COX

Cyclooxygenase or COX is a naturally occurring enzyme involved in creating the prostaglandins involved in inflammation. Some painkillers, most obviously aspirin and ibuprofen, inhibit the action of COX and reduce inflammation. However, COX is also involved in the protection of the stomach lining, and COX inhibitors result in gastritis as a common side effect, newer painkillers target only the type of COX that affect inflammation, preventing the gastric upset.
Cyclooxygenase at Wikipedia
Category:Endocrinology