June 23, 2004 — The 5% lidocaine patch significantly reduces pain, improves quality of life (QOL), and may allow tapering of concomitant analgesic therapy in patients with painful diabetic polyneuropathy (DPN), according to an open-label, flexible-dosing study published in the June issue of the Archives of Neurology.
"The treatment of painful DPN is often inadequate and limited by the systemic adverse effects of currently available regimens," write Richard L. Barbano, MD, PhD, and colleagues, from the University of Rochester School of Medicine and Dentistry in New York. "Potential advantages of the 5% lidocaine patch in DPN are its lack of systemic adverse effects and minimal interaction with other medications."
The investigators enrolled 56 patients with a minimum three-month history of painful DPN. Subgroups included patients with allodyna (DPNA, n = 19) and without allodyna (DPNNA, n = 37). Patients were allowed to cover the area of maximal pain with 5% lidocaine patches up to four times daily in an 18-hour span (six hours off) for three weeks. Dose increases in prior stabilized analgesic therapy and new analgesic therapy were not allowed. Patients at one of three participating institutions were treated for an additional five weeks, during which taper of concomitant analgesic therapy was allowed.
At week 3, 70% of patients showed a significant reduction of at least 30% in weekly mean pain diary ratings. Results were similar among patients with and without allodyna.
QOL likewise showed significant improvement as measured by Brief Pain Inventory (BPI) and short-form McGill Pain Questionnaire (SF-MPQ) total and subcategory scores, as well as the Beck Inventory Depression (BID) score and scores on several categories in the Profile of Mood States (POMS). Results were similar between DPNA and DPNNA patients.
Of 28 patients treated for eight weeks, seven underwent tapering of concomitant analgesic therapy. Three patients discontinued the additional pain medication while four maintained the therapy at reduced dosage. The beneficial responses observed at week 3 were maintained at week 8 regardless of whether patients had allodyna.
No serious adverse effects occurred during the trial. Mean plasma lidocaine levels remained stable and well below levels associated with an anti-arrhythmic effect or toxicity throughout the study, indicating that systemic accumulation did not occur. "These results suggest that the generally excellent tolerability of the 5% lidocaine patch might translate to improvements in QOL that may be less likely to occur with more poorly tolerated treatments...and the beneficial response suggests that it may be an effective treatment for the management of painful DPN," the authors note, suggesting that a double-blind, randomized, vehicle-controlled trial is needed to confirm their observations.
Two of the authors received research grants from Endo Pharmaceuticals for conducting this trial, and they disclosed financial relationships with other pharmaceutical companies. One other author also disclosed financial relationships with other pharmaceutical companies.
Arch Neurol. 2004;61:914-918
Reviewed by Gary D. Vogin, MD
Medscape Medical News © 2004 Medscape
Cite this: Yael Waknine. Lidocaine Patch Safe and Effective for Diabetic Neuropathic Pain - Medscape - Jun 23, 2004.