What Are Cyclooxygenase Inhibitors?

Cyclooxygenase (COX) is a protein in the body that helps to produce prostaglandins and other compounds in the body that are involved in the inflammatory response. One drug class, cyclooxygenase inhibitors, prevents COX from forming these products, thereby dampening the inflammation and sensation of pain that can occur during disease or injury. This mechanism not only accounts for the uses of cyclooxygenase inhibitors, but also their potential adverse events. Certain drugs in this class, such as aspirin, also have unique aspects that provide them with uses other than pain relief.

Two forms of the COX enzyme exist in the body, known as COX-1 and COX-2. Of these, COX-2 seems to create the majority of the products involved in inflammation, and prostaglandins made by both variations of this enzyme also play a role in protecting the stomach lining from being damaged by acids. Many cyclooxygenase inhibitors, such as aspirin, ibuprofen, and acetaminophen, reduce the efficacy of both COX types. In doing so, these drugs can effectively alleviate inflammation, pain, and fever for many individuals. They also prevent prostaglandins in the stomach from being produced, however, which can lead to gastrointestinal problems like pain, nausea, and even tissue damage when taken in high doses.

Among the commonly used cyclooxygenase inhibitors, one drug, aspirin, has somewhat unique properties. Most COX inhibitors reversibly affect these enzymes, meaning that these proteins continue to create prostaglandins after these medications are taken, albeit at a reduced rate. Aspirin's inhibition of COX-1 is irreversible, however, effectively preventing these proteins from operating. In doing so, it can function as an anti-platelet drug, because some COX-1 products can cause blood cells known as platelets to bind to one another abnormally in some conditions. Other cyclooxygenase inhibitors do not generally have this quality, however.

Newer types of cyclooxygenase inhibitors have been developed in an attempt to provide beneficial anti-inflammatory effects, while reducing the likelihood of gastrointestinal side effects. These compounds are classified as COX-2 inhibitors, as they selectively affect COX-2 enzymes, while allowing COX-1 to continue to function normally. Certain adverse events are less common with these drugs, particularly gastric ulcers.

Other unwanted side effects that occur with less selective COX inhibitors can arise when taking these compounds, however. In particular, COX-2 inhibitors, as well as general COX inhibitors, can lead to hormone imbalances, because some processes in the body require prostaglandins to regulate them. Rarely, these imbalances can lead to results as severe as heart attacks and strokes. Kidney damage may also occur among some individuals taking these drugs, because they can sometimes inhibit the flow of blood to these organs.