Coxibs and arthritis pain and inflammation
A class of medicines called COX-2 inhibitors, or coxibs, were created to help relieve the pain and inflammation of osteoarthritis and rheumatoid arthritis. The coxibs are said to be less likely to irritate the stomach or gut than some of the older anti-inflammatory drugs, such as aspirin and indomethacin.
Many people who take aspirin and other NSAIDs (non-steroidal anti-inflammatory drugs) for arthritis suffer from stomach and gastrointestinal upsets caused, or made worse, by their medicine. Unfortunately, this means that some people with osteoarthritis, rheumatoid or other types of arthritis, particularly those with stomach ulcers, are unable to take NSAIDs regularly to relieve joint pain and inflammation.
The COX-2 inhibitors, or coxibs, such as celecoxib (brand name Celebrex) and meloxicam (e.g. Mobic), are said to be safer on the stomach and gut than the older medicines.
To understand what makes the coxibs different from the older anti-inflammatory agents, you have to understand a little about the COX (cyclo-oxygenase) enzymes. There are two COX enzymes: COX-1 and COX-2.
Put simply, COX-1 is useful to the body and is partly responsible for maintaining the lining of the stomach. On the other hand, COX-2 is responsible for pain and inflammation in diseases such as arthritis.
NSAIDs work by blocking the effects of COX-2. Unfortunately, the older NSAIDs are also believed to block the beneficial effects of COX-1, and so increase the risk of stomach upsets and stomach ulcers. This is why many people who take aspirin to relieve inflammation in arthritis suffer from stomach irritation and sometimes even bleeding ulcers.
By contrast, the coxibs are selective NSAIDs. They can block the inflammatory effect of COX-2 but are believed to keep the protective effects of COX-1.
Effectiveness of coxibs
So are the COX-2 inhibitors as effective as the older anti-inflammatory medicines at relieving pain and inflammation in arthritis? Studies have shown that coxibs are equally as effective as some of the older agents for pain relief and relief of inflammation in osteoarthritis and rheumatoid arthritis.
Safety of coxibs
Studies have also shown that coxibs are associated with much lower rates of gastric ulcer and ulcer complications than older conventional NSAIDs. However, there may be an increased risk of cardiovascular events, such as heart attack and stroke, associated with the use of celecoxib in high doses or for long periods.
Who might benefit from the coxibs?
People with osteoarthritis or rheumatoid arthritis who are at risk of gastrointestinal complications or who have a history of peptic ulcer disease are the kind of people who might benefit from a COX-2 inhibitor. You can discuss the risks and benefits of treatment with coxibs with your doctor, who will be able to tell you whether or not they are suitable for you.
Who should avoid the coxibs?
People who are allergic to sulfonamides should avoid celecoxib, and people who have had severe asthma or an allergic reaction to NSAIDs should not take a coxib. Also, people who are at increased risk of cardiovascular disease, such as heart attack or stroke, generally should not take coxibs. Coxibs should be taken in the lowest dose that is effective, for the shortest time possible. They should not be taken in addition to other NSAIDs. Your doctor will be able to tell you whether or not coxibs are suitable for you.
Pain and inflammation in arthritisOsteoarthritisOsteoarthritis results from damage to cartilage, which is the soft spongy material which insulates joints. Cartilage forms a barrier between the 2 bones of a joint and stops them from grinding and scraping against each other. When the cartilage becomes thinner or damaged, extra bone forms at the edges of joints. Symptoms of osteoarthritis can be pain, swollen joints, stiffness in the morning and limited motion in joints.Rheumatoid arthritisIn rheumatoid arthritis, the joints become inflamed. Normal joints are surrounded by a membrane (the synovium), which produces a lubricating fluid called synovial fluid. In rheumatoid arthritis, the synovium that surrounds your joints becomes inflamed and more fluid is produced which swells the capsule that contains it, causing pain. As more blood flows to the area, the joint may feel warm to the touch. Nerve endings in the area are irritated by the inflammatory reaction and produce pain. Rheumatoid arthritis can make people feel generally ill, tired and run down, making it even harder to cope with the pain.
2. MayoClinic.com. Arthritis (updated 22 Jan 2011). http://www.mayoclinic.com/health/arthritis/DS01122 (accessed Mar 2011).
3. MayoClinic.com. Celecoxib (oral route) (updated 1 Nov 2010). http://www.mayoclinic.com/health/drug-information/DR601969 (accessed Mar 2011).
4. Day RO. The vascular effects of COX-2 selective inhibitors. Aust Prescriber 2004; 27: 142-5. http://www.australianprescriber.com/magazine/27/6/142/5/ (accessed Mar 2011).
5. Pfizer. Celebrex prescribing information. Accessed via eMIMS. Date of TGA approved information: 23/06/2010.
6. Boehringer Ingelheim. Mobic prescribing information. Accessed via eMIMS. Date of TGA approved information: 01/09/2009.