スパルフロキサシン（スパラ），ステアリン酸エリスロマイシン（エリスロシン）併用によりQT延長，torsade de pointesを生じた1例

A Case of QT Prolongation with Torsade de Pointes during Oral Administration of Sparfloxacin and Ervthromycin

　71歳，女性．気管支炎にてエリスロマイシン投与2週間後，スパルフロキサシン（スパラ）の併用投与2日後にめまい，意識消失を起こし1995年4月20日当院紹介受診．心電図上QT延長（QTc 0.67秒），前胸部のT波陰転化，さらにtorsade de pointes（Tdp）の頻発がみられた．胸部X線写真上CTR 68％，心エコー図では左室駆出率70％と正常，軽度の心肥大と僧帽弁逆流を認めた。血液検査所見では腎機能，電解質は正常，軽度の貧血と肝酵素の上昇を認めた．薬剤によるQT延長を考え，スパルフロキサシン，エリスロマイシンを中止．Tdpは直流除細動で停止後，一時的ペーシングによって予防可能であった．その後QTcは徐々に短縮，第5病日にはTdpは消失した．スパルフロキサシン，経口エリスロマイシンともQT延長を起こしうるが，単剤投与でTdpを起こした報告は本邦にはなく，本例では両薬剤の併用によりTdpが起こったと考えられた．

A 71-year-old female was referred to our hospital for an assessment of dizziness and faintness in April 1995. Electrocardiogram revealed frequent torsade de pointes (Tdp) with QT prolongation (QTc 0.67s) and negative Twave in precordial leads. She had been taking eryth-romycin for two weeks followed by sparfloxacin for two days because of bronchitis. The chest X-ray presented moderate cardiomegaly with a cardiothoratic ratio of 0.68. Echocardiogram showed mild light ventricular hypertrophy and mild mitral regurgitation with an ejec-tion fraction of 70%. Laboratory data showed mild anemia and liver dysfunction, but the renal function and electrolyte concentration were normal. Since drug-induced QT prolongation was suspected, erythromycin and sparfloxacin were discontinued. Tdp could be ter-minated by direct-current cardiovesion and prevented by temporary RV pacing. QTc got gradually shorter and Tdp disappeared at the fifth clay after admission. Both sparfloxacin and erythromycin (per os) have the effect of prolonging the duration of QT interval) Although there had been no report of Tdp induced by either of these drugs in Japan, we judged that sparfloxacin and erythromycin administered orally at the same time had caused QT prolongation and Tdp.