This new generation non-steroidal
anti-inflammatory drugs (NSAIDs) are known as Coxibs. Although these drugs have a lower risk of gatro-intestinal side-effects and are regarded as safer than the traditional NSAIDs in this regard, Vioxx was pulled from market on 1 October 2004. Merck, the maker of the popular arthritis drug Vioxx, is removing it from markets worldwide after a new study found that long-term users face increased risks for heart attack and stroke.
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Coxibs are often used to relieve osteoarthritis pain, pain after dental or orthopaedic surgery, and muscle pain.
What is the difference between Coxibs and the other
NSAIDs? Most NSAIDs (such as ibuprofen) simultaneously inhibit two forms of
enzymes, namely cyclo-oxygenase 1 and 2, or COX-1 and COX-2.
These enzymes control the production of a group of chemicals, called prostaglandins, when a joint or tissue becomes inflamed. High activity of these enzymes
and prostaglandins are associated with severe inflammation, redness, swelling and pain.
NSAIDs lower the activity of both enzymes, thereby reducing the production of pro-inflammatory prostaglandins. Unfortunately, they also reduce the production of prostaglandins needed to protect the stomach lining.
Newer COX-2 specific NSAIDs, such as rofecoxib (Vioxx®) and celecoxib (Celebrex®), blocks only the COX-2 enzyme – the one specifically regulating the activity of the
prostaglandins involved in inflammation. The stomach-protecting COX-1 enzyme is not targeted at recommended doses.
Safer?
Coxibs are generally safer than NSAIDs, because they:
have a lower risk of damaging the stomach lining and causing bleeding;
have a lower risk of renal disease than other NSAIDs;
have no effect on bleeding time and platelet function. Coxibs have no anti-clotting or clotting action, and will not increase any risk of bleeding. They also have no effect on the activity of low-dose aspirin. People taking a low dosage of aspirin daily, can take Coxibs without any increased risk of bleeding;
can be taken with or without food and either before or after a meal, since a standard meal has no effect on on the extent and rate of absoption of these newer drugs.
Hoewever, a new two-year-study found that long-term users face increased risks for heart attack and stroke.
Who should not take these medication?
Pregnant and breastfeeding women, as well as children, should not take coxibs as the safety and efficacy have not been established in these cases. People with uncontrolled hypertension, uncontrolled heart failure, knwon heart disease, kidney or liver disease, bleeding from the stomach lining, a stomach or duodenal ulcer, and patients who are hypersensitive to NSAIDs, should not take these drugs.
Patients with signs of asthma, acute hayfever, or a allergic reaction to any other NSAID or aspirin should avoid Coxibs as well.
Patients using the drug warfarin, or any other prescription medication with an anti-clotting action, should be monitored because NSAIDs may prompt reversal of warfarin's action, resulting in clot formation.
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