Long-term clinical experience with mexiletine.

Mexiletine was given to 12 patients for different periods of time varying from 4 to 96 months, with a mean of 47.8 months. At the latest follow-up in August 1983, five patients had been taking mexiletine for 74 to 96 months (mean 85 months). Mexiletine was well tolerated and serious side effects were not seen. In particular, there was no rise in antinuclear factor titer. The serum level of mexiletine was easily maintained within the therapeutic range, and most side effects correlated closely with the drug level. It is concluded that mexiletine can be administered for a long time as a safe alternative to other antiarrhythmic drugs.