Abstract

Gastrointestinal side effects from nonsteroidal anti-inflammatory drugs (NSAIDs) result mainly from inhibition of the enzyme cyclooxygenase (COX)-1; it is responsible for the synthesis of prostaglandin E2, which leads to increased mucosal blood flow, increased bicarbonate secretion, and mucus production, thus protecting the gastrointestinal mucosa. In inflammation, COX-2 is induced, causing synthesis of the prostaglandins in conditions such as osteoarthritis and rheumatoid arthritis. Two NSAIDs (celecoxib and rofecoxib) with very high specificity for COX-2 and virtually no activity against COX-1 at therapeutic doses have been approved for clinical use. In trials of celecoxib and rofecoxib, only 0.02% of patients had clinically significant gastrointestinal bleeding, compared to a 1% to 2% yearly incidence of severe gastrointestinal side effects with NSAIDs. Our patient had arthritis of the hips and chronic atrial fibrillation and was on warfarin therapy for stroke prevention; less than a week after starting celecoxib therapy, gastrointestinal bleeding and hypoprothrombinemia occurred.