Amiodarone does not affect clearance of mexiletine
Clinical evidence,mechanism, importance and management
The clearance of mexiletine in 10 patients did not differ before and after 1,3 and 5 months concurrent use of amiodarone. In addition, clearance of mexiletine did not differ between these patients and 155 other patients not taking amiodarone (See reference number 1).
Class Ib antiarrhythmics are usually associated with shortening of QT interval, and could therefore be expected to reduce QT prolongation and risk of torsade de pointes seen with amiodarone alone (for examples of this effect of mexiletine see also Mexiletine + Beta blockers interaction,
and Mexiletine + Quinidine interaction. However, note that UK manufacturer of mexiletine(See reference number 4)says that it may exacerbate arrhythmias [as all antiarrhythmics may], but also that it may be used concurrently with amiodarone. The two drugs have been used together successfully (See reference number 5,6).
Yonezawa E,Matsumoto K, Ueno K, Tachibana M, Hashimoto H, Komamura K, Kamakura S, Miyatake K, Tanaka K. Lack of interaction between amiodarone and mexiletine in cardiacarrhythmia patients. J Clin Pharmacol (2002) 42, 342–6.
Tartini R,Kappenberger L, Steinbrunn W. Gefährliche Interaktionen zwischen Amiodaron undAntiarrhythmika der Klasse I. Schweiz Med Wochenschr (1982) 112, 1585–7.
Boehringer Ingelheim. Personal Communication,July 1995.
Mexitil (Mexiletine). Boehringer Ingelheim Ltd. UK Summary of product characteristics,May2003.
Waleffe A,Mary-Rabine L, Legrand V, Demoulin JC, Kulbertus HE. Combined mexiletineand amiodarone treatment of refractory recurrent ventricular tachycardia. Am Heart J (1980) 100, 788–93.
Hoffmann A,Follath F, Burckhardt D. Safe treatment of resistant ventricular arrhythmias witha combination of amiodarone and quinidine or mexiletine. Lancet (1983) i, 704–5.