新規経口抗凝固薬ダビガトラン

Dabigatran,a New Oral Anticoagulant

はじめに

　わが国では，経口投与可能な唯一の抗凝固薬としてワルファリンが実に半世紀以上にわたって用いられてきた。しかしながら，ワルファリンには血液凝固モニター，ビタミンK摂取制限，他剤との相互作用のチェックの必要性などの不便さがあり，脳出血への危惧と相まって，本来適応となるべき症例に投与されないことも多かった。

　最近，これらの不便さをすべて解消する経口投与可能な抗凝固薬として選択的なトロンビン阻害薬や凝固Xa因子阻害薬が次々と開発され，心房細動患者を対象として大規模なワルファリンとの比較試験が行われている。その先鞭をつけて直接的トロンビン阻害薬ダビガトラン（dabigatran）の臨床試験成績が昨年発表され，大きな注目を集めた。

Abstract

　Warfarin is underused because it has many disadvantages for clinical use despite it has been used more than a half century as an only oral anticoagulant.　Dabigatran is a direct thrombin inhibitor,which is not metabolized by cytochrome P450,and thus does not require blood coagulation monitoring or vitamin K intake limitation,or produce drug interaction.　RE-LY was a randomized controlled trial to prove non-inferiority of dabigatran to warfarin in 18,113 high risk patients with non-valvular atrial fibrillation.　The results showed that stroke or systemic embolism was less frequent in patients on 150 mg dabigatran,major hemorrhage was less frequent in patients on 110 mg dabigatran,and hemorrhagic stroke was less frequent in patients on both 110 mg and 150 mg dabigatran than in patients on warfarin.　Dabigatran is expected to be approved as a more effective and safer oral anticoagulant than warfarin for stroke prevention in patients with atrial fibrillation.　Randomized controlled trials of many factor Xa inhibitors in comparison with warfarin are also ongoing in patients with atrial fibrillation.