Nonsteroidal anti-inflammatory drugs (NSAIDs)

Medications that relieve INFLAMMATION by suppressing the action of PROSTAGLANDINS, which are responsible for the inflammatory response. There are several types of prostaglandins, most of which are biochemical messengers that have numerous roles in routine cellular activity. Other prostaglandins are the agents of inflammation. The prostaglandins that incite inflammation do so by summoning numerous other biochemicals to the site of an injury, ultimately resulting in fluid accumulation and swelling at the site.

Three NSAIDs are available in over-the-counter (OTC) preparations as well as stronger prescription-only products: ibuprofen, naproxen, and ketoprofen. All other NSAIDs available in the United States (except aspirin) require a doctor’s prescription.

aspirin diclofenac
diflunisal etodolac
fenoprofen flurbiprofen
ibuprofen indomethacin
ketoprofen meclofenamate
mefenamic acid meloxicam
naproxen oxaprozin
nabumetone piroxicam
sulindac tolmetin

How These Medications Work

NSAIDs work by blocking the action of cyclooxygenase (COX), the enzyme that allows cells to convert arachidonic acid (a dietary fatty acid found in meats) into prostaglandins. The two main forms of COX are cyclooxygenase 1 (COX-1) and COX-2. Many types of cells in the body contain COX-1, but COX-2 occurs primarily in mast cells. COX-1 is responsible for prostaglandin synthesis for these roles. Prostaglandins are also the agents of inflammation. Mast cells contain COX-2, which enables them to synthesize large quantities of prostaglandins during an IMMUNE RESPONSE.

Most NSAIDs are nonselective; they block both COX-1 and COX-2. Though this action effectively relieves inflammation and associated symptoms (such as PAIN and FEVER), it also interferes with various general functions of cells throughout the body. One consequence of this interference is STOMACH upset. Gastric cells contain an abundance of COX-1 and synthesize forms of prostaglandin that help protect the lining of the stomach. Suppressing COX-1 activity reduces this protection. As well, the NSAID preparations are generally acids, which further irritate stomach tissues.

Therapeutic Applications

Doctors prescribe or recommend NSAIDs for pain relief and to reduce fever and inflammation, such as from musculoskeletal injuries. NSAIDs have widespread therapeutic applications and are among the most commonly used medications in the United States. Though all NSAIDs share the same mechanism of action, some are more effective for specific conditions. Ibuprofen, naproxen, and ketoprofen are effective for general relief. Other NSAIDs more aggressively block COX, making them especially useful for moderate OSTEOARTHRITIS, RHEUMATOID ARTHRITIS, and inflammatory disorders such as SYSTEMIC LUPUS ERYTHEMATOSUS (SLE).

The original NSAID is aspirin, first isolated and used as a therapeutic preparation in the late 1800s. Aspirin, a nonselective COX inhibitor, remains the most commonly used medication in the world, primarily for its ability to relieve pain and fever. In the 1970s cardiologists began recommending daily aspirin for people at high risk for HEART ATTACK. During an inflammatory response prostaglandins combine with other substances to make the surfaces of platelets (clotting cells) sticky. This encourages PLATELET AGGREGATION, the first step of COAGULATION (clot formation). Blocking prostaglandin synthesis reduces the likelihood for BLOOD clots to form in the blood vessels. This effect is unique to aspirin among the NSAIDs; other NSAIDs have only very mild antiplatelet effect.

In the late 1990s and early 2000s several selective COX-2 NSAIDs became available. These COX-2 inhibitors had the ability to selectively target and block only COX-2, allowing COX-1-mediated prostaglandin synthesis to continue unimpeded while preventing COX-2-mediated synthesis to reduce inflammation. However, widespread use of COX-2 inhibitors revealed that these medications carried increased risk for heart attack, and several were withdrawn from the US market. Nonselective (classic) NSAIDs do not appear to carry the same risk, though may increase the risk for heart attack in people who have recently had OPEN HEART SURGERY.

People who have recently had OPEN HEART SURGERY or HEART ATTACK should check with their doctors before taking any nonsteroidal anti-inflammatory drug (NSAID) preparation, including cold and flu products that contain an NSAID.

Risks and Side Effects

The most common risk of NSAIDs is gastric upset and PEPTIC ULCER DISEASE. Extended use of an NSAID diminishes the amount of prostaglandins in the stomach, reducing the ability of the gastric mucosa (stomach lining) to protect itself from the acid normally present in the stomach as well as the acid of the NSAID itself. Some NSAIDs have more of this affect. Other common side effects include allergic reaction and interaction with other drugs. NSAIDs interact with numerous drugs as well as with each other. TINNITUS (ringing in the ears) is an early indication of excessive NSAID consumption. Long-term, high-DOSE NSAID use can cause permanent kidney and LIVER damage and failure of these organs.


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