Torsades de Pointes After Combined Treatment of Terfenadine and Ketoconazole

Park, Sang Joon; Kim, Ki Hyun; Kim, June Soo; Ryu, Jae Choon; Joo, Shin Bae; Gwon, Hyeon Cheol; Park, Seung Woo; Kim, Duk Kyung; Lee, Sang Hoon; Hong, Kyung Pyo; Park, Jeong Euy; Lee, Won Ro

Abstract

Terfenadine is widely used because of nonsedating effect. But It could rarely provoke a potentially lethal ventricular tachyarrhythmia. Recently, we experienced two cases of torsades de pointes(TDP) of occurred after combined use of terfenadine and ketoconazole in usual dose. In one case, 31-yr-old female presented palpitation and recurrent syncope of sudden onset after ingestion of terfenadine 60mg and ketoconzole 200mg 5 times. On attack, ECG showed a polymorphic ventricular tachycardia, and after attack, showed prolongation of QT interval and TU wave changes. Her laboratory findings were not contributory. TDP was controlled with MgSO4 and isoproterenol infusion. Then, QT interval was normalized and no further episode occurred. In the other case, 32-yr-old female presented palpitation and recurrent syncope of sudden onset after ingestion of terfenadine 60mg and ketoconzole 200mg 5 times. ECG showed prolongation of QT interval and TU wave changes. Her laboratory findings were not contributory. TDP was controlled with MgSO4 and isoproterenol infusion. Then, QT interval was normalized and no further episode occurred.