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(Circulation. 1996;94:607-609.)
© 1996 American Heart Association, Inc.

Articles

Of Oocytes and Runny Noses

Michael R. Rosen, MD

the Departments of Pharmacology and Pediatrics, College of Physicians and Surgeons, New York, NY.

Correspondence to Michael R. Rosen, MD, the Department of Pharmacology, College of Physicians and Surgeons, 630 W 168th St, New York, NY 10032.

Key Words: Editorials • arrhythmia • antiarrhythmia agents

	Introduction

 
The paper by Roy et al¹ detailing the effects of the nonsedating antihistamine terfenadine on two K channels in an oocyte system and published in the current issue of Circulation may seem at first blush to deal with esoterica. Yet, a disturbing number of case reports^{2 3} and papers^{4 5 6 7} in the medical literature have documented QT-interval prolongation and torsade de pointes in patients taking terfenadine alone or together with antimycotics such as ketoconazole or antibiotics such as erythromycin. On the basis of such information, any physician considering therapy with nonsedating antihistamines must incorporate awareness of the acquired long-QT syndrome in the decision-making process.

The study by Roy et al¹ is also a reminder that our knowledge concerning acquired long-QT syndrome is advancing with impressive rapidity in ways that impact directly on our understanding of pathophysiology and patient care. Families of drugs including but not limited to antiarrhythmics that prolong repolarization by blocking K⁺ channels or increasing inward Na⁺ currents,⁸ macrolide antibiotics, and pyrrole antimycotics^{3 4 5 6 7} all have the potential to prolong the QT interval and induce arrhythmias and/or death. With respect to the mechanism whereby nonsedating antihistamines prolong the QT interval, the focus of investigation has been the delayed rectifier current, I_K. A major breakthrough here came in the report by Woosley et al⁴ demonstrating terfenadine block of I_K in feline ventricle. Subsequently, terfenadine has been reported to block the transient outward current (I_to1) as well as the ultrarapid (I_Kur), rapid (I_Kr), and slow (I_Ks) components of . . . [Full Text of this Article]

This article has been cited by other articles:

				W Haverkamp, G Breithardt, A.J Camm, M.J Janse, M.R Rosen, C Antzelevitch, D Escande, M Franz, M Malik, A Moss, et al. The potential for QT prolongation and proarrhythmia by non-antiarrhythmic drugs: clinical and regulatory implications. Report on a Policy Conference of the European Society of Cardiology Eur. Heart J., August 1, 2000; 21(15): 1216 - 1231. [PDF]

				W. Haverkamp, G. Breithardt, A.J. Camm, M. J Janse, M. R Rosen, C. Antzelevitch, D. Escande, M. Franz, M. Malik, A. Moss, et al. The potential for QT prolongation and pro-arrhythmia by non-anti-arrhythmic drugs: Clinical and regulatory implications: Report on a Policy Conference of the European Society of Cardiology Cardiovasc Res, August 1, 2000; 47(2): 219 - 233. [Full Text] [PDF]