In 12 healthy volunteers who received orally 100, 200, 300, 400 and 600 mg mexiletine at weekly intervals, the maximum plasma concentration of mexiletine and AUC increased linearly with the dose of mexiletine. Between doses there were no significant differences in the values for clearance and volume of distribution of mexiletine but there were for plasma elimination half-life. These results indicate that the kinetics of mexiletine are linear.

In a placebo controlled open study in six healthy male volunteers (+)-sotalol in the dose range 0.125 mg kg-1-2.0 mg kg-' intravenously, was found to have little or no ,3-adrenoceptor blocking activity in comparison to the racemic mixture (+)-sotalol. The repolarization effects of (+)-and (+-)-sotalol on the QTc interval however were comparable over the same dose range. The P-adrenoceptor blocking activity and repolarization effects of sotalol appear to be unrelated.