Mexiletine in treatment of ventricular arrhythmias. A long-term follow-up.

Maxiletine, a new drug effective in the treatment of ventricular arrhythmias, was given to 20 patients for approximately 2 years. The study was designed to investigate the nature and prevalence of side-effects during long-term therapy, and the degree of correlation between such effects and the serum levels of the drug. The methodology used to determine the serum level is described. Mexiletine was well tolerated and serious side-effects were not seen. In particular, antinuclear factor was not detected during the treatment period. The serum level of mexiletine was easily maintained within the therapeutic range, and most side-effects correlated closely with the drug level. Mexiletine appears to be an effective alternative to currently available antiarrhythmic agents.