1 The aim of this study was to evaluate the influence of renal insufficiency on the plasma pharmacokinetics of mexiletine, a new antiarrhythmic agent, in human beings. 2 Mexiletine was administered orally three times daily for 10 days to 15 patients with chronic renal failure (creatinine clearance lower than 30 ml/min) and to 9 subjects with normal renal function. 3 The use of low doses of mexiletine was possible owing to the development of a new fluorescence h.p.l.c. method with a limit of sensitivity lower than 20 gn/ml. 4 Our results clearly indicate that the plasma kinetics of mexiletine are not modified when the renal clearance of creatinine is higher than 10 ml/min.

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