.
A further member of this class, etoricoxib, previously known as MK-663, is undergoing trials at Merck & Co for use as a treatment for osteoarthritis, rheumatoid arthritis and pain.1 Its efficacy and tolerability in the treatment of osteoarthritis of the knee were demonstrated in a multi-centre randomised triple-blind placebo-controlled trial. A total of 617 patients were given 5, 10, 30, 60 or 90mg of the drug once a day for six weeks. This was followed by an extension for eight weeks in 500 of the patients, and those patients previously given 5 or 10mg received 30mg etoricoxib or 150mg diclofenac. Substantially better pain relief was achieved in patients treated with etoricoxib, and it was well tolerated throughout the duration of the trial.2
Another trial looked at the drug as a single dose treatment for acute dental pain. Two hundred patients suffering moderate to severe pain were given one 120mg dose of etoricoxib, naproxen sodium (550mg) or paracetamol and codeine (600mg and 60mg), or placebo. Etoricoxib had the longest duration at over 24 hours, compared with 22 hours for naproxen and just over five hours for paracetamol and codeine. Etoricoxib was well tolerated, and had a similar analgesic activity to naproxen, but much better effectiveness than paracetamol and codeine.3
The drug is now undergoing Phase III trials to establish its effectiveness, safety and tolerability as an analgesic.