出血性小腸疾患の診断―潰瘍性病変─NSAIDs腸炎を中心に

Small Intestinal Mucosal Injury Induced by Non-Steroidal Anti-Inflammatory Drugs : Evaluation with Capsule Endoscopy and Treatment

要旨　カプセル内視鏡によりNSAIDs起因性小腸粘膜傷害の実態が明らかになりつつある．アスピリンを含むNSAIDsの常用患者の70％以上に，また通常型NSAIDsの2週間の内服で60％近い服用者に小腸の粘膜傷害が認められた．選択的COX-2阻害薬は短期的には小腸粘膜傷害の発生を軽減させるが，長期的には通常型NSAIDsと粘膜傷害の頻度に差がないという報告もあり，NSAIDs起因性小腸粘膜傷害の治療・予防薬が望まれる．近年，本邦でミソプロストールやレバミピドを用いてNSAIDs起因性小腸粘膜傷害の抑制効果を調べた研究が行われ有望な結果が得られた．今後，他の薬剤を含め投与法，投与量などの検討が望まれる．

　Epidemiological studies suggest that NSAIDs may increase the risk of lower gastrointestinal adverse events. Capsule endoscopy and double balloon endoscopy, advanced modalities that now allow for full investigation of the entire small intestine, have revealed that NSAIDs can cause a variety of abnormalities in the small intestine, such as ulcerations, perforation, bleeding, and diaphragm-like stricture. At the same time, capsule endoscopy studies have shown that even co-administration of proton pump inhibitors failed to prevent NSAID-induced small intestinal damage in up to 55％ of healthy volunteers. We also found small intestinal mucosal breaks in 60％ of Japanese male subjects who received NSAID and proton pump inhibitor therapy. Mucosal breaks induced by two weeks administration of NSAIDs were spontaneously cured three weeks later without any treatment. For the prevention of NSAID-induced small intestinal injury, several studies have already shown that omeprazole, a proton pump inhibitor, is not effective, while celecoxib, a selective COX-2 inhibitor, effectively reduces both the number of mucosal breaks per subject and the percentage of subjects with at least one mucosal break. Recently in Japan, misoprostol and rebamipide were investigated for the prevention of NSAID-induced small intestinal injury. As confirmed by capsule endoscopy, misoprostol and rebamipide may prevent NSAID-induced macroscopic damage throughout the small intestine.