Cox-2 Inhibitors

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Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

• What are NSAIDs and what are Cox-2 inhibitors?
• What is the basic difference between traditional NSAIDs and COX-2 inhibitors?
• What are side effects of COX-2 inhibitors?
• Which COX-2 inhibitors are available in the United States?

What are NSAIDs and what are Cox-2 inhibitors?

Nonsteroidal antiinflammatory drugs (NSAIDs) are a class of drugs that reduce inflammation but are different from steroids, another class of drugs that also reduces inflammation. NSAIDs reduce pain, fever, and swelling and are commonly prescribed for the inflammation of the joints (arthritis) and other tissues, such as in tendinitis and bursitis. Examples of NSAIDs include:

• aspirin,
  
  
• indomethacin (Indocin),
  
  
• ibuprofen (Advil, Motrin),
  
  
• naproxen (Naprosyn),
  
  
• piroxicam (Feldene), and
  
  
• nabumetone (Relafen).

NSAIDs are used frequently by millions of individuals for treatment of pain, fever and swelling caused by inflammatory conditions as well as for pain alone. NSAIDs work by blocking the production of prostaglandins, chemical messengers that often are responsible for the pain and swelling of inflammatory conditions.

Prostaglandins are made by two different enzymes, cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). The prostaglandins made by the two different enzymes have slightly different effects on the body. COX-2 inhibitors are NSAIDs that selectively block the COX-2 enzyme and not the COX-1 enzyme. Blocking this enzyme impedes the production of prostaglandins by the COX-2 enzyme that often cause the pain and swelling of inflammation and other painful conditions. Because they selectively block the COX-2 enzyme and not the COX-1 enzyme, these drugs are uniquely different from traditional NSAIDs which usually block both COX-1 and COX-2 enzymes.

COX-2 inhibitors are used for treating:

• colorectal polyps (because they have effects on abnormally dividing cells such as those of precancerous colorectal polyps),
  
  
• menstrual cramps,
  
  
• sports injuries,
  
  
• osteoarthritis, and
  
  
• rheumatoid arthritis.

What is the basic difference between traditional NSAIDs and COX-2 inhibitors?

COX-1 is an enzyme which is normally present in a variety of tissues in the body, including sites of inflammation and the stomach. Some of the prostaglandins made by COX-1 protect the inner lining of the stomach. Common NSAIDs such as aspirin block both COX-1 and COX-2 (see below). When the COX-1 enzyme is blocked, inflammation is reduced, but the protection of the lining of the stomach also is lost. This can cause stomach upset as well as ulceration and bleeding from the stomach and even the intestines.

The other cyclooxygenase, COX-2, also produces prostaglandins, but the COX-2 enzyme is located specifically in areas of the body that commonly are involved in inflammation but not in the stomach. When the COX-2 enzyme is blocked, inflammation is reduced; however, since the COX-2 enzyme does not play a role in protecting the stomach or intestine, COX-2 specific NSAIDs do not have the same risk of injuring the stomach or intestines.