title: Torsades de pointes ventricular tachycardia induced by clarithromycin and disopyramide in the presence of hypokalemia.
abstract: We report a 76-year-old woman who developed TdP ventricular tachycardia induced by combined use of clarithromycin and disopyramide. She had a history of myocardial infarction 5 years earlier and has taken disopyramide for supraventricular arrhythmias. In addition, she had taken clarithromycin for upper respiratory tract infection. On admission, an ECG showed prolongation of QTc interval to 0.71 seconds and self-terminating TdP occurred several times. Disopyramide was metabolized by the cytochrome enzyme CYP3A4 and clarithromycin competitively inhibits this enzyme, probably resulting in an increase in plasma concentration of disopyramide. We should consider this possibility when prescribing clarithromycin in combination with antiarrhythmic agent disopyramide.
authors.affiliation: Department of Cardiology, Jichi Medical School, Tochigi, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashi
authors.forename: U
authors.initials: U
authors.lastname: Ikeda
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Mitsuhashi
authors.forename: K
authors.initials: K
authors.lastname: Shimada
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects* / Q000097:blood / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D001145:Arrhythmias, Cardiac / Q000188:drug therapy; D017291:Clarithromycin / Q000009:adverse effects*; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004206:Disopyramide / Q000009:adverse effects* / Q000097:blood / Q000378:metabolism; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006801:Humans; D007008:Hypokalemia / Q000150:complications* / Q000503:physiopathology; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009203:Myocardial Infarction / Q000150:complications; D012141:Respiratory Tract Infections / Q000188:drug therapy; D016171:Torsades de Pointes / Q000139:chemically induced*
chemical_list: D000889:Anti-Arrhythmia Agents; D000900:Anti-Bacterial Agents; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D004206:Disopyramide; D017291:Clarithromycin