To investigate the efficacy and safety of mexiletine in the treatment of painful diabetic neuropathy.
A total of 216 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 electrocardiogram (ECG) mapping were assessed before and during the 3-week study period.
A significant reduction in sleep disturbances and pain during nighttime was observed in the group of patients taking the highest dosages (675 mg/day) of mexiletine compared with the other groups. No significant correlation was found between plasma concentration of mexiletine and the therapeutic effect or adverse events. No serious adverse events were seen. The 24-h ECG mapping did not disclose onset of significant arrhythmias in any patient.
Mexiletine 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.