Cyclooxygenase-2 (COX-2) inhibitors are a type of nonsteroidal anti-inflammatory drug (NSAID) that specifically blocks COX-2 enzymes. Nonsteroidal anti-inflammatory agents (usually abbreviated to NSAIDs) are a group of medicines that relieve pain and fever and reduce inflammation.
There are two main types of COX enzymes: COX-1 and COX-2. Both types produce prostaglandins; however, the main function of COX-1 enzymes is to produce baseline levels of prostaglandins that activate platelets and protect the lining of the gastrointestinal tract, whereas COX-2 enzymes are responsible for releasing prostaglandins after infection or injury. Prostaglandins have several different effects, one of which is to regulate inflammation.
By specifically only blocking COX-2 enzymes, COX-2 inhibitors relieve inflammation and pain with less adverse gastrointestinal effects than NSAIDs that inhibit both COX-1 and COX-2 enzymes. However, they are not devoid of gastrointestinal effects entirely, and their use (like all NSAIDs) has been associated with a higher risk of stroke and heart attack.
What are COX-2 inhibitors used for?
COX-2 inhibitors may be used to treat mild-to-moderate pain or inflammation caused by a wide range of conditions such as:
- Ankylosing spondylitis
- Hereditary polyps of the colon
- Juvenile rheumatoid arthritis in children aged from two years
- Menstruation
- Osteoarthritis.
COX-2 inhibitors may also be used to treat acute pain such as that experienced with sports injuries.
What are the differences between COX-2 inhibitors?
Celecoxib is currently the only COX-2 inhibitor available in the U.S, following the withdrawal of rofecoxib in 2004 and valdecoxib in 2005 due to an excessive increase in the risk of heart attack and stroke. Celecoxib tends to be more expensive than nonselective NSAIDs; however, it is available as a generic.
Celecoxib is considered as effective as other NSAIDs (such as ibuprofen, diclofenac, and naproxen) at reducing pain and inflammation, but the risk of gastrointestinal side effects is reduced. It is associated with a higher risk of cardiovascular events; however, this risk is similar to that of nonselective NSAIDs. At higher dosages, celecoxib suppresses COX-1 enzymes to some extent.
|
Generic name |
Brand name examples |
|
Celecoxib |
Celebrex |
|
Etoricoxib |
Not approved in the U.S. |
|
Lumiracoxib |
Not approved in the U.S. |
|
Rofecoxib, Valdecoxib |
Withdrawn because of safety concerns |
Are COX-2 inhibitors safe?
COX-2 inhibitors can increase the risk of having a fatal heart attack or stroke. The risk increases the higher the dosage and the longer the duration of treatment. Celebrex should not be used in people with certain heart conditions, with a previous history of stroke, or after heart bypass surgery (coronary artery bypass graft, or CABG).
Although celecoxib is associated with a lower risk of gastrointestinal(GI) side effects it should be used with caution in people with active GI ulceration or bleeding or inflammatory bowel disease. Elderly people or those taking other medicines that irritate the stomach are more likely to experience life-threatening GI side effects, such as stomach or intestinal bleeding.
COX-2 inhibitors may also delay the ability of the blood to clot, increasing the risk of hemorrhage. COX-2 inhibitors are not approved for use in children younger than two years old.
Most NSAIDs, including celecoxib, should not be taken during the last three months of pregnancy or while breastfeeding except on a doctor’s advice.
For a complete list of side effects, please refer to drug monograph for celecoxib.
What are the side effects of COX-2 inhibitors?
COX-2 inhibitors are more likely to cause side effects when used at higher than recommended dosages for long periods of time.
Gastrointestinal side effects that may occur include bloating, diarrhea, constipation, irritation of the lining of the stomach, nausea or vomiting. Headache and dizziness have also been reported with COX-2 inhibitors.
COX-2 inhibitors may also affect kidney function and reduce how quickly blood flows through the kidneys. They may cause retention of sodium and water which can lead to edema and high potassium levels. Occasionally, they may cause more serious damage to the kidneys.
Taking COX-2 inhibitors increases your risk of cardiovascular thrombotic events such as a heart attack or stroke. Other heart-related side effects such as high blood pressure, congestive heart failure, and palpitations have also been reported.
For a complete list of side effects, please refer to drug monograph for celecoxib.
