[Acute myocardial uptake of lidocaine, mexiletine and amiodarone].

To assess acute myocardial uptake of antiarrhythmic drugs, we measured drug concentrations simultaneously in the aorta and in the coronary sinus during diagnostic cardiac catheterization. Measurements were taken 1, 2, 3, 4, 5, 7, and 10 minutes after intravenous bolus application of lidocaine (n = 10, 25 mg), mexiletine (n = 5, 25 mg and n = 10, 100 mg), or amiodarone (n = 10, 25 mg). Drug levels were measured by high-pressure liquid chromatography. Maximal concentrations were observed after 2-5 min. After 3-5 min coronary sinus levels exceeded aorta levels, indicating the end of net myocardial drug uptake. In contrast to lidocaine and amiodarone, no mexiletine was found in the coronary sinus 15 s after the end of drug application, obviously indicating a high myocardial drug content. Furthermore, the data provide an explanation for the acute efficacy of amiodarone. The myocardial uptake may result in various pharmacodynamic effects of antiarrhythmic drugs.