Background: The treatment of painful diabetic polyneuropathy (DPN) is often inadequate and frequently limited by the systemic adverse effects of medications, necessitating the evaluation of novel treatments.
Objective: To evaluate the effectiveness, tolerability, and impact on quality of life of the 5% lidocaine patch in painful diabetic polyneuropathy.
Design: Open-label, flexible-dosing, 3-week study with a 5-week extension.
Setting: Outpatient clinics and clinical research centers.Patients Volunteer sample of 56 patients with clinically defined painful diabetic polyneuropathy of longer than 3 months' duration. Intervention The 5% lidocaine patch, with a maximum of 4 patches daily for 18 hours.
Main outcome measures: Change in mean daily pain diary ratings from baseline to week 3. Secondary end points included assessments of safety, tolerability, and quality of life.
Results: Patients with painful diabetic polyneuropathy showed significant improvements in pain and quality-of-life outcome measures during a 3-week treatment period. These benefits were maintained in a subgroup of patients treated for an additional 5 weeks, during which taper of concomitant analgesic therapy was permitted. Adverse events were minimal, and systemic accumulation of lidocaine did not occur.
Conclusions: Up to four 5% lidocaine patches for up to 18 h/d are well tolerated in patients with painful diabetic polyneuropathy, significantly improve pain and quality-of-life ratings, and may allow tapering of concomitant analgesic therapy. Given the open-label design of this trial, a randomized controlled trial is necessary to confirm these results.