[Clinical study of the antiarrhythmic action of Mexityl in ventricular disorders of the cardiac rhythm].

The anti-arrhythmic activity of mexitil was studied in 36 patients with frequent, prognostically unfavourable ventricular extrasystoles of various etiology. Quantitative and qualitative assessment of rhythm disorders was accomplished by bicycle ergometry and ECG recording for 24 hours by means of portable monitors. The disorders of rhythm were appraised prior to treatment, during mexitil medication in daily doses of 750--1200 mg/24 hrs administered for 3--5 days, and against the background of placebo. The effect of a single 250 to 600 mg dose of mexitil was appraised by monitoring the ECG for three and a half hours. The concentration of mexitil in blood plasma and saliva was tested by gas-fluid chromatography. A positive effect of mexitil treatment manifested in complete correction of ventricular extrasystoles or the reduction of their number by more than half and complete elimination of group extrasystoles and paroxysms of ventricular tachycardia was produced in 66 per cent of patients according to the daily ECG monitoring finds and in 76 per cent of patients according to the results of bicycle ergometry. The antiarrhythmic effect developed 62 minutes, on the average, after oral administration of a single 250--600 mg dose of mexitil and lasted 5--8 hours and more. The therapeutic concentration of mexitil ranged from 0.6 to 0.9 micrograms/ml in blood plasma and from 10.3 to 15.8 micrograms/ml in saliva. In 36 per cent of patients side effects (mainly muscular tremor, lassitude and headache) were noted. It is concluded that mexitil possesses high anti-arrhythmic activity in ventricular extrasystole. To avoid side effects it is recommended to begin treatment in a dose of 250 mg given three times daily, and if necessary gradually increase the single dose to 400 mg and the daily dose to 1200 mg.