[Position of NSAIDs in causal factors of peptic ulcer].

The cause of peptic ulcer is classified into five categories; infectious, drug-induced, hyperacidic, secondary, and idiopathic. Among these factors, H. pylori infection and non-steroidal anti-inflammatory drugs including aspirin (NSAIDs) are most important for development of gastroduodenal ulcer. More than 95 percent of gastroduodenal ulcers are associated with H. pylori or NSAIDs. Therefore, the frequency of non-H. pylori non-NSAIDs ulcer is very low. NSAIDs have the effect to inhibit synthesis of cyclooxygenase-1 (COX 1) and COX-2. This inhibitory action induces analgesic and anti-inflammatory effects. On the other hand, inhibitory action for COX-1 reduces the production of prostaglandin that is related to protective effect for gastrointestinal mucosa. Its mechanism is able to induce gastroduodenal ulcer. Since the elderly population in Japan is rising, the number of patients who need NSAIDs treatment is expected to increase in near future.