OBJECTIVE-To investigate the efficacy and safety of mexiletine in the
treatment of painful diabetic neuropathy. RESEARCH DESIGN AND METHODS-
A total of 126 insulin-treated diabetes patients with painful diabetic
neuropathy were randomly allocated to three dosages of mexiletine or
placebo. The Visual Analog Scale (VAS) for pain/discomfort was scored
each day during daytime and nighttime, and sleeping disturbances were
also recorded by the patients. Plasma levels of mexiletine and 24-h el
ectrocardiogram (ECG) mapping were assessed before and during the 3-we
ek study period. RESULTS - A significant reduction in sleep disturbanc
es and pain during nighttime was observed in the group of patients tak
ing the highest dosage (675 mg/day) of mexiletine compared with the ot
her groups. No significant correlation was found between plasma concen
tration of mexiletine and the therapeutic effect or adverse events. No
serious adverse events were seen. The 24-h ECG mapping did not disclo
se onset of significant arrhythmias in any patient. CONCLUSIONS - Mexi
letine in a dosage of 675 mg daily can reduce pain caused by diabetic
neuropathy, and the effect of this drug appears to have a rapid onset.