Nonsteroidal, antiinflammatory drug-induced gastrointestinal injuries and related adverse reactions: Epidemiology, pathogenesis and management

A large proportion of the population all over the world consumes acetylsalicylic acid (ASA: aspirin) or other nonsteroidal, antiinflammatory drugs (NSAIDs). This is associated with a considerable morbidity and mortality. Elderly patients, patients with prior history of peptic ulcer disease (PUD) or its complications, those who require high doses of NSAIDs and those undergoing concomitant therapy with corticosteroids or anticoagulants, are at particularly high risk of developing gastroduodenal injuries and related adverse reactions. Gastroduodenal mucosal injuries induced by NSAIDs vary from subtle microscopic to gross macroscopic changes including ulcers. These injuries are induced by both topical and systemic actions of NSAIDs. Inhibition of gastroduodenal cyclooxygenase (COX) enzyme by NSAIDs is considered to be a major pathogenetic factor. Reactive oxygen species (ROS) appear also to play a significant role in the pathogenesis of mucosal injury. Withdrawal of NSAIDs is preferably the first therapeutic option; however, it is not feasible in the majority of patients. Therefore, several drugs including antisecretory drugs (ASDs-proton pump inhibitors and Histamine-2 receptor antagonists) and misoprostol, a prostaglandin analog are used for the prevention and treatment of NSAID-induced gastroduodenal injuries. Among ASDs, proton pump inhibitors (PPIs) are the most commonly used drugs. The antiulcerogenic effect of PPIs is similar to that of misoprostol and superior to standard doses of histamine-2 receptor antagonists (H2-RAs). The adverse effects of m,isoprostol such as diarrhea, abdominal pain, nausea, flatulence, headache, dyspepsia, vomiting, constipation, abortifacient and teratogenicity limit its general use. Aside from their antisecretory action, PPIs also possess an antioxidative effect. PPI maintenance is recommended in chronic NSAID treatment in those with an increased risk of complications and is more effective than Helicobacter pylori eradication. Low PPI dosage maintenance is as effective as a standard dosage regimen. The effect of H. pylori eradication remains controversial. It is advocated in naοve NSAID users, in chronic users with recent ulcer or ulcer complications and in those with an increased risk of ulcer and ulcer complications. In addition, some herbs have shown inhibition of gastric mucosal damage experimentally induced by necrotizing agents through their antisecretory and antioxidant properties