Cox-2 Inhibitors Dilemma: What Patients Should Do (cont.)

What's so special about COX-2 inhibitors?

COX-1

Cyclooxygenase-1 (COX-1) is an enzyme that is normally present in a variety of areas of the body, including sites of inflammation and the stomach. The COX-1 enzyme of the stomach produces certain chemical messengers (called prostaglandins) that ensure the natural mucus lining, which protects the inner stomach. Common anti-inflammatory drugs, like aspirin or ibuprofen, block the function of the COX-1 enzyme along with another enzyme, COX-2 (described below). With these traditional antiinflammatory drugs, inflammation is reduced by blocking Cox-2, but the protective mucus lining of the stomach is also reduced because Cox-1 is blocked, which can cause stomach upset, ulceration, and bleeding from the stomach and intestines.

COX-2

Another enzyme, cyclooxygenase-2 (COX-2), also produces these chemical messenger molecules, but the COX-2 enzyme is located specifically in areas of the body that are responsible for inflammation and not in the stomach. When the COX-2 enzyme is blocked, inflammation is reduced. Since the COX-2 enzyme does not play a role in the normal function of the stomach, medications that selectively block COX-2 do not present the risk of injuring the stomach that medications also blocking COX-1 can.

Newly developed drugs that selectively block the COX-2 enzyme are called COX-2 inhibitors. Blocking this enzyme impedes the production of the prostaglandins that cause the pain and swelling of arthritis inflammation. The common anti-inflammatory drugs (like aspirin, ibuprofen, and naproxen) are all non-selective and act by blocking the action of both the COX-1 and COX-2 enzymes.

The COX-2 inhibitors represent a newer class of anti-inflammatory drugs that do not affect COX-1, but selectively block only COX-2. This selective action provides the benefits of reducing inflammation without the increased risk of stomach irritation, ulceration, and bleeding. A major advantage of the COX-2 inhibitors over traditional non-selective COX-1 and COX-2 NSAIDs (nonsteroidal anti-inflammatory drugs) lies in the fact that they are easier on the stomach. Therefore, they are generally considered safer for patients with a history of stomach (gastrointestinal) problems. Another particular advantage of COX-2 inhibitors is that they do not impair the normal function of an important blood clotting element called platelets. As a result, they may be used in patients taking blood thinning medications, such as warfarin (Coumadin), and they may be used in and around surgical procedures without an increased risk of bleeding.